Prevalence of smoking-proxy electronic inhaling system ... · 6 Prevalence of smoking-proxy electronic inhaling system (SEIS) use and its association with tobacco initiation in youths:

Prevalence of smoking-proxy electronic inhaling system (SEIS)

use and its association with tobacco initiation in youths:

a systematic review



a systematic review

Sze Lin Yoong1,2,3, Flora Tzelepis1,2,3, John Wiggers1,2,3, Christopher Oldmeadow1,3, Li Kheng Chai1, Christine Paul1,3, Melanie Kingsland1,2,3, Luke Wolfenden1,2,3

1. School of Medicine and Public Health, University of Newcastle, Callaghan, New South Wales 2308, Australia

2. Hunter New England Population Health, Hunter New England Local Health District, Wallsend, New South Wales 2287, Australia

3. Hunter Medical Research Institute, Lot 1, Kookaburra Circuit, New Lambton Heights, New South Wales 2305, Australia

Document prepared for the World Health Organization



a systematic review

This report was prepared at the request of WHO Prevention of Noncommunicable Diseases. The findings, interpretations, and conclusions expressed in this work do not necessarily reflect the views of WHO.

Contents

Acknowledgements 6

Executive summary 7 Background 7 Objectives 7 Methods 7 Results 8 Conclusions 10

1. Background 11

2. Objectives 13

3. Methods 14 3.1 Inclusion criteria 14 3.2 Search strategy 15 3.3 Screening and data extraction 16 3.4 Critical appraisal 16 3.5 Data synthesis 17 3.5.1 Objective 1 17 3.5.2 Objective 2 18

4. Results 19 4.1 Eligible studies and study characteristics 19 4.1.1 Objective 1 19 4.1.2 Objective 2 20 4.2 Risk of bias 34 4.2.1 Objective 1 34 4.2.2 Objective 2 34 4.3 Overall prevalence of SEIS use among young people (objective 1) 34 4.4 Prevalence among non-smokers (objective 1) 36

5 Prevalence of smoking-proxy electronic inhaling system (SEIS) use and its association with tobacco initiation in youths: a systematic review


4.5 Prevalence among current smokers (objective 1) 37 4.6 Exploring heterogeneity (for objective 1) 37 4.7 Objective 2 38

5. Discussion and conclusion 40 5.1 Discussion 40 5.2 Conclusion 42

References 43

Annexes 49



AcknowledgementsThe authors would like to acknowledge Debbie Booth for running the database search and Christophe Lecathelinais and Alessandra Bisquera for statistical support.

Declaration of conflict of interestAll authors declare no conflict of interest.



Executive summary

BackgroundTobacco smoking remains a leading cause of death and disability worldwide. E-cigarettes (referred to here as smoking-proxy electronic inhaling systems, or SEIS) are marketed as having the potential to aid smoking cessation among current smokers, but may also be associated with increased likelihood of initiating tobacco smoking for non-smokers. A number of studies have suggested an increasing trend in SEIS use among youths, particularly among non-tobacco smokers. A positive association between SEIS use and tobacco use has been consistently reported in cross-sectional studies. To better understand the potential impact of SEIS use by young people, a synthesis of evidence regarding the prevalence and trends of SEIS use among this group is required, as is a synthesis of longitudinal data on the association between SEIS and future tobacco cigarette use.

ObjectivesThe objectives of the study are as follows:

1. To describe among young people (aged 10–20 years) the population prevalence and trends in prevalence of smoking-proxy electronic inhaling system (SEIS) use overall and among non-smokers and current smokers by country and by sex.

2. To synthesize findings from longitudinal studies of SEIS use by young people (aged ≤ 20 years) and its association with initiation of tobacco cigarette use.

MethodsA systematic review of the peer-reviewed and grey literature was undertaken in December 2015. Studies were included for objective 1 if they described the prevalence of SEIS use in a general population sample of young people aged ≤ 20 years in a defined geographical region using census or probability sampling. Studies where participants were recruited based on a specific health condition or as members of particular socioeconomic groups were excluded. There were no restrictions regarding the location of study, peer review status or language. A sensitivity analysis was undertaken including studies that did not include probability sampling but sampled for representativeness.



For objective 2, studies were included if they used a prospective longitudinal cohort design and assessed the association between SEIS use in young people aged ≤ 20 years at baseline and later use of combustible tobacco products. There were no restrictions on study sampling or recruitment methods, location of the study, peer review status or language of publication.

A single-search strategy for both objectives was employed that encompassed electronic databases of peer-reviewed manuscripts, grey literature Google searches, hand searches of relevant reference lists and consultation with experts in the field. Screening and data extraction were undertaken by three reviewers for peer-reviewed research and one reviewer for grey literature.

For both objectives, data from included studies were combined using random effect meta-analyses. To provide estimates of the prevalence of SEIS use in the previous three years, pooled estimates of “ever use” or “use in last 30 days (‘current use’)” of SEIS are also reported from studies using data collected between 2013 and 2015. To describe trends in prevalence of SEIS use, changes in prevalence of “ever use” or “use in last 30 days” over time for all studies between 2008 and 2015 were pooled, and described narratively by country where multiple comparable prevalence estimates were available during this time. All analyses were repeated for both current and non-current cigarette smokers. This analysis was repeated in a sensitivity analysis including four additional studies that did not use probability sampling but had sampled to be representative of the population.

Results Included studiesObjective 1. Overall, 2281 abstracts were screened (2246 electronic databases, 19 reports from the Google search and 16 reports from expert contacts). From these, 135 full texts were obtained for full-text screening, of which 28 publications reporting findings from 35 studies (each study represents a single survey) were included. An additional four publications reporting on findings from six studies were included in the sensitivity analysis. All studies utilized self-reported questionnaires to assess SEIS use. Eight of 32 studies satisfied seven of 10 quality assessment criteria, 17 satisfied five or six criteria, and seven satisfied three or four criteria. None of the studies reported on the reliability of the measures employed.

Objective 2. Overall, 2281 articles were screened and 119 full texts were obtained for further screening, with three studies being included in the final meta-analysis. All studies were undertaken in the United States of America. None of the studies were classified as having a sample representative of the target population and one study had a small sample of SEIS users at baseline (n=16). For all studies it was unclear whether the self-reported methods for collecting data on SEIS use and subgroup characteristics were reliable.



Overall prevalence of SEIS use among overall sample(a) Ever use. The pooled estimate of the prevalence of SEIS ever use from 20 studies conducted between 2013 and 2015 was 16.4% (95% CI: 12.5–20.6%). Prevalence of ever use was 17.4% (95% CI: 10.9–25%) among males (from 14 studies) and 14.3% (95% CI: 8.7–21%) among females (from 14 studies). In the sensitivity analyses (23 studies), the prevalence of ever use was 16.1% (95% CI: 12.6–20.0%) overall, 19.3% (95% CI: 12.5–27.1%) among males and 15.5% (95% CI: 9.9–22.2%) in females (13 studies).

With one exception (Italy), for all five countries where multiple comparable prevalence estimates were available between 2008 and 2015, the prevalence of ever use increased over time (New Zealand, Poland, Republic of Korea, United States).

(b) Current use. The pooled estimate of the prevalence of current SEIS use from 19 studies conducted between 2013 and 2015 was 5.6% (95% CI: 3.4–8.3%). The prevalence of current use was 6.3% (95% CI: 3.7–9.6%) among males and 4.3% (95% CI: 2.4–6.8%) in females (12 studies). In the sensitivity analyses with an additional five studies (24 studies), the prevalence of SEIS ever use was 5.5% (95% CI: 3.5–7.9%) overall, 7.4 % (95% CI: 4.5–10.8%) among males and 4.9% (95% CI: 2.8–7.4%) in females (13 studies).

In three of the five countries where multiple comparable estimates of prevalence were available between 2008 and 2015, prevalence of current use increased (Poland, United Kingdom, United States). The prevalence of current SEIS use decreased in Hungary between 2012 and 2013, while the prevalence remained stable in Italy.

Prevalence among non-smokers(a) Ever use. The pooled estimate of the prevalence of ever use among non-smokers from 13 studies conducted between 2013 and 2015 was 7.0% (95% CI: 5.1–9.3%). In the sensitivity analyses with an additional three studies, the prevalence of SEIS ever use was 6.4% (95% CI: 4.6–8.5%) among non-smokers.

Multiple estimates of prevalence over time in the United States indicated that ever use by non-smokers increased. In contrast, the prevalence of such use did not change in Italy.

(b) Current use. The pooled estimate of the prevalence of current SEIS use among non-smokers from nine studies conducted between 2013 and 2015 was 1.5% (95% CI: 0.3–3.5%). In the sensitivity analyses with an additional four studies (15 studies), the prevalence of SEIS ever use among non-smokers was 1.3% (95% CI: 0.4–2.8%).

Comparable estimates of prevalence of current use by non-smokers over time were available between 2008 and 2015 from three countries: Italy, Poland and the United States. In the United States, the prevalence of current use in non-smokers increased in both middle school- and high school-aged students between 2011 and 2014. In Poland, the prevalence of use increased, while in Italy prevalence was 0% across all periods of data collection.



Prevalence among current smokers(a) Ever use. The pooled estimate of the prevalence of SEIS ever use among current tobacco smokers from 13 studies conducted between 2013 and 2015 was 54.7% (95% CI: 45.9–60.5%). In the sensitivity analyses with an additional two studies (15 studies), the prevalence of SEIS ever use was 53.2% (95% CI: 45.9 –60.5%) among current smokers.

In the United States, the prevalence of SEIS ever use among current tobacco smokers increased, while it remained stable in Italy.

(b) Current use. The pooled estimate of the prevalence of SEIS current use among current tobacco smokers from 10 studies conducted between 2013 and 2015 was 19.4% (95% CI: 8.3–33.5%). In the sensitivity analyses with an additional two studies (14 studies), the prevalence of SEIS ever use was 17.8% (95% CI: 8.8–28.9%).

Multiple comparable estimates of prevalence of SEIS use across 2008–2015 in Poland and the United States showed an increase in current use of SEIS among smokers. In Italy, prevalence remained stable.

Association between SEIS ever use and tobacco cigarette use Three studies conducted in the United States were included in the analysis, with each study indicating that non-tobacco-smoking young people who were SEIS users were significantly more likely to be tobacco smokers at follow-up. Pooled analysis of the studies indicated that SEIS smokers at baseline had an increased adjusted odds ratio (AOR 2.19; 95% CI: 1.46–3.3%; I2 = 59.7%) of being a tobacco cigarette user at follow-up.

ConclusionsThis systematic review and meta-analysis found substantial differences in prevalence and changes in prevalence of SEIS use by country. More than half of all young tobacco smokers in Canada, Ireland, New Zealand, the United Kingdom and the United States had ever used SEIS. Use of SEIS among young people was reportedly increasing in Poland and the United States but not in some other countries, for example Hungary and Italy. Pooled findings from two longitudinal studies indicated that the use of SEIS by non-smokers more than doubled the odds of tobacco smoking at follow-up.

Despite current low prevalence of SEIS use among non-smoking young people in most jurisdictions, the finding of a longitudinal association between SEIS use and subsequent tobacco use, and the increasing prevalence of SEIS use among non-smoking young people in some countries, supports the need for strategies to discourage SEIS uptake among non-smokers.



1. Background

Internationally, tobacco use is the leading cause of preventable death and disability (1). The 2013 Global Burden of Disease Study reported that tobacco use accounted for 6.1 million deaths and 143.5 million disability-adjusted life-years globally (2). While there is considerable between-country variation in the current prevalence of tobacco use, the global prevalence declined between 1980 and 2012 from 41.2% to 31.1% for men and 10.6% to 6.2% for women (3). Globally, the largest annualized rate of change over this period occurred among those aged 15–19 years, where the rate declined by 1.8% each year (3). Given the significant health and societal burden of tobacco use (2), comprehensive strategies to prevent initiation and assist cessation have been recommended (4).

There has been considerable debate about the potential role of e-cigarettes in addressing tobacco use, particularly among young people (5, 6). Electronic cigarettes (referred to here as smoking-proxy electronic inhaling systems, or SEIS) are battery-operated devices designed to deliver a solution as an aerosol (or “vapour”) typically made up of propylene glycol or glycerol (glycerine), nicotine, and flavouring agents, which is inhaled by users (7). The devices are designed to simulate the act of smoking tobacco cigarettes to allow the consumption of nicotine without the burning of tobacco. SEIS has been primarily marketed as an alternative to combustible tobacco, as an aid to reduce or cease tobacco smoking or a means of using nicotine in smoke-free environments (7). To date, the impact of SEIS in aiding smoking cessation is equivocal, with a recent Cochrane review reporting a small positive effect from only two randomized controlled trials (8). Concerns regarding the long-term safety of the use of SEIS however have led to at least 55 countries introducing legislation or bans prohibiting or restricting the sale of SEIS (9).

Since their introduction, the use of SEIS among young people has received considerable attention. A 2014 systematic review reported increasing use of SEIS among young people in countries such as Poland and the United States since 2011 (10). Findings from the review highlighted some differences in patterns of SEIS use among young people compared to older individuals, with a significantly greater proportion of adolescent



SEIS ever users reporting no previous use of tobacco cigarettes. Similarly, a national study in Poland reported that over 20% of adolescent SEIS users were non-tobacco smokers (11); and in some United States jurisdictions, SEIS use among adolescents exceeded traditional tobacco cigarette use (12). While a small proportion of young adults report using SEIS to aid cessation (13, 14), studies suggest that younger adults are more likely to use SEIS primarily for experimentation purposes (10, 13).

The increasing rate of SEIS use among young people generally and among non-smokers in particular has led to concerns that SEIS use and particularly experimentation by young people could lead to nicotine dependence into adulthood and subsequent tobacco initiation (15). The potential mechanisms driving this process are unknown, though a recent review proposed a number of hypothesized pathways that may account for the initial uptake of SEIS and the transition between SEIS experimentation and nicotine dependence (16). To date, however, such concerns that SEIS use may lead to tobacco uptake have primarily been examined via cross-sectional studies. These studies reported positive associations between SEIS use and tobacco smoking behaviour among youths who had not previously used tobacco (17–19). In the absence of longitudinal studies, such findings do not allow for the examination of causality and directionality (i.e. whether SEIS use leads to initiation of tobacco smoking).

A synthesis of the current prevalence and patterns of SEIS use among young smokers and non-smokers is needed to better understand the potential impacts of SEIS use on adolescent tobacco smoking behaviour. Further, a synthesis of longitudinal data regarding the association between SEIS and tobacco smoking by young people is needed to allow examination of the potential impact of SEIS use on subsequent tobacco smoking and other forms of combustible tobacco use. For the purpose of this systematic review, “young people” have been defined as those aged 10–20 years and “adolescents” have been defined as those aged 15–19 years, consistent with WHO definitions.



2. Objectives

The objectives of the study are as follows:

1. To describe among young people (aged ≤ 20 years) the population prevalence and trends in prevalence of smoking-proxy electronic inhaling system (SEIS) use overall and among non-smokers and current smokers by country, sex and SEIS type.

2. To synthesize findings from longitudinal studies of SEIS use by young people (aged ≤ 20 years) and initiation of tobacco cigarette use.



3. Methods

A systematic review of the peer-reviewed and grey literature was undertaken between August and December 2015. The review was conducted in accordance with the Cochrane Collaboration review methods and involved searching multiple electronic databases, using two independent reviewers, undertaking formal critical appraisal with the Joanna Briggs Institute critical appraisal checklist for studies reporting prevalence data (20), and undertaking meta-analysis where appropriate.

3.1 Inclusion criteria Objective 1. For this objective, studies were included if they described the prevalence of SEIS use in the general population within a defined geographical region (such as province, state or country). To be eligible studies needed to employ census or probability sampling methods, and report SEIS use in young people with a mean age of between 10 and 20 years. For studies that included those aged over 20 years, the study was included if a subgroup analysis of SEIS use among those aged ≤ 20 years was reported. Studies reporting any measure of SEIS (e.g. self-reported, secondary (or proxy) reported or biochemical assessments) were included.

Studies using data from specialist panels (such as online research panels) or cohort studies that did not employ probability sampling procedures and recruitment procedures were excluded, regardless of whether population weights were applied to estimates of SEIS use. Probability sampling has been identified as an important requirement of quality prevalence studies (21). Studies where participants were recruited based on a pre-existing disease or condition (e.g. mental health, hospital), or on the basis of specific socioeconomic characteristics (e.g. located in a lower socioeconomic region) and disease characteristics (e.g. patients with cardiovascular disease), were also excluded. Finally, non-databased publications that did not present new data (e.g. commentaries and opinion pieces) were excluded. There were no other restrictions regarding the location of the study, peer review status or language of publication.



Objective 2. For this objective, studies employing prospective longitudinal cohort designs that aimed to assess the association of SEIS use in young people and initiation of combustible tobacco products were included. Cross-sectional, case control and retrospective studies were excluded as they did not allow direct examination of causality, as were non-databased publications that did not present new data. To be eligible, longitudinal cohort studies needed to include non-smokers with a mean age of between 10 and 20 years at baseline and examine tobacco use at follow-up. Studies reporting any measure of SEIS use (e.g. self-reported, secondary (or proxy) reported or biochemical assessments) and that examined tobacco smoking use at follow-up were included. There were no other restrictions on study sampling or recruitment methods, location of the study, peer review status or the language of publication. No restrictions on sampling methods were employed for this objective as the primary aim was to assess association between baseline SEIS use and tobacco cigarette uptake.

3.2 Search strategyA single-search strategy was employed to identify relevant peer-reviewed and grey literature for both objectives. The search encompassed electronic databases of peer-reviewed manuscripts, Google searches, hand searches and consultation with experts in the field.

• Electronic databases. A systematic search of the electronic databases MEDLINE, EMBASE, PsycInfo, Cochrane and CINAHL was undertaken by an experienced academic librarian. Search terms for SEIS were based on those used in previous systematic reviews of SEIS use (8, 22). Broadly, the search terms included e-cig*, electronic nicotine*, electronic hookah* and e-hookah* as Medical Subject Headings (MeSH) terms. The full search string for each electronic database is provided in Annex 1.

• Google search. Searches were undertaken to identify potentially eligible reports, papers and conference abstracts for inclusion. The terms “electronic cigarette” and “ecigarette” were entered into separate Google.com searches. The results listed on the first 75 pages (750 hits) of each search were examined for relevant grey literature.

• Hand searches. Relevant references examining SEIS use in young people identified in the searches above were examined for potentially eligible studies for inclusion. The reference lists of all eligible studies were also screened for any additional studies potentially relevant to the objectives of this review.

• Experts in the field. Additional information about SEIS use in young people was sought from experts recommended by the Tobacco Unit of the World Health Organization and from selected authors who had published two or more relevant studies in the SEIS field. Experts were asked to identify any published or unpublished manuscripts (e.g. reports, papers, conference abstracts) or additional data relevant

Google.com



to the report objectives. An email was sent to 15 experts on 31 August 2015. One respondent suggested an additional two experts be contacted and an email was sent to these experts on 11 September 2015. One respondent also contacted a further 13 experts on 13 September 2015. Given the rapid progress in the SEIS field, this process was repeated by sending another email to these experts on the 16 December 2015 asking whether they had any recent unpublished data that was relevant to this review. The experts were located in Australia, Canada, Germany, Italy, Romania, the United Kingdom and the United States.

3.3 Screening and data extractionEndNote version X6.0.1 software (Thomson Reuters, PA, United States) was used to manage study inclusion and filter duplicate studies. SLY and LW1 screened all databased results and FT screened all citations from the grey literature search. The full texts of all potentially eligible studies were obtained and study eligibility was determined based on assessment of the full text. Where eligibility was unclear, authors were contacted to request additional information. “Google translate” was used to assist with assessing the eligibility of non-English language manuscripts (n=25), which were all excluded prior to the full-text screening.

SLY, LW or LKC extracted the following information for all included studies in objective 1: author name, publication year, country of study, sample size, participant age range and sex, year of data collection, data collection modality, sampling procedures, measure of SEIS use, type of SEIS used (e.g. e-hookah), prevalence of SEIS use by sex, and prevalence of SEIS use among smokers and non-smokers (including n, percentages and 95% confidence intervals, where available) (see Annex 2). A consensus process was used to resolve any differences in extraction. Data for total denominators were also obtained from other sources (e.g. other references or raw datasets) to allow for inclusion in the meta-analysis. For objective 2, author last name, year of publication, participant characteristics (mean age), study design, country, sampling frame, outcomes, data collection modality, analyses, odds ratio and 95% CI, covariates adjusted for and follow-up time points were extracted by SLY. For the included studies, other supporting publications or reports (for example protocols, full descriptions of study methods from government websites) were also sought to obtain relevant information where the data from the primary study were absent or unclear. Data extraction was undertaken using prepiloted data extraction forms developed for the purpose of the study.

3.4 Critical appraisalTwo reviewers (MK and FT) independently undertook critical appraisal using the Joanna Briggs Institute critical appraisal checklist for studies reporting prevalence data (20). The instrument contains 10 items examining the following study characteristics: sample representativeness, sampling methods, adequacy of sample size, participant and setting descriptions, coverage of sample, objectivity of criteria, reliability of measurement,

1 Authors’ initials: see list of authors.



appropriateness of statistical analysis, confounding factors identified and accounted for, and objective classification of subpopulations (Yes; No; Unclear; and N/A). This tool has been found to have face validity and to be acceptable and easy to use (23).

For objective 2, in addition to completing the Joanna Briggs Institute critical appraisal checklist for studies reporting prevalence data assessment (20), the reviewers also examined the following study characteristics for the longitudinal studies: whether the outcome of interest (tobacco smoking) was absent at baseline, whether known confounders were adjusted for in the analysis, and whether there was appropriate treatment of missing data. For both objectives, where discrepancies in coding emerged between reviewers, inconsistent ratings were discussed between the reviewers until consensus was reached.

3.5 Data synthesisAll analyses were undertaken using Stata version 14 software (StataCorp, College Station, TX, United States) and the Metaprop and Metareg packages. For both objectives, main findings from the individual studies were also described narratively where relevant.

3.5.1 Objective 1Data from included studies were combined using a random effect meta-analysis, weighted according to the inverse variance method. The Freeman-Tukey double arcsine transformation of prevalences was also used to allow for studies with prevalences that were close to zero. Exact 95% confidence intervals for the individual studies were computed.

Pooled estimates of SEIS ever use, and use in last 30 days (“current use”), were reported as stratified by country and sex (where available). Studies that included occasional users were pooled with ever users; and studies that reported regular use were pooled with last 30 days (or current use). Pooled estimates of ever and current SEIS use among non-smokers and smokers were also reported as stratified by country. Estimates of non-smokers included those not currently smoking (including ex-smokers) where available, and estimates of smokers included those reporting using any tobacco (including experimenters and occasional or current users) where available. Where prevalence of SEIS use by current smokers and non-smokers was not specifically reported, estimates of use were calculated using the following information provided in the original publications: number in total sample, prevalence of SEIS users, prevalence of smokers, and prevalence of concurrent SEIS and tobacco users. Estimates of regular/occasional use were available for four studies (24–27). Where individual studies provided weighted and unweighted measures of SEIS prevalence, weighted estimates were used. Pooled estimates of prevalence are reported as an absolute percentage with 95% confidence intervals. Heterogeneity was assessed using the I-squared statistic and reported for each point estimate, together with the chi-square statistic from the likelihood ratio test comparing the random and fixed effects model, the estimated between-study variance and its test of significance. For pooled estimates of current or ever use, this analysis



was repeated in a sensitivity analysis, including studies that did not use probability sampling but attempted to sample in a way that was representative of the population.

To explore additional potential causes of heterogeneity, an exploratory meta-regression was performed with prevalence of ever and current SEIS use among young people overall and by smokers and non-smokers. Covariates included in this analysis included year of data collection, age, sex and country policies regarding the availability and marketing of SEIS to adolescents (classed as consumer product (no regulation), minimum age of purchase overall or banned overall), and MPOWER scores for 2014. Classification for SEIS regulation was made based on a previously published review examining SEIS policy internationally (9). MPOWER scores (out of 100) for countries included in the review were provided by a representative from the World Health Organization. MPOWER scores were introduced following the WHO Framework Convention on Tobacco Control, and are calculated based on six measures that are considered central to tobacco control policies: taxes and pricing; advertising, promotion and sponsorship; protection against second-hand smoke; public warnings against the dangers of tobacco smoking; providing cessation support to those intending to quit; and monitoring policies (1). The multivariable model that explained the most between-study variance was reported.

3.5.2 Objective 2To assess whether use of SEIS at baseline was associated with cigarette use at follow-up, a random effects meta-analysis was undertaken with adjusted log odds ratios. The pooled estimates of the odds ratio with 95% confidence intervals were reported.



4. Results

4.1 Eligible studies and study characteristics 4.1.1 Objective 1Overall, 2281 abstracts were obtained and screened (2246 electronic databases; 19 reports from the Google search and 16 reports from expert contacts). From these, 135 full texts where eligibility was unclear were obtained for full-text screening. Of these, 28 publications that reported findings from 35 studies (each study represents a single survey) were included in the final meta-analyses for at least one of the outcomes. Of those included in the full-text screening, studies were excluded because they examined SEIS use only in individuals aged > 20 (n=55), did not report on prevalence of SEIS use (n=4), did not use probability sampling (n=4), did not sample to be representative of the region (n=14), were not empirical studies (n=12), or included findings previously reported in other published papers (n=18) (Figure A4.1)2. The four studies that described population prevalence but did not use probability sampling were included as part of a sensitivity analysis.

The included publications were conducted in 11 high-income countries: the United States (national and subnational) (n=11) (12, 19, 28–36), Republic of Korea (n=2) (37, 38), New Zealand (n=2) (26, 39), United Kingdom (Scotland and Wales) (n=2) (27, 40), Poland (n=2) (11, 41), Hungary (n=1) (42), Canada (n=2) (43, 44), Hong Kong Special Administrative Region (n=1) (17), France (n=1) (45), Ireland (n=1) (24), Italy (n=1) (25), Iceland (n=1) (46) and Greece (n=1) (47). These studies were conducted between 2008 (37) and 2015 (25), and sample size ranged from 99 (39) to 75 643 (38). Two studies included both young people and adults as part of their sample but presented findings separately for young people (n=99 and n=160–163) (25, 26). All studies reported estimates for young people under 20. All studies utilized self-reported questionnaires completed by participants administered via paper and pencil (n=23) (11, 12, 17, 19, 24, 27–33, 36, 37, 39–42, 44–47), web (n=2) (38, 48), telephone (n=1) (43) or face to face (n=2) (25, 26). Studies either assessed ever use of SEIS (n=23) (11, 24–31, 33, 35–41,

2 Note: all figures are contained within Annex 4.



43–48) or use in past 30 days (“current use”) (n=21) (11, 12, 17, 24–33, 35, 36, 38, 40–43, 47). Four publications also reported regular or occasional use (see Annex 3 for measures) (24–27). Dutra and Glantz (19) reported on the same dataset as Corey et al. (31) (United States National Youth Tobacco Survey 2012 and 2013), but presented findings by smokers and non-smokers. Overall prevalence was included in the meta-analysis only once for these studies. None of the studies examined types of SEIS used. Seventeen publications (reporting on 22 studies) (11, 17, 19, 24, 25, 27, 30, 33, 37–42, 46, 47) reported prevalence of SEIS use by current smokers and non-smokers, but none provided these estimates by sex. An additional four studies conducted in Switzerland (49) and the United Kingdom (50–52) were included in the sensitivity analyses. Study characteristics are reported in Table 1.

4.1.2 Objective 2For objective 2, 2281 articles were screened and 119 full texts were obtained for further screening, with three studies meeting the eligibility criteria and included in the review (Figure A4.2) (54–56). Studies included in the full-text screening were excluded primarily because they were cross-sectional studies, commentaries or reviews (n=79). Other reasons for exclusion included not examining SEIS use (n=5), conducted with adults (n=5), conference abstract of published data (n=1), and did not examine association with tobacco/cigarette smoking (n=26) (Figure A4.2). All included studies were undertaken in the United States and quantified participants’ SEIS ever use via a single question. The mean age for two studies was 14 years and the other was 20 years. Study characteristics are reported in Table 2.



Tabl

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Year

of

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Surv

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scientifically selected

F: 5

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1.1%

M: 48.9%

grad

es

9–12

Que

stio

nnai

re,

pen

and

pape

r

Arrazola, 201

4 (2

9)

Uni

ted

Stat

es20

13N

atio

nal Y

outh

To

bacc

o Su

rvey

(N

YTS)

18 406

; 18

7 sc

hool

s (74.8%

)

A th

ree-

stag

e cl

uste

r sa

mpl

ing

proc

edur

e to

gen

erat

e a

cros

s-se

ctio

nal,

natio

nally

re

pres

enta

tive

sam

ple

of

stud

ents

in g

rade

s 6–

12

from

all

stat

es a

nd th

e D

istr

ict o

f Col

umbi

a. A

stratifi

ed cluster sam

ple,

desi

gned

to o

vers

ampl

e no

n-H

ispa

nic

blac

k an

d H

ispa

nic

stud

ents

, was

em

ploy

ed

F: 49%

M: 5

1%

11–14

ye

ars

(mid

dle

scho

ols)

, 15

–18

ye

ars

(hig

h sc

hool

s)

Que

stio

nnai

re,

pen

and

pape

r



Firs

t aut

hor’s

last

na

me,

yea

rCo

untr

y of

dat

a co

llect

ion

Year

of

data

co

llect

ion

Surv

ey n

ame

nSa

mpl

ing

fram

eSe

x (%

)Ag

e ra

nge

Dat

a co

llect

ion

mod

ality

Arra

zola

, 201

5 (1

2)

Uni

ted

Stat

es20

14N

atio

nal Y

outh

To

bacc

o Su

rvey

(N

YTS)

10 419

m

iddl

e sc

hool

st

uden

ts,

11 459

hi

gh

scho

ol

stud

ents

See Arrazola 201

4 N

ot

repo

rted

11–14

ye

ars

(mid

dle

scho

ols)

, 15

–18

ye

ars

(hig

h sc

hool

s)

Que

stio

nnai

re,

pen

and

pape

r

Babi

neau

, 201

5 (2

4)

Irel

and

2014

2014

You

th

Perc

eptio

n of

Pl

ain

Pack

agin

g St

udy,

a na

tiona

lly

repr

esen

tativ

e sc

hool

-bas

ed

survey of 1

6–17

-ye

ar o

lds

821

A re

pres

enta

tive

sam

ple

of s

econ

dary

sch

ools

from

ar

ound

the

coun

try

was

se

lect

ed fo

r par

ticip

atio

n an

d stratifi

ed based

on

loca

tion,

sch

ool t

ype

and

size

F: 5

0.2%

M: 49.8%

16–17

ye

ars

Que

stio

nnai

re,

pen

and

pape

r

Barn

ett,

2015

(30)

U

nite

d St

ates

(F

lorid

a)

2013

2013

Flo

rida

Yout

h To

bacc

o Su

rvey

12 615

st

uden

ts

from

172

sc

hool

s

The

FYTS

use

d a

two-

stag

e cl

uste

r pro

babi

lity

sam

ple

desi

gn to

obt

ain

a ra

ndom

sam

ple

of p

ublic

m

iddl

e an

d hi

gh s

choo

ls

F: 49%

M: 5

1%

grad

es

6–12

Que

stio

nnai

re,

pen

and

pape

r

Cho,

201

1 (3

7)

Repu

blic

of

Kore

a20

0820

08 Health

Prom

otio

n Fu

nd P

roje

ct in

Re

publ

ic o

f Kor

ea

4 34

1A

clus

ter p

roba

bilit

y sa

mpl

e de

sign

was

use

d.

To d

istr

ibut

e th

e di

stric

ts

even

ly, five schoo

ls were

chos

en b

ased

on

thei

r ge

ogra

phic

al lo

catio

ns

F: 5

1.2%

M: 48.8%

13–

19

year

sQ

uest

ionn

aire

, pe

n an

d pa

per



Firs

t aut

hor’s

last

na

me,

yea

rCo

untr

y of

dat

a co

llect

ion

Year

of

data

co

llect

ion

Surv

ey n

ame

nSa

mpl

ing

fram

eSe

x (%

)Ag

e ra

nge

Dat

a co

llect

ion

mod

ality

Corey, 20

14 (3

1)

Uni

ted

Stat

es20

11, 2

012

Nat

iona

l You

th

Toba

cco

Surv

ey

(NYT

S)

18 866

(2

011)

,a 24

658

(2

012)

see Arrazola 201

4(2

011)

F: 49.4%

M: 5

0.6%

(201

2)

F: 48.9%

M: 5

1.1%

11–14

ye

ars

(mid

dle

scho

ols)

, 15

–18

ye

ars

(hig

h sc

hool

s)

Que

stio

nnai

re,

pen

and

pape

r

Dau

tzen

berg

, 20

13 (4

5)

Fran

ce

(Par

is)

2012

Annu

al s

urve

y co

nduc

ted

by

Paris

San

Tab

ac

2 51

9Su

rvey

was

con

duct

ed o

n 2%

of s

tude

nts

rand

omly

se

lect

ed b

y cl

ass

and

prov

ided

a re

pres

enta

tive

sample of th

e 18

8 00

0 sc

hool

chi

ldre

n of

Par

is

F: 49.5%

M: 5

0.5%

12–

19

year

sQ

uest

ionn

aire

, pe

n an

d pa

per

Dutra, 201

4 (1

9)

Uni

ted

Stat

es20

11, 2

012

Nat

iona

l You

th

Toba

cco

Surv

ey

(NYT

S)

17 353

(2

011)

, 22

529

(2

012)

See Arrazola 201

4F: 49.4%

M: 5

0.6%

Grad

es

6–12

Que

stio

nnai

re,

pen

and

pape

r



Firs

t aut

hor’s

last

na

me,

yea

rCo

untr

y of

dat

a co

llect

ion

Year

of

data

co

llect

ion

Surv

ey n

ame

nSa

mpl

ing

fram

eSe

x (%

)Ag

e ra

nge

Dat

a co

llect

ion

mod

ality

East

woo

d, 2

015

(50)

U

nite

d Ki

ngdo

m

(Eng

land

)

2013

, 201

4Yo

uGov

20

13/201

42 17

7 (2

013)

, 2 06

8 (201

4)

Individu

als ag

ed 16–

18

wer

e sa

mpl

ed d

irect

ly

from

You

Gov’s

onl

ine

pane

l of p

eopl

e w

ho h

ad

prov

ided

con

sent

to b

e co

ntac

ted

and

wer

e se

nt

an e

mai

l inv

itatio

n to

take

pa

rt. I

ndiv

idua

ls a

ged

11–

15 w

ere

recr

uite

d vi

a an

em

ail t

o pa

rent

s or

lega

l gu

ardi

ans

from

the

YouG

ov

pane

l, w

hich

ask

ed th

em

to re

ad th

e in

form

atio

n ab

out t

he s

urve

y, an

d th

en

pass

the

surv

ey o

ver t

o th

eir c

hild

if th

ey a

nd th

eir

child

agr

eed

to ta

ke p

art.

Thos

e gi

ving

con

sent

wer

e as

ked

to fo

llow

a li

nk to

th

e su

rvey

onl

ine

(201

3)

F: 5

2.3%

M: 47.7%

(201

4)

F: 5

1.1%

M: 48.9%

11–18

ye

ars

Web

-bas

ed

ques

tionn

aire

Ford

, 201

6 (5

2)

Uni

ted

King

dom

2014

Yout

h To

bacc

o Po

licy

Surv

ey

(YTP

S)

1 20

5U

sing

rand

om lo

catio

n qu

ota

sam

plin

g,

part

icip

ants

wer

e dr

awn

from

92

elec

tora

l w

ards

acr

oss

the

Uni

ted

King

dom, stratified

by

Governmen

t Office Reg

ion

and A Classification

Of R

esid

entia

l N

eigh

bour

hood

s (A

CORN

)b

F: 5

0%

M: 5

0%

11–

16

year

sFa

ce to

face



Firs

t aut

hor’s

last

na

me,

yea

rCo

untr

y of

dat

a co

llect

ion

Year

of

data

co

llect

ion

Surv

ey n

ame

nSa

mpl

ing

fram

eSe

x (%

)Ag

e ra

nge

Dat

a co

llect

ion

mod

ality

Fotio

u, 2

015

(47)

Gr

eece

2014

2014

Health

Beha

viou

r in

Scho

ol-a

ged

Child

ren

Surv

ey

1 32

0A

natio

nwid

e pr

obab

ility

sa

mpl

e of

stu

dent

s. Sa

mpl

ing

units

wer

e sc

hool

cla

sses

dra

wn

by m

ultis

tage

clu

ster

ed

prob

abili

ty s

ampl

ing

from

th

e M

inis

try

of E

duca

tion’

s co

mpl

ete

listin

g. S

ampl

ing

was

pro

port

iona

l acr

oss

scho

ol ty

pes

and

regi

ons

F: 51.7%

M: 48.3%

15 y

ears

Que

stio

nnai

re,

pen

and

pape

r

Gallu

s, 20

13 (2

5)

Ital

y20

13, 201

4,

2015

Unspe

cifie

dc16

3 (2

013)

, 15

3 (201

4),

160

(201

5)

An overall sample of 3 000

individu

als ag

ed ≥ 15

year

s re

pres

enta

tive

of th

e ge

nera

l Ita

lian

popu

latio

n ag

ed 1

5 ye

ars

and

over

w

as s

urve

yed

(201

3,

2014

)

F: 46%

M: 54%

(201

5)

F: 48%

M: 5

2%

15–

19

year

sc

Face

to fa

ce

Goni

ewic

z, 20

12

(41)

Po

land

2010

–20

11Unspe

cifie

d 13

787

from

144

sc

hool

s an

d 32

un

iver

sitie

s

A three-stag

e stratifi

ed

clus

ter s

ampl

ing

proc

edur

e, w

here

by

scho

ols

and

univ

ersi

ties

wer

e tr

eate

d as

the

prim

ary

unit,

was

use

d.

Regi

ons

with

a p

opul

atio

n of ≤ 20 00

0 were exclud

ed

F: 54.8%

M: 45.2%

15–

19

year

sQ

uest

ionn

aire

, pe

n an

d pa

per

Goniew

icz, 20

14

(11)

Po

land

2013

–20

14Unspe

cifie

d 1 97

0 Se

e Go

niew

icz, 20

12; o

nly

stud

ents

recr

uite

d fr

om 2

1 sc

hool

s ac

ross

two

regi

ons

in P

olan

d w

ere

incl

uded

in

the 20

14 com

paris

on

Not

re

port

ed15

–19

ye

ars

Que

stio

nnai

re,

pen

and

pape

r



Firs

t aut

hor’s

last

na

me,

yea

rCo

untr

y of

dat

a co

llect

ion

Year

of

data

co

llect

ion

Surv

ey n

ame

nSa

mpl

ing

fram

eSe

x (%

)Ag

e ra

nge

Dat

a co

llect

ion

mod

ality

Ham

ilton

, 201

5 (4

4)

Cana

da

(Ont

ario

)20

1320

13 O

ntar

io

Stud

ent D

rug

Use

an

d H

ealt

h Su

rvey

2 83

2Stratifi

ed tw

o-stag

e (s

choo

l, cl

ass)

, tw

o cl

uste

r de

sign

, stude

nts from

42

boards, 198

schoo

ls and

67

1 classroo

ms. Only ha

lf of

the

sam

ple

com

plet

ed

the

e-ci

g pa

rt (g

rade

s 9–

12)

F: 48%

M: 5

2%

grad

es

9–12

Que

stio

nnai

re,

pen

and

pape

r

Hun

garia

n Fo

cal

Poin

t for

Tob

acco

Co

ntro

l (42

)

Hun

gary

2012

, 201

3Gl

obal

You

th

Toba

cco

Surv

ey2 32

5 (201

2);

4 10

8 (2

013)

A tw

o-stag

e stratifi

ed

clus

ter s

ampl

e de

sign

th

at p

rodu

ced

sam

ples

of

stud

ents in

grade

s 7, 8 or 9

aged

13–

15 y

ears

from

all

Hun

garia

n sc

hool

s

Not

re

port

ed13

–15

ye

ars

Que

stio

nnai

re,

pen

and

pape

r

John

ston

, 201

5 (3

2)

Uni

ted

Stat

es20

14M

onito

ring

the

Futu

re: n

atio

nal

surv

ey re

sult

on

drug

use

41 600

A th

ree-

stag

e ra

ndom

sa

mpl

ing

proc

edur

e us

ed

to s

ecur

e th

e na

tionw

ide

sam

ple

of s

tude

nts

at

each grade

level from 420

sc

hool

s

Not

re

port

ed13

–18

ye

ars

Que

stio

nnai

re,

pen

and

pape

r

Kris

tjans

son,

201

5 (4

6)

Icel

and

2015

Yout

h in

Icel

and

Surv

ey3 47

7M

etho

ds s

imila

r to

the

MTF

sur

vey

and

Euro

pean

Sc

hool

Pro

ject

. The

You

th

in Ic

elan

d su

rvey

s ar

e ad

min

iste

red

to a

ll 10

th

grad

e st

uden

ts (a

ges

15–

16 y

ears

) in

Icel

and

by th

e Ic

elan

dic

Cent

re fo

r Soc

ial

Rese

arch

and

Ana

lysi

s at

Re

ykja

vik

Uni

vers

ity

F: 50.8%

M: 49.2%

15–

16

year

sQ

uest

ionn

aire

, pe

n an

d pa

per



Firs

t aut

hor’s

last

na

me,

yea

rCo

untr

y of

dat

a co

llect

ion

Year

of

data

co

llect

ion

Surv

ey n

ame

nSa

mpl

ing

fram

eSe

x (%

)Ag

e ra

nge

Dat

a co

llect

ion

mod

ality

Lee, 201

4 (3

8)

Repu

blic

of

Kore

a20

1120

11 K

orea

n Yo

uth

Risk

Be

havi

our W

eb

Surv

ey

75 643

A stratifi

ed m

ultis

tage

cl

uste

r sam

plin

g m

etho

d w

as u

sed.

The

sur

vey

was

ad

ministered to 2 400

cl

assr

oom

s (s

econ

dary

sa

mpl

ing

units

) con

sist

ing

of a

ll st

uden

ts in

thre

e cl

asse

s fr

om e

ach

of th

e 40

0 middle an

d 40

0 high

sc

hool

s (p

rimar

y sa

mpl

ing

units

) fro

m 1

29 s

trat

a

F: 47.3%

M: 52.7%

13–18

ye

ars

Web

-bas

ed

ques

tionn

aire

Li, 2

015

(26)

N

ew

Zeal

and

2014

Hea

lth

and

Life

styl

es S

urve

y (H

LS)

2 59

4 bu

t on

ly 3.8%

(n=9

9)

wer

e 15

–17

ye

ars

A multis

tage

, stratified

, cl

uste

red

and

rand

om

prob

abili

ty s

ampl

ing

met

hod,

incl

udin

g an

oversample of M

āori an

d Pa

cific peo

ples. In 20

14,

New

Zea

land

201

3 Ce

nsus

m

esh

bloc

ks (i

.e.,

the

smal

lest

geo

grap

hica

l un

its fo

r whi

ch th

e Ce

nsus

da

ta a

re a

vaila

ble)

wer

e us

ed

F: 5

2.1%

M: 47.9%

15–17

ye

ars

Face

to fa

ce

Mon

tana

Office of

Publ

ic In

stru

ctio

n,

2015

(36)

Uni

ted

Stat

es

(Mon

tana

)

2015

Mon

tana

You

th

Beha

vior

al R

isk

Fact

or

4 48

6 st

uden

ts

from

49

scho

ols

(78%

)

All p

ublic

sch

ools

in

Mon

tana

with

stu

dent

s in

gr

ades

9 th

roug

h 12

wer

e el

igib

le to

be

sele

cted

for

incl

usio

n in

the

sam

ple.

Fi

fty-

four

sch

ools

wer

e ra

ndom

ly s

elec

ted

with

pr

obab

ility

pro

port

iona

l to

enro

lmen

t

F: 51.8%

M: 48.2%

grad

es

9–12

Que

stio

nnai

re,

pen

and

pape

r



Firs

t aut

hor’s

last

na

me,

yea

rCo

untr

y of

dat

a co

llect

ion

Year

of

data

co

llect

ion

Surv

ey n

ame

nSa

mpl

ing

fram

eSe

x (%

)Ag

e ra

nge

Dat

a co

llect

ion

mod

ality

Moo

re, 2

015

(27)

U

nite

d Ki

ngdo

m

(Wal

es)

2014

The

Child

Ex

posu

re to

To

bacc

o Sm

oke

(CH

ETS)

sur

vey

unde

rtak

en in

W

ales

(CH

ETS

Wal

es 2

) and

the 20

14 W

elsh

Hea

lth

Beha

viou

r in

Sch

ool-

aged

Ch

ildre

n (H

BSC)

Su

rvey

(HBS

C W

ales

)

1 49

5 (C

HET

S),

8 95

0 (H

BSC

Wal

es)

CHET

S W

ales

2 s

ampl

ed

from

75 prim

ary scho

ols.

Stat

e-m

aint

aine

d sc

hool

s w

ith y

ear 6

stu

dent

s w

ere

stratifi

ed according

to

high

/low

free

sch

ool m

eal

entit

lem

ent,

and

loca

l ed

ucat

ion

auth

ority

HBS

C W

ales

sam

pled

from

82

secon

dary schoo

ls.

All m

aint

aine

d an

d in

depe

nden

t sec

onda

ry

scho

ols

in W

ales

wer

e stratifi

ed by local a

utho

rity

and

elig

ibili

ty fo

r fre

e sc

hool

mea

ls

(CH

ETS)

F: 5

0.2%

M: 49.8%

(HBS

C W

ales

)

F: 5

0.1%

M: 49.9%

10–

11

year

s (C

HET

S),

11–

16

year

s (H

BSC

Wal

es)

Que

stio

nnai

re,

pen

and

pape

r

NH

S N

atio

nal

Serv

ices

Sco

tlan

d,

2014

(40)

Uni

ted

King

dom

(S

cotl

and)

2013

, 201

4Sc

ottis

h Sc

hool

s Ad

oles

cent

Li

fest

yle

and

Subs

tanc

e U

se

Surv

ey (S

ALSU

S)

33 685

The

surv

ey s

ampl

ed p

upils

in

hig

h sc

hool

(yea

rs

2 an

d 4) in

Scotlan

d.

All l

ocal

aut

horit

y an

d in

depe

nden

tly

fund

ed

scho

ols

with

pup

ils in

the

targ

et a

ge g

roup

s w

ere

elig

ible

for i

nclu

sion

in th

e su

rvey

, with

the

exce

ptio

n of

sch

ools

for c

hild

ren

with

spe

cial

edu

catio

nal

need

s

F: 5

0%

M: 5

0%

13, 1

5 ye

ars

Que

stio

nnai

re,

pen

and

pape

r



Firs

t aut

hor’s

last

na

me,

yea

rCo

untr

y of

dat

a co

llect

ion

Year

of

data

co

llect

ion

Surv

ey n

ame

nSa

mpl

ing

fram

eSe

x (%

)Ag

e ra

nge

Dat

a co

llect

ion

mod

ality

Pepp

er, 2

013

(34)

U

nite

d St

ates

2011

Know

ledg

e N

etw

orks

Kn

owle

dge

Pane

l

228

A su

rvey

com

pany

co

nstr

ucte

d a

natio

nal

pane

l of U

nite

d St

ates

ho

useh

olds

by

usin

g pr

obab

ility

sam

plin

g.

The

surv

ey c

ompa

ny

then

rand

omly

sam

pled

pa

nel m

embe

rs w

ho w

ere

pare

nts

with

son

s ag

ed

11–17

years. Paren

ts who

co

nsen

ted

in 2

010

to W

ave

1 w

ere

reco

ntac

ted

in

Wav

e 2,

whe

re th

eir s

ons

wer

e in

vite

d to

par

ticip

ate

F: 0

%

M: 1

00%

12–18

ye

ars

Web

-bas

ed

ques

tionn

aire

Port

er, 2

015

(33)

U

nite

d St

ates

(F

lorid

a)

2011

, 201

2,

2013

, 201

4D

ata

are

from

the

annu

al 2

011–

2014

Florid

a Yo

uth

Toba

cco

Surv

ey (F

YTS)

12 208

(2

011)

,d 75

428

(2

012)

, 69

923

(201

4)

See

Barn

ett 2

015

F: 49.6%

M: 50.4%

grad

es

6–12

Que

stio

nnai

re,

pen

and

pape

r

Reid

, 201

5 (4

3)

Cana

da20

13Ca

nadi

an T

obac

co,

Alco

hol a

nd

Dru

gs S

urve

y (C

TAD

S)e

2 10

5Th

e sa

mpl

e de

sign

is

a tw

o-ph

ase stratifi

ed

rand

om s

ampl

e of

te

leph

one

num

bers

. In

the

first pha

se, hou

seho

lds

are

sele

cted

usi

ng

rand

om d

igit

dial

ling.

In

the

seco

nd p

hase

, one

or

two

indi

vidu

als

(or n

one)

ar

e se

lect

ed b

ased

upo

n ho

useh

old

com

posi

tion

F: 49%

M: 5

1%

15–

19

year

sQ

uest

ionn

aire

, te

leph

one



Firs

t aut

hor’s

last

na

me,

yea

rCo

untr

y of

dat

a co

llect

ion

Year

of

data

co

llect

ion

Surv

ey n

ame

nSa

mpl

ing

fram

eSe

x (%

)Ag

e ra

nge

Dat

a co

llect

ion

mod

ality

Surís

, 201

5 (4

9)

Switz

erla

nd20

14D

ata

wer

e dr

awn

from

ado

@in

tern

et.c

h, a

lo

ngitu

dina

l st

udy

on In

tern

et

use

base

d on

a

repr

esen

tativ

e sa

mpl

e of

st

uden

ts in

th

e Fr

ench

-sp

eaki

ng p

art o

f Sw

itzer

land

621

A ra

ndom

sam

ple

of 3

5 sc

hool

s w

ere

invi

ted

to p

artic

ipat

e in

the

ado@

inte

rnet

.ch

stud

y in

201

2. A

sub

sam

ple

from

the

ado@

inte

rnet

.ch

stu

dy c

onse

nted

to

bein

g co

ntac

ted

and

wer

e fo

llow

ed u

p in

this

wav

e

F: 50.4%

M: 49.6%

16.2

yea

rsW

eb-b

ased

qu

estio

nnai

re

Wan

g, 2

015

(17)

Ch

ina

(Hon

g Ko

ng S

pe-

cial

Adm

in-

istr

ativ

e Re

gion

)

2012

–20

13Q

uest

ionn

aire

ad

apte

d fr

om

the

Glob

al Y

outh

To

bacc

o Su

rvey

(G

YTS)

45 128

Scho

ol s

ampl

ing

was

stratifi

ed by distric

t, m

ixed

/sin

gle

sex

education, fina

ncial

supp

ort,

and

scho

ol ty

pe

F: 48.6%

M: 51.4%

12–18

ye

ars

Que

stio

nnai

re,

pen

and

pape

r

West, 20

12; F

idler,

2011

(53,

51)

U

nite

d Ki

ngdo

m

(Eng

land

)

2014

, 201

5Sm

okin

g To

olki

t St

udy

1 40

5 (201

4),f

1 33

2 (2

015)

Base

line

surv

eys

wer

e co

nduc

ted

via

mon

thly

cro

ss-s

ectio

nal

hous

ehol

d co

mpu

ter-

assi

sted

inte

rvie

ws

of

approx

imately 1 80

0 ad

ults

age

d 16

and

ove

r in

Eng

land

, usi

ng ra

ndom

lo

catio

n qu

ota

sam

plin

g,

and stratifi

catio

n by A Classificatio

n O

f Res

iden

tial

Nei

ghbo

urho

ods

(ACO

RN)

char

acte

ristic

s

Not

pr

ovid

ed16

–20

ye

arsf

Face

to fa

ce

mailto:[email protected]







Firs

t aut

hor’s

last

na

me,

yea

rCo

untr

y of

dat

a co

llect

ion

Year

of

data

co

llect

ion

Surv

ey n

ame

nSa

mpl

ing

fram

eSe

x (%

)Ag

e ra

nge

Dat

a co

llect

ion

mod

ality

Whi

te, 2

015

(39)

N

ew

Zeal

and

2012

, 201

4Yo

uth

Insi

ghts

Su

rvey

3 12

7 (2

012)

, 2 91

9 (201

4)

A tw

o-st

age

clus

ter

sam

ple

desi

gn to

obt

ain

a na

tiona

lly re

pres

enta

tive

sam

ple

of N

ew Z

eala

nd

year

10

stud

ents

was

use

d

(201

2)

F: 49%

M: 5

1%

(201

4)

F: 49.8%

M: 5

0.2%

14–15

ye

ars

Que

stio

nnai

re,

pen

and

pape

r

a. D

ata

obta

ined

from

web

site

. Cen

tres

for D

isea

se C

ontr

ol a

nd P

reve

ntio

n. S

mok

ing

and

toba

cco

use:

Nat

iona

l You

th T

obac

co S

urve

y (N

YTS)

. [In

tern

et].

Cent

res

for

Disease Con

trol and

Prevention; 201

5 [upd

ated

201

5 Se

p 9; cite

d 20

15 Oct 2]. Av

ailable from

: htt

p://

ww

w.c

dc.g

ov/t

obac

co/d

ata_

stat

istic

s/su

rvey

s/ny

ts/.

b. A

geo

demog

raph

ic classificatio

n system

that describes dem

ograph

ic and

lifestyle profi

les of small g

eograp

hical a

reas.

c. Results of sub

grou

p an

alyses provide

d by autho

rs. O

riginal pub

lication: Gallus S, Lug

o A, Pacifici R, Pichini S, Colom

bo P, Garattin

i S et a

l. E-ciga

rette aw

aren

ess,

use, and

harm perceptions in

Italy: a nationa

l rep

resentative survey. N

icotine an

d Toba

cco Re

search. 201

4;16

(12):154

1–8.

d. D

ata

obta

ined

from

web

site

. Flo

rida

Hea

lth.

201

1 Fl

orid

a Yo

uth

Toba

cco

Surv

ey re

port

s: F

act S

heet

3: Y

outh

sm

okel

ess

toba

cco

use.

[Int

erne

t]. F

lorid

a D

epar

tmen

t

of Health; 201

5 [upd

ated

201

5 Se

p 9; cite

d 20

15 Oct 2]. Av

ailable from

: http://www.floridah

ealth.go

v/statistic

s-an

d-da

ta/survey-da

ta/fl-you

th-tob

acco-survey/_

docu

men

ts/2

011-

stat

e/in

dex1

.htm

l.

e. D

ata

obta

ined

from

web

site

. Gov

ernm

ent o

f Can

ada.

Sum

mar

y of

resu

lts

for 2

013:

Can

adia

n To

bacc

o, A

lcoh

ol a

nd D

rugs

Sur

vey

(CTA

DS)

. [In

tern

et].

Gove

rnm

ent

of Can

ada; 201

5 [upd

ated

201

5 Fe

b 3; cite

d 20

15 Oct 2]. Av

ailable from

: hea

lthy

cana

dian

s.gc

.ca/

scie

nce-

rese

arch

-sci

ence

s-re

cher

ches

/dat

a-do

nnee

s/ct

ads-

ecta

d/

sum

mar

y-so

mm

aire

-201

3-en

g.ph

p.

f. U

pdat

ed re

sult

s fo

r thi

s su

bgro

up (u

npub

lishe

d da

ta) w

ere

prov

ided

by

corr

espo

ndin

g au

thor

. Orig

inal

pub

licat

ion:

Fid

ler J

A, S

haha

b L,

Wes

t O, J

arvi

s M

J, M

cEw

en A

,

Stap

leton JA et a

l. “Th

e sm

oking toolkit study”: a na

tiona

l study of smoking an

d sm

oking cessation in Eng

land

. BMC Pu

blic Health. 201

1;11

(1):1

–9.

http://www.cdc.gov/tobacco/data_statistics/surveys/nyts

http://www.floridahealth.gov/statistics-and-data/survey-data/fl-youth-tobacco-survey/_documents/2011-state/index1.html

http://www.floridahealth.gov/statistics-and-data/survey-data/fl-youth-tobacco-survey/_documents/2011-state/index1.html

healthycanadians.gc.ca/science-research-sciences-recherches/data-donnees/ctads-ectad/summary-sommaire-2013-eng.php

healthycanadians.gc.ca/science-research-sciences-recherches/data-donnees/ctads-ectad/summary-sommaire-2013-eng.php



Tabl

e 2.

Stu

dy c

hara

cter

istic

s of

all

incl

uded

stu

dies

for o

bjec

tive

2

Firs

t aut

hor’s

la

st n

ame,

ye

ar, c

ount

ry

of d

ata

colle

ctio

n

Stud

y de

sign

nSa

mpl

ing

fram

eSe

x (%

)Ag

e,

mea

nO

utco

mes

Dat

a co

llect

ion

mod

ality

Follo

w-

up ti

me

poin

ts

Cova

riate

s ad

just

edRe

sults

Leve

ntha

l, 20

15, U

nite

d St

ates

(54)

Long

itudi

nal,

pros

pect

ive

coho

rt s

tudy

2 50

2St

uden

ts in

pu

blic

hig

h sc

hool

s in

the

Los

Ange

les

met

ropo

litan

ar

ea, c

hose

n be

caus

e of

th

eir d

iver

se

dem

ogra

phic

ch

arac

teris

tics

and

prox

imity

F: 5

3.2%

M:

46.8%

14.06

year

s (9

5% C

I: 14

.04–

14.07)

Use

of

ciga

rett

es

and

othe

r co

m-

bust

ible

ni

cotin

e pr

oduc

ts

in th

e pa

st

six

mon

ths

Surv

eys

eith

er in

pe

rson

, te

leph

one

or In

tern

et

Six

and

12

mon

ths

Soci

odem

ogra

phic

(a

ge, s

ex, r

ace,

hi

gher

par

enta

l ed

ucat

ion)

, en

viro

nmen

tal

fact

ors

(livi

ng

situ

atio

n, p

eer

smok

ing)

and

in

trap

erso

nal

fact

ors

(men

tal h

ealt

h,

pers

onal

ity tr

aits

, ps

ycho

logi

cal

proc

ess)

ass

ocia

ted

with

sm

okin

g, ri

sky

beha

viou

r and

sm

okin

g

SEIS

eve

r use

rs

at b

asel

ine

had

sign

ificantly

incr

ease

d od

ds

of u

sing

any

co

mbu

stib

le

toba

cco

prod

ucts

(AOR 2.73

; 95%

CI: 2.00–

3.73

; P ≤ 0.00

1) and

ci

gare

ttes

(AO

R 1.75

; 95%

CI: 1.10

–2.77

; P = 0.02).

Prim

ack,

20

15, U

nite

d St

ates

(55)

Long

itudi

nal,

pros

pect

ive

coho

rt s

tudy

694

Dat

a co

llect

ed

from

in

divi

dual

s th

at h

ad b

een

part

of a

larg

e na

tiona

lly

repr

esen

tativ

e U

nite

d St

ates

st

udy

F: 5

3.9%

M:

46.1%

19.5

ye

ars

(SD

2.0

) fo

r SEI

S users;

20 y

ears

(SD 2.4)

for n

on-

user

s

Initi

atio

n of

sm

ok-

ing

Tele

phon

e su

rvey

12

mon

ths

Soci

odem

ogra

phic

, pe

rson

al a

nd

envi

ronm

enta

l va

riabl

es

incl

udin

g ag

e, s

ex,

race

, mat

erna

l ed

ucat

ion,

se

nsat

ion-

seek

ing

tend

ency

, par

enta

l sm

okin

g an

d pe

er

smok

ing

Indi

vidu

als

who

wer

e no

n-su

scep

tible

no

n-sm

oker

s an

d SE

IS e

ver u

sers

at

bas

elin

e ha

d sign

ificantly highe

r od

ds o

f usi

ng

ciga

rett

es a

t 12

mon

ths

follo

w-u

p (AOR 8.3; 95%

CI:

1.2–

58.6)



Firs

t aut

hor’s

la

st n

ame,

ye

ar, c

ount

ry

of d

ata

colle

ctio

n

Stud

y de

sign

nSa

mpl

ing

fram

eSe

x (%

)Ag

e,

mea

nO

utco

mes

Dat

a co

llect

ion

mod

ality

Follo

w-

up ti

me

poin

ts

Cova

riate

s ad

just

edRe

sults

Will

s, 20

16,

Haw

aii,

Uni

ted

Stat

es

(56)

Long

itudi

nal,

pros

pect

ive

coho

rt s

tudy

1 30

2Sc

hool

s on

th

e is

land

of

Oah

u,

Haw

aii,

wer

e se

lect

ed to

be

repr

esen

tativ

e of

sch

ool

syst

ems

in

Haw

aii.

Six

of

seve

n in

vite

d sc

hool

s pa

rtic

ipat

ed

and

stud

ents

w

ere

invi

ted

to c

ompl

ete

the

surv

ey

F: 5

3%

M: 4

7%

14.7

year

s (SD 0.7)

Ons

et o

f sm

okin

gPa

per a

nd

penc

il su

rvey

12

mon

ths

The

mul

tivar

iabl

e an

alys

es c

ontr

olle

d fo

r dem

ogra

phic

s, pa

rent

ing

and

pers

onal

ity

varia

bles

and

ad

just

ed fo

r cl

uste

ring

with

in

scho

ols

In a

n im

pute

d an

alys

is, e

ciga

rett

e us

ers

at b

asel

ine

had sign

ificantly

incr

ease

d od

ds o

f ci

gare

tte

use

at

follo

w-u

p (A

OR

1.67

; 95%

CI: 1.17

–2.39

; P < 0.001

)



4.2 Risk of bias 4.2.1 Objective 1Eight of 32 studies satisfied seven of 10 quality assessment criteria, 17 satisfied five or six criteria, and seven satisfied three or four criteria (Figure A4.3). For 22 of the 32 included studies, the study sample was deemed to be representative of the target population. For the majority of these studies, staged cluster sampling and statistical weights were used to ensure the sample was representative of the target population. For the remainder of the studies, sample representativeness was unclear as data weighting was not reported, nor was comparison made between the characteristics of the sample and the target population. Nineteen of the 32 studies described the study setting and the demographics of study subjects in enough detail for comparison to be made to other populations. For all studies apart from four, participant recruitment was rated as appropriate due to random sampling of clusters and participants. In addition, 25 of the 32 studies were deemed to have an adequate sample size. Twenty-two of the 32 studies undertook data weighting to correct for bias due to non-response and ensure sufficient coverage of the sample. For all studies excepted one, the objectivity of the measures was not reported. The reliability of the measures was not reported for all studies. All studies conducted appropriate statistical analysis based on the study aims. The majority (20 of 32) identified and accounted for important confounders and subgroups through regression analysis.

4.2.2 Objective 2As shown in Figure A4.4, none of the longitudinal studies were classified as having a sample representative of the target population. All three studies described the study setting and the demographics of study subjects in detail. The precision of the prevalence estimates in Primack et al. (55) was limited by the small number of participants who reported SEIS use at baseline (n=16). For all studies it was unclear whether the self-reported methods for collecting data on SEIS use and subgroup characteristics were reliable. Also, while Leventhal et al. (54) reported that all measures used in the study had adequate psychometric properties, the validity of the measures used in Primack et al. (55) and Wills (56) was unclear. All studies conducted appropriate statistical analysis, accounting for important confounders associated with cigarette use, such as sex, age, ethnicity and smoking status of family and friends. Appropriately, all studies also used a multiple imputation approach to address attrition bias and examined association only in young people where tobacco smoking was absent at baseline.

4.3 Overall prevalence of SEIS use among young people (objective 1) Prevalence of SEIS ever use between 2013 and 2015. The pooled estimate of the prevalence of SEIS ever use from 20 studies conducted between 2013 and 2015 was 16.4% (95% CI: 12.5–20.6%) (Figure A4.5). Among the 14 studies that reported data by sex, the prevalence was 17.4% (95% CI: 10.9–25%) among males and 14.3% (95% CI: 8.7–21%) in females (data not shown). In the sensitivity analyses (Figure A4.6), including



an additional three studies (49, 50, 52) that did not employ probability sampling (23 studies overall), the prevalence of SEIS ever use was 16.1% (95% CI: 12.6–20.0%) overall, 19.3% (95% CI: 12.5–27.1%) among males (13 studies) and 15.5% (95% CI: 9.9–22.2%) in females (13 studies).

Change in prevalence of ever use between 2008 and 2015. The pooled prevalence of SEIS ever use between 2008 and 2015 by country is shown in Figure A4.7. For four of the five countries where more than one comparable estimate of prevalence was provided over time, prevalence of ever use increased (see Figure A4.7). In the Republic of Korea, prevalence of ever use among 13–19-year-olds increased from 0.5% (95% CI: 0.3–0.8%) in 2008 to 9.4% (95% CI: 9.2–9.6 %) in 2011. In New Zealand, prevalence estimates in 14–15-year-olds increased from 7.0% (95% CI: 6.1–8.0%) to 20.0% (95% CI: 18.6–21.5%) between 2012 and 2014. In Poland, among 15–24-year-olds, prevalence estimates of ever use were 20.9% (95% CI: 20.2–21.6%) in 2010–2011 and 62.1% (95% CI: 59.9–64.2%) in 2013–2014 among 15–19-year-olds. Similarly, in the United States, in nationally representative samples, prevalence of ever use increased from 1.4% (95% CI: 1.2–1.7%) to 3.0% (95% CI: 2.6–3.4%) among middle school children and from 4.7% (95% CI: 4.3–5.1%) to 11.9% (95% CI: 11.3–12.5%) among high school students between 2011 and 2013. Multiple estimates of prevalence over time were also available for Italy, where no difference was observed at the multiple time points (9.2% (95% CI: 5.2–14.7%) in 2013 and 4.4% (95% CI: 1.8–8.8%) in 2015). Different measures however were used for the different data collection years (occasional use in 2014–2015 and ever use for 2013) in Italy.

Prevalence of SEIS current use between 2013 and 2015. The pooled estimate of the prevalence of current SEIS use from 19 studies conducted between 2013 and 2015 was 5.6% (95% CI: 3.4–8.3%) (Figure A4.8). Among the 12 studies that reported data by sex, the prevalence was 6.3% (95% CI: 3.7–9.6%) among males and 4.3% (95% CI: 2.4–6.8%) in females (data not shown). In the sensitivity analyses (Figure A4.9) with an additional five studies (49–52) (24 studies overall), the prevalence of SEIS ever use was 5.5% (95% CI: 3.5–7.9%) overall, 7.4 % (95% CI: 4.5–10.8%) among males (13 studies) and 4.9% (95% CI: 2.8–7.4%) in females (13 studies).

Change in prevalence of current use between 2008 and 2015. The pooled prevalence of current SEIS use between 2008 and 2015 by country is shown in Figure A4.10. In three of the four countries where multiple comparable estimates of prevalence were available over time, prevalence of current use increased. In Poland, data collected on 15–24-year-olds in 2010–2011 reported 8.2% (95% CI: 7.8–8.7%) current use, compared with 29.9% (95% CI: 27.9–32.0%) among adolescents aged 15–19 years in 2013–2014. In the United States, data from the National Youth Tobacco Survey reported that prevalence of current use increased from 0.6% (95% CI: 0.4–0.8%) in 2011 to 3.9% (95% CI: 3.5–4.3%) among middle school students and from 1.5% (95% CI: 1.3–1.8%) to 13.4% (95% CI: 12.8–14.0%) among high school students between 2011 and 2014. In Hungary, however, the prevalence of current use decreased from 13% (95% CI:



11.6–14.4%) in 2012 to 9.0% (95% CI: 8.1–9.9%) in 2013 among mainly young people aged 13–15 years. No changes were observed in Italy from 1.8% (95% CI: 0.4–5.3%) in 2013 to 1.3% (95% CI: 0.2–4.4%) in 2015 among adolescents aged 16–19 years.

4.4 Prevalence among non-smokers (objective 1) Prevalence of SEIS ever use between 2013 and 2015. The pooled estimate of the prevalence of SEIS ever use among non-smokers from 13 studies conducted between 2013 and 2015 was 7.0% (95% CI: 5.1–9.3%) (Figure A4.11). In the sensitivity analyses with an additional three studies (40, 50), the prevalence of SEIS ever use from 15 studies overall was 6.4% (95% CI: 4.6–8.5%) (Figure A4.12).

Change in prevalence of ever use between 2008 and 2015. The pooled prevalence of SEIS ever use among non-smokers between 2008 and 2015 by country is shown in Figure A4.13. National survey data of middle and high school students in the United States reported an increase in prevalence of SEIS ever use from 1.8% (95% CI: 1.6–2.0 %) in 2011 and 4.4% (95% CI: 4.1–4.6%) in 2012. There was no change in prevalence of ever use for Italy, where surveys of 16–19-year-olds reported prevalence of ever use of SEIS by non-smokers of 5.1% (95% CI: 2.1–10.3%) in 2013, 0.7% (95% CI: 0.0–3.9%) in 2014, and 1.4% (95% CI: 0.2–5.0%) in 2015.

Prevalence of SEIS current use between 2013 and 2015. The pooled estimate of the prevalence of current use among non-smokers from 11 studies conducted between 2013 and 2015 was 1.5% (95% CI: 0.3–3.5%) (Figure A4.14). In the sensitivity analyses with an additional four studies (40, 50) (15 studies overall), the prevalence of SEIS ever use was 1.3% (95% CI: 0.4–2.8%) (Figure A4.15).

Change in prevalence of current use between 2008 and 2015. The pooled prevalence of current SEIS use among non-smokers between 2008 and 2015 by country is shown in Figure A4.16. Multiple comparable estimates were available from three countries: Italy, Poland and the United States. In the United States, estimates from the state of Florida found prevalence of current use in non-smokers increased from 0.7% (95% CI: 0.5–1.0%) to 2.8% (95% CI: 2.6–3.0%) among middle school students, and from 0.8% (95% CI: 0.6–1.1%) to 6.9% (95% CI: 6.6–7.2%) among high school students between 2011 and 2014. In United States national samples, the prevalence of current SEIS use was 0.6% (95% CI: 0.5–0.7%) for 11–18-year-olds in 2011, and 1.1% (95% CI: 0.9–1.2) in 2012. In Poland, prevalence was 2.4% (95% CI: 2.1–2.7%) in 2010–2011 and 13.0% (95% CI: 11.2–15.0%) in 2013–2014. No changes were observed in Italy (0% (95% CI: 0.0–2.7%) in 2013, 0% (95% CI: 0.0–2.6%) in 2014, and 0% (95% CI: 0.0–2.6%) in 2015.



4.5 Prevalence among current smokers (objective 1) Prevalence of SEIS ever use between 2013 and 2015. From the 13 studies conducted from 2013, the pooled estimate of SEIS ever use among current tobacco smokers was 54.7% (95% CI: 47.0–62.3%) (Figure A4.17). In the sensitivity analyses with an additional two studies (50) (15 studies overall), the prevalence of SEIS ever use was 53.2% (95% CI: 45.9–60.5%) (Figure A4.18).

Change in prevalence of ever use between 2008 and 2015. The pooled prevalence of SEIS ever use among current-smokers between 2008 and 2015 by country is shown in Figure A4.19. In Italy and the United States, multiple estimates of prevalence of SEIS ever use were provided over time. In the United States, among nationally representative samples of 11–18-year-old students, the prevalence increased from 28.1% (95% CI: 25.0–31.5%) in 2011 to 58.1% (95% CI: 54.8–61.4%) in 2012. In Italy no changes in estimates were observed in 2013 (29.6%; 95% CI: 13.8–50.2%), in 2014 (35.7%; 95% CI: 12.8–64.9%), and in 2015 (26.3%; 95% CI: 9.1–51.2%).

Prevalence of SEIS current use between 2013 and 2015. The pooled estimate of the prevalence of current SEIS use among current tobacco smokers from the 10 studies conducted from 2013 was 19.4% (95% CI: 8.3–33.5%) (Figure A4.20). In the sensitivity analyses with an additional two studies (50) (14 studies overall), the prevalence of SEIS ever use was 17.8% (95% CI: 8.8–28.9%) (Figure A4.21).

Change in the prevalence of current SEIS use between 2008 and 2015. The pooled prevalence of current SEIS use among current smokers between 2008 and 2015 by country is shown in Figure A4.22. For Poland and the United States, multiple comparable estimates of prevalence available across time showed an increase in current use of SEIS among smokers. In Poland, current use in adolescents increased from 15.3% (95% CI: 14.3–16.4%) in 2010–2011 to 57.4% (95% CI: 53.8–61.0%) in 2013–2014. In the United States, among nationally representative samples of 11–18-year-olds, the prevalence increased from 9.8% (95% CI: 7.8–12.1%) in 2011 to 26.5% (95% CI: 23.6–29.5%) in 2012. No changes in prevalence were observed in Italy between 2013 (11.1%; 95% CI: 2.4–29.2%), 2014 (7.1%; 95% CI: 0.2–33.9%) and 2015 (5.3%; 95% CI: 0.1–26.0%).

4.6 Exploring heterogeneity (for objective 1)To explore reasons for the high observed heterogeneity (> 90%) in the pooled estimates of prevalence (between 2008 and 2015), a meta-regression including year of study, age range, regulation, sex and MPOWER score was undertaken for SEIS ever and current use. For prevalence of ever use, the multivariable model including all five covariates accounted for 44% of the observed heterogeneity, where age range (P < 0.05), regulation (P < 0.05) and year of data collection (P < 0.001) were significant. For current SEIS use, year of data collection (P < 0.05) and MPOWER score (P < 0.05) were significant, with the multivariable model including all five covariates accounting for 24% of the identified heterogeneity.



Among non-smokers and current smokers, sex was not included in meta-regression modelling due to lack of available data. For ever use among non-smokers, none of the variables were significantly associated with prevalence heterogeneity. For current SEIS use among non-smokers, year (P < 0.05), age (P < 0.05) and MPOWER score (P < 0.05) were significantly associated with prevalence heterogeneity and accounted for 40% of the identified heterogeneity.

Among current smokers, year (P < 0.05) and regulation (P < 0.05) were significantly associated with the heterogeneity observed in prevalence ever use, and the multivariable model including regulation, year and age accounted for the largest amount (52%) of heterogeneity. For current SEIS use among smokers, only MPOWER score was significant (P < 0.01), and the multivariable model including all four covariates (year, age, regulation and MPOWER score) explained 24% of the observed heterogeneity.

4.7 Objective 2Three studies (54–56) conducted in the United States were included (see Table 2 for study characteristics). Leventhal and colleagues undertook a prospective longitudinal cohort study with 2530 14-year-old English-speaking adolescents, recruited from 10 demographically diverse schools in Los Angeles, who had never used any combustible tobacco products (54). In a repeated measure using generalized mixed model analysis, including only non-tobacco users and adjusting for school, time (six and 12 months) and other potential demographic, environmental and personal covariates, those students who had ever used SEIS at baseline were significantly more likely to report using at least one puff of combustible tobacco products (described as use of a few puffs in the past six months) at 12 months follow-up (OR 2.73; 95% CI: 2.00–3.73; P ≤ 0.001). This association was significant across the examined tobacco products: cigarettes (OR 1.75; 95% CI: 1.10–2.77, P = 0.02), cigars (OR 2.96; 95% CI: 2.00–4.38; P ≤ 0.001) and hookah (OR 2.26; 95% CI: 1.56–3.29; P ≤ 0.001).

Primack and colleagues (55) examined, in a national sample of individuals aged 16–26 years (mean age 19.5 years for SEIS users and 20 years for non-SEIS users), whether being a non-susceptible non-smoker (defined as those reporting that they definitely would not accept a cigarette from a friend and definitely would not smoke in the next year) who used SEIS at baseline (2012/2013) predicted higher experimentation of tobacco cigarette smoking at 12 months follow-up (2013/2014) (55). In the primary analyses imputing for missing data (n=694), a multivariable multinomial logistic regression adjusting for sex, age, race, education level and sensation-seeking tendency found that individuals who smoked SEIS at baseline had significantly higher odds (AOR 8.3; 95% CI: 1.2–58.6%) of progressing from non-susceptible non-smoker to tobacco cigarette smoking one year post baseline. This finding was consistent across multiple sensitivity analyses undertaken by the authors.

Wills and colleagues (56) undertook a school-based survey with 9th and 10th grade students in Hawaii, United States, to examine whether, among never smokers, those



who had used e-cigarettes were more likely to have smoked cigarettes at 12-month follow-up. In the adjusted analysis imputing for missing data, individuals who were e-cigarette users at the first time point had an increased odds (AOR 1.67; 95% CI: 1.17–2.39) of smoking at follow-up.

Pooled analysis of the three studies indicated that SEIS smokers at baseline had an increased adjusted odds ratio (AOR 2.19; 95% CI: 1.46–3.3%; I2 = 59.7%) of being a tobacco cigarette user at follow-up (Figure A4.23).



5. Discussion and conclusion

5.1 DiscussionThis review aimed to describe the prevalence and trends of SEIS use by young people aged between 10 and 20 years; and to examine the association between SEIS use and initiation of tobacco smoking in this group. To describe prevalence and trends, 28 eligible studies of SEIS use among youths that utilized probability sampling were identified. Three longitudinal studies were identified that examined associations between SEIS use and initiation of tobacco smoking.

The prevalence of SEIS use varied considerably within and between countries. Most recent estimates (2013 and 2015) show ever use of SEIS among non-smokers of 7% and prevalence of current use of less than 3%. Among smokers, in countries including Canada, Ireland, New Zealand, the United Kingdom and the United States, more than 50% of smokers had ever used SEIS, while in Poland, the Republic of Korea and the United States, over 20% were current users. Use of SEIS among smokers and non-smokers was reportedly increasing in Poland and in the United States but not for countries such as Italy, where current SEIS use remained relatively stable. In the sensitivity analyses, small increases in prevalence of SEIS current use among smokers and non-smokers were observed.

Observed differences between countries in prevalence and trends could potentially be attributed to differences in regulation governing the promotion of SEIS and their sale to young people. For example, the authors of the Polish studies suggested that the greater increase in SEIS use among Polish adolescents may be due to availability of SEIS in the market, more aggressive marketing of SEIS, and lower levels of regulation (11). The increase in SEIS use has also coincided with reduced prevalence of current tobacco use globally (12, 57). This has led to suggestions that smokers who have quit smoking may potentially be substituting tobacco smoking with SEIS. This review however found that a large proportion of young smokers were current SEIS users, suggesting that smokers may continue to use SEIS concurrently with traditional cigarettes. Findings from the meta-regression suggest that a number of factors, including MPOWER scores, time (year) and participant age, may be associated with prevalence heterogeneity of current/



ever e-cigarette use. These findings however need to be interpreted with caution, as there is likely to be other unmeasured confounders that have not been considered in this analysis. Further longitudinal research assessing the potential impact of MPOWER scores or policy regulation on SEIS use is probably needed to ascertain the impact of such strategies on prevalence of use in youths.

Pooled data from three longitudinal studies (54, 55) found that the use of SEIS by non-smokers more than doubled the odds of experimentation with tobacco smoking within 12 months. Although a number of design limitations exist, these findings support evidence from previous cross-sectional studies and provide early evidence of a positive association between SEIS use and intentions to try tobacco smoking (17–19). The specific pathway by which SEIS use could lead to uptake of tobacco products is unknown. However, the enjoyment of the sensory tobacco-related cues associated with SEIS use (e.g. inhalation, exhalation) (58), the pharmacological effects of consuming nicotine, and the biological and environmental vulnerability during youth and adolescence have been hypothesized to contribute to an increased inclination of SEIS users to try other nicotine-providing tobacco products (59). Further, other researchers suggest that SEIS may act as catalyst, both in supporting initial initiation of SEIS use and facilitating transition to cigarette uptake (16).

These findings need to be interpreted in light of the limitations of this review. First, all included studies utilized self-reported measures of SEIS use. To our knowledge, the validity of such assessment methods has not been established. Measures such as ever use and use in last 30 days may not provide an appropriate indication of established use behaviours (60). Second, for assessment of current use, this review pooled a variety of measures, primarily “regular use” and “use in the last 30 days”, which may have influenced prevalence estimates for some countries. Third, this study also examined tobacco use among non-smokers rather than never smokers. While it is likely that individuals with previous nicotine dependence may have been included, estimates of tobacco use among youths indicates that the majority of non-smoking youths (> 80%) have never smoked (27, 61). Further, there was considerable variability in the definition of smokers in the included studies, which may have resulted in experimenters being classed as current smokers. Fourth, considerable and statistically significant heterogeneity was found among all pooled estimates presented in the review. For prevalence heterogeneity, the I2 exceeded 70% for each case. None of the covariates examined in the meta-regression significantly accounted for the statistical heterogeneity observed in the meta-analyses of current SEIS use, suggesting that other personal or environmental factors may need to be considered. Finally, only three longitudinal studies were identified to examine associations between SEIS use by non-smokers and later initiation of tobacco. Further research is required to substantiate the findings of such studies.



5.2 ConclusionDespite SEIS use among non-smoking young people remaining relatively low in most jurisdictions, the finding of a small but significant longitudinal association between SEIS use and tobacco use and of increasing prevalence of SEIS use among non-smoking young people in some countries supports the need for strategies to discourage SEIS use among non-smokers.



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57. WHO global report on trends in prevalence of tobacco smoking, 2015. Geneva: World Health Organization; 2015.

http://www.smokinginengland.info/reports



58. Rees VW, Kreslake JM, Wayne GF, O Connor RJ, Cummings KM, Connolly GN. Role of cigarette sensory cues in modifying puffing topography. Drug and Alcohol Dependence. 2012;124(1–2):1–10.

59. Kristjansson AL, Sigfusdottir ID. E-cigarette use and relations to tobacco and alcohol use among adolescents. BMC Medicine. 2015;13:103.

60. Amato MS, Boyle RG, Levy D. How to define e-cigarette prevalence? Finding clues in the use frequency distribution. Tobacco Control. 2016;25(e1):e24–9. doi:10.1136/tobaccocontrol-2015-052236.

61. Dutra LM, Glantz SA. High international electronic cigarette use among never smoker adolescents. Journal of Adolescent Health. 2014;55(5):595–7.



Annex 1: Search terms employed in the electronic databases

CINAHL# Searches

S1 e-cig*

S2 electr* cig*

S3 (MH “Electronic Cigarettes”)

S4 vaping

S5 “electronic nicotine”

S6 e-hookah*

S7 electronic hookah*

S8 e-nicotine

S9 S1 OR S2 OR S3 OR S4 OR S5 OR S6 OR S7 OR S8

COCHRANE LIBRARY# Searches

1 MeSH descriptor: [Electronic Cigarettes] this term only

2 e-cig*.mp

3 electr* cig*.mp

4 vaping.mp

5 electronic nicotine.mp

6 e-hookah*.mp

7 electronic hookah*.mp

8 e-nicotine.mp

9 {or #1-#8}



Database(s): Embase 1974 to 2015 Week 31# Searches

1 w-cig*.mp.

2 electr* cig*.mp.

3 vaping.mp.

4 electronic nicotine.mp.

5 e-hookah*.mp.

6 electronic hookah*.mp.

7 e-nicotine.mp.

8 electronic cigarette/

9 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8

Database(s): MEDLINE 1946 to Present with Daily Update# Searches

1 e-cig*.mp.

2 electr* cig.mp.

3 Electronic Cigarettes/

4 vaping.mp.


6 e-hookah*.mp.


8 e-nicotine.mp.

9 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8



Database(s): MEDLINE In-Process & Other Non-Indexed Citations# Searches

1 e-cig*.mp.

2 electr* cig*.mp.

3 vaping.mp.


5 e-hookah*.mp.


7 e-nicotine.mp.

8 electronic cigarette/

9 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8

Database(s): PsycINFO 1806 to July Week 3 2015# Searches

1 w-cig*.mp.

2 electr* cig*.mp.

3 vaping.mp.


5 e-hookah*.mp.


7 e-nicotine.mp.

8 1 or 2 or 3 or 4 or 5 or 6 or 7



Annex 2: Data extraction form (adapted from Cochrane data collection form for intervention reviews)

Citations Author’s name, publication year

Study design Country of study

Year of Data Collection

Type of study

Aims

Survey name/ database

Sample (n) Approached

Eligible

Consent

Analysed

Sampling frame, recruitment method (including sampling unit)

Participants Inclusion criteria

Exclusion criteria

Sex (%)

Age, mean (SD), range

Age range

Race/ethnicity

Socioeconomic status

Other relevant sociodemographic

Subgroups analysed by

Data collection Data collection modality

Measure used

Measures Outcomes (e.g. ever used, current use)

e-cigarette type (if specified)

Total (Final sample) n

Prevalence

Upper 95% CI

Lower 95% CI



Male (Final sample) n

Prevalence

Upper 95% CI

Lower 95% CI

Female (Final sample) n

Prevalence

Upper 95% CI

Lower 95% CI

Other Other results

Analysis and statistical adjustments

Notes



Annex 3: Definition of e-cigarette or SEIS use within included studiesCitation Survey name/

DatabaseEver e-cigarettes user measure

Current e-cigarettes user measure

Alaska Department of Health and Social Services

2015 Alaska Youth Risk Behavior Survey Results

Youth Risk Behaviour Survey

Percentage of students who ever used electronic vapor products (e-cigarettes, e-cigars, e-pipes, vape pipes, vaping pens, e-hookahs, and hookah pens such as blu, NJOY, or Starbuzz)

Percentage of students who currently used electronic vapor products (e-cigarettes, e-cigars, e-pipes, vape pipes, vaping pens, e-hookahs, and hookah pens such as blu, NJOY, or Starbuzz on at least 1 day during the 30 days before the survey)

Anand 2015

E-cigarette use and beliefs among urban public high school students in North Carolina

47-item “High School Questionnaire” 2013 modelled after Monitoring the Future with additional information

Have you ever used an e-cigarette?

• Yes

• No

When was the last time you used an e-cigarette?

• Have never used an e-cigarette

• Today

Arrazola 2014

Tobacco Use Among Middle and High School Students US 2013

2013 National Youth Tobacco Survey (NYTS)

Ever use of electronic cigarettes was determined by asking, “Which of the following tobacco products have you ever tried, even just one time: bidis, kreteks, hookah, snus, dissolvable tobacco, and electronic cigarettes?”

Current use of electronic cigarettes was determined by asking, “During the past 30 days, which of the following products have you used on at least 1 day- bidis, kreteks, hookah, snus, dissolvable tobacco, and electronic cigarettes?”

Arrazola 2015

Tobacco Use Among Middle and High School Students US 2011-2014

2014 National Youth Tobacco Survey (NYTS)

Not reported During the past 30 days, on how many days did you use e-cigarettes such as Blu, 21st Century Smoke, or NJOY?



Citation Survey name/Database

Ever e-cigarettes usermeasure

Current e-cigarettesuser measure

Babineau 2015

Electronic cigarette use among Irish youth: a cross sectional study of prevalence and associated factors

2014 Youth Perception of Plain Packaging Study, a nationally representative school-based survey of 16-17 year olds

Respondents who selected one of the following as statement that best describes them:

• I have tried an e-cigarette once or twice but don’t use one regularly

• I used to smoke e-cigarettes but have given up

Respondents who selected one of the following as statement that best describes them:

• I smoke an e-cigarette at least once a month

• I smoke an e-cigarette at least once a week

• I smoke an e-cigarette every

day.

Barnett 2015

Adolescent electronic cigarette use associations with conventional cigarette and hookah smoking

2013 Florida Youth Tobacco Survey

Have you ever tried, even once, electronic cigarette?

• Yes

• No

During the past 30 days, have you used an electronic cigarette?

• Yes

• No

Cho 2011

Electronic Cigarette smoking experience among adolescents

2008 Health Promotion Fund Project in Korea

Have you ever smoked a cigarette, even one or two puffs?

• Yes

• No

Not reported

Corey 2014

Electronic cigarette use among middle and high school students - United States, 2011-2012

Data are from the annual 2011-2012 National Youth Tobacco Survey (NYTS)

see Arrazola 2014 see Arrazola 2014

Dautzenberg 2013

E-cig : a new tobacco product for school children in Paris

2012 annual survey conducted by Paris San Tabac.


• Yes

• No

Not assessed

Dutra 2014

Electronic cigarettes and conventional cigarette use among U.S. adolescents: a cross-sectional study

National Youth Tobacco Survey (NYTS)

see Arrazola 2014 see Arrazola 2014



Citation Survey name/ Database

Ever e-cigarettes user measure


Eastwood 2015

Electronic cigarette use in young people in Great Britain 2013–2014

YouGov 2013/2014 You said that you have tried an e-cigarette…

Which ONE of the following BEST applies to you?

• I tried smoking a real cigarette before I first tried using an e-cigarette

• I tried using an e-cigarette before I first tried smoking a real cigarette

• I have never smoked a real cigarette but have tried an e-cigarette

• I don’t remember

Those who had heard of e-cigarettes were then asked to describe their experience of e-cigarettes with options range from ‘never use’ to ‘more than once a week’. The following responses were categorised as ‘monthly or more users’:

• I use them sometimes (more than once a month)

• I use them often (more than once a week)

Fidler 2011 The

smoking toolkit study’: a national study of smoking and smoking cessation in England

Smoking Toolkit Study Not assessed Other than yourself, does anyone regularly smoke cigarettes or use an e-cigarette in your presence, such as at your home, work, car or other places that you visit regularly?

• Yes – cigarettes only

• Yes – e-cigarettes only

• Yes – both cigarettes and e-cigarettes

• No – neither cigarettes nor e-cigarettes






Ford 2016

Adolescents’ responses to the promotion and flavouring of e-cigarettes

Youth Tobacco Policy Survey (YTPS)

Ever smokers included those who indicated being regular smokers (at least one cigarette a week), occasional smokers (less than one a week), those who used to smoke and those who had tried smoking only once.

Which of these best describes whether or not you have ever used or tried e-cigarettes?

• I have never used e-cigarettes

• I have only ever tried e-cigarettes once or twice

• I have used e-cigarettes in the past, but I never use them now

• I occasionally use e-cigarettes (less than once a month)

• I use e-cigarettes at least once a month

• I use e-cigarettes at least once a week

Not assessed

Fotiou 2015

Prevalence and correlates of electronic cigarette use among adolescents in Greece: a preliminary cross- sectional analysis of nationwide survey data

2014 Health Behaviour in School-aged Children Survey (HSBC)

Have you ever used an electronic cigarette?

• Never

• Yes

• Only 1-2 times

• Yes more than twice

• Yes more than twice and I use it now

Have you ever used an electronic cigarette?

• Never

• Yes

• Only 1-2 times

• Yes more than twice

• Yes more than twice and I use it now






Gallus 2014

E-Cigarette Awareness, Use, and Harm Perceptions in Italy: A National Representative Survey

Additional analyses from author

Structured questionnaire in the context of a computer assisted personal in-house interview in 2013-2015.

Have you ever heard about e-cigarettes, have you ever tried them or do you have the intention to try them?

• I heard about e-cigarettes and I tried them.

Participants reporting they “have heard about e-cigarettes and have tried them” were labelled as “ever users” of e-cigarettes.

Do you use, occasionally or regularly, the e-cigarette?

• Yes,

occasionally

• Yes, regularly

• I used it in the past

• No

Those who responded yes regularly were classed as current users

Goniewicz 2012

Electronic Cigarette Use Among Teenagers and Young Adults in Poland

The data was collected as part of a national survey on water pipe smoking in 2010-2011, and 2013-2014. Name of survey was unspecified.

Have you ever heard about electronic cigarettes (e-cigarettes)?

• Yes

• No


• Yes

• No

Have you used an e-cigarette at least once in the previous 30 days?

• Yes

• No

Goniewicz 2014

Rise in Electronic Cigarette Use Among Adolescents in Poland

The 2012 and 2011 data was subsample of 2 of the regions included as part of a national survey on water pipe smoking. Name of survey was unspecified. Data

for 2013-2014 were collected from the same 2 regions.

Students were asked whether they had ever smoked or puffed on e-cigarettes (even a single puff).

Students were asked whether they had currently (in the past 30 days) smoked or puffed on e-cigarettes (even a single puff).






Hamilton 2015

Waterpipe use among high school students in Ontario: Demographic and substance use correlates

2013 Ontario Student Drug Use and Health Survey

Have you ever smoked at least one puff from an electronic cigarette?

• Smoking an e-cigarette with nicotine

• Smoking an e-cigarette without

nicotine

• Never smoked but have heard of e-cigarettes

• Never heard of e-cigarettes

Not assessed

Hungarian Focal Point for Tobacco Control. Hungarian and Foreign Data & Statistics: Global Youth Tobacco Survey

Global Youth Tobacco Survey

Not assessed Those who smoked e-cigarette during the past 30 days

Johnston 2014

Key Findings on Adolescent Drug Use

Monitoring the future: National survey 2014 result on drug use

Not reported Prevalence of use in the prior 30 days.

Kristjansson 2015

E-cigarette use and relations to tobacco and alcohol use among adolescents

Youth in Iceland Survey

Not reported Not assessed

Lee 2014

Electronic Cigarette Use Among Korean Adolescents: A Cross-Sectional Study of Market Penetration, Dual Use, and Relationship to Quit Attempts and Former Smoking

2011 Korean Youth Risk Behaviour Web-Survey


• Yes

• No

Have you used e-cigarettes in the past 30 days?

• Yes

• No






Li 2015

The prevalence, correlates and reasons for using electronic cigarettes among New Zealand adults

2014 Health and Lifestyles Survey (HLS)

Have you ever tried an electronic cigarette?

• Yes

• No

Which best describes how often you use an electronic cigarette now?

• At least once a day

• At least once a week

• At least once a month

• Less often than once a month

• Do not use one now

Current use was defined as at least once a month.

Montana Office of Public Instruction 2015 Montana Youth Risk Behaviour Survey High School Results

Montana Youth Behavioural Risk Factor

Electronic vapor products, such as blu, NJOY, or Starbuzz, include e-cigarettes, e-cigars, e-pipes, vape pipes, vaping pens, e-hookahs, and hookah pens.

Have you ever used an electronic vapor product?

• Yes

• No

Electronic vapor products, such as blu, NJOY, or Starbuzz, include e-cigarettes, e-cigars, e-pipes, vape pipes, vaping pens, e-hookahs, and hookah pens.

During the past 30 days, on how many days did you use an electronic vapor product?

• 0 days

• 1 or 2 days

• 3 to 5 days

• 6 to 9 days

• 10 to 19 days

• 20 to 29 days

• All 30 days






Moore 2015

Electronic-cigarette use among young people in Wales: evidence from two cross-sectional surveys

Data from two data sets: the CHild Exposure to Tobacco Smoke (CHETS) survey undertaken in Wales (‘CHETS Wales 2’) in 2014; and 2014 Welsh Health Behaviour in School-aged Children (HBSC) Survey (‘HBSC Wales’).

In CHETS Wales 2, children were asked if they had ever used an e-cigarette, with response options of:

• ‘no’; ‘yes, once’; or

• ‘yes more than once’.

In HBSC Wales, young people were asked if they had ever used an e-cigarette, with at least once a month response options of: ‘I have never used or tried e-cigarettes’; ‘I have used e-cigarettes on a few occasions (1–5 times)’; or ‘I regularly use e-cigarettes (at least once a month)’

Those who selected using cigarettes at least once a month were classed as regular users

National Services Scotland 2014 Scottish Schools Adolescent Lifestyle and Substance Use Survey (SALSUS): SMOKING Among 13 and 15 year olds in Scotland 2013

2013/2014 Scottish Schools Adolescent Lifestyle and Substance Use Survey (SALSUS)

An electronic cigarette (sometimes called an ‘e-cigarette’) is a tube that can look like a normal cigarette, can have a glowing tip and puffs a vapour that looks like smoke but unlike normal cigarettes, they don’t burn tobacco. Now read the following statements carefully and cross the box next to the ONE which best describes you

• I have never used an e-cigarette

• I used to use e-cigarettes but don’t use them anymore

• I have tried an e-cigarette once

• I have tried e-cigarettes a few times

An electronic cigarette (sometimes called an ‘e-cigarette’) is a tube that can look like a normal cigarette, can have a glowing tip and puffs a vapour that looks like smoke but unlike normal cigarettes, they don’t burn tobacco. Now read the following statements carefully and cross the box next to the ONE which best describes you

• I use e-cigarettes sometimes, but no more than once a month

• I use e-cigarettes more than once a month, but less than once a week

• I use e-cigarettes once a week or more






Pepper 2013

Adolescent males’ awareness of and willingness to try electronic cigarettes

Knowledge Networks’ Knowledge Panel


• Yes

• No

Not assessed

Porter 2015

Electronic cigarette and traditional cigarette use among middle and high school students in Florida, 2011-2014

Data are from the annual 2011–2014 Florida Youth Tobacco Survey (FYTS)

Have you ever tried once using electronic cigarettes?

• Yes

• No

During the past 30 days have you used an electronic cigarette?

• Yes

• No

Reid 2015

Tobacco Use in Canada: Patterns and Trends, 2015 Edition.

2015 Canadian Tobacco, Alcohol and Drugs Survey (CTADS)

Have you ever tried an electronic cigarette, also known as an e-cigarette?

• Yes

• No

In the past 30 days did you use an electronic cigarette, also known as an e-cigarette?

• Yes

• No

Surís 2015

Reasons to use e-cigarettes and associations with other substances among adolescents in Switzerland

Data were drawn from ado @ internet.ch, a longitudinal study on Internet use based on a representative sample of students in the French- speaking part of Switzerland.

Have you ever tried electronic cigarettes?

• Never

• Only once

• Several times

• Regularly

Those who selected ‘only once’ were classed as experimenters.


• Never

• Only once

• Several times

• Regularly

Those who selected ‘several times’ and ‘regularly’ were classed as users.

Wang 2015

Electronic cigarette use and its association with smoking in Hong Kong Chinese adolescents

A 2012-2013, anonymous, self- administered questionnaire in Chinese adapted from the Global Youth Tobacco Survey (GYTS) (The GTSS Collaborative Group, 2006)

Not assessed Only one questions on e-cigarettes use in the past 30 days (yes vs no) was used. No levels of use were specified and students were expected to report any use including even 1 puff.

White 2015

Tripling Use of Electronic Cigarettes Among New Zealand Adolescents Between 2012 and 2014

2012 & 2014 The Youth Insights Survey


• Yes

• No

Not assessed



Annex 4: List of FiguresFigure 1: PRISMA diagram outlining study selection forprevalence of e-cigarette use (Objective 1)

From: Moher D, Liberati A, Tetzlaff J, Altman DG, The PRISMA Group (2009). Preferred Reporting Items for Systematic Reviews and Meta-Analyses: The PRISMA Statement. PLoS Med 6(6): e1000097. doi:10.1371/journal.pmed1000097

For more information, visit www.prisma-statement.org.

Figure 1: PRISMA diagram outlining study selection for prevalence of e-cigarette use (Objective 1)

Records identified through database searching

(n = 3547 )

Scre

enin

g In

clud

ed

Elig

ibili

ty

Iden

tific

atio

n

Additional records identified through other sources

(n = 35)

Records after duplicates removed (n = 2281)

Records screened (n = 2281)

Records excluded (n = 2146)

Full-text articles assessed for eligibility

(n = 135)

Full-text articles excluded, with reasons

(n = 107) Adults (n=55) Did not report on prevalence of e-cigarette use (n=4) Did not use probability sampling (n=4) Not representativie of the region (n=14) Not an empirical study (n=12) Included findings previously reported in other published papers (n=18)

Studies included in qualitative synthesis

(n = 28)

Studies included in quantitative synthesis

(meta-analysis) (n = 28)

From: Moher D, Liberati A, Tetzlaff J, Altman DG, The PRISMA Group (2009). Preferred Reporting Items for

Systematic Reviews and Meta-Analyses: The PRISMA Statement. PLoS Med 6(6): e1000097. doi:10.1371/

journal.pmed1000097


www.prisma-statement.org



Figure 2: PRISMA diagram outlining study selection forassociation of e-cigarette use and tobacco uptake (Objective 2)

From: Moher D, Liberati A, Tetzlaff J, Altman DG, The PRISMA Group (2009). Preferred Reporting Items for

Systematic Reviews and Meta-Analyses: The PRISMA Statement. PLoS Med 6(6): e1000097. doi:10.1371/

journal.pmed1000097


From: Moher D, Liberati A, Tetzlaff J, Altman DG, The PRISMA Group (2009). Preferred Reporting Items for Systematic Reviews and Meta-Analyses: The PRISMA Statement. PLoS Med 6(6): e1000097. doi:10.1371/journal.pmed1000097


Figure 2: PRISMA diagram outlining study selection for association of e-cigarette use and tobacco uptake (Objective 2)

Records identified through database searching

(n = 3547 )

Scre

enin

g In

clud

ed

Elig

ibili

ty

Iden

tific

atio

n

Additional records identified through other sources

(n = 35)

Records after duplicates removed (n = 2281)

Records screened (n = 2281)

Records excluded (n = 2162)

Full-text articles assessed for eligibility

(n = 119)

Full-text articles excluded, with reasons

(n = 116) Did not examine e-cigarette use (n=5) Not undertaken in youth/adolescents (n=5) Did not examine association with tobacco/cigarette smoking (n=26) Conference abstract of published study (n=1) Not relevant study design (n=79)

Studies included in qualitative synthesis

(n = 3 )

Studies included in quantitative synthesis

(meta-analysis) (n = 3 )

www.prisma-statement.org



Figure 3: Quality assessment for individual cross-sectional studies included for Objective 1

*Eastwood 2014, Ford 2015, Suris

2015, West 2012 were included in

the sensitivity analyses.

Yes No Unsure



Figure 4: Quality assessment for individual longitudinal studies included for Objective 2

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), 20

14]

Babi

neau

[Ire

land

, 201

4]

Arra

zola

[US

NYT

S, 2

013]

Gallu

s [It

aly,

201

3]

Gallu

s [It

aly,

201

5]

Ham

ilton

[Can

ada

(Ont

ario

), 20

15]

SALS

US

[UK

(Sco

tlan

d), 2

013-

2014

]

Arra

zola

[US

NYT

S, 2

013]

Kris

tjans

son

[Icel

and,

201

5]

Ford

[UK

(Eng

land

), 20

15]

Alas

ka [U

S (A

lask

a), 2

015]

Whi

te [N

ew Z

eala

nd, 2

014]

Suris

[Sw

itzer

land

, 201

5]

Mon

tana

[US

(Mon

tana

), 20

15]

Gallu

s [It

aly,

201

4]

Port

er [U

S (F

lorid

a), 2

014]

Sour

ce

Port

er [U

S (F

lorid

a), 2

014]

Moo

re [U

K (W

ales

), 20

14]

Fotio

u [G

reec

e, 2

014]

Li [N

ew Z

eala

nd, 2

014]

Goni

ewic

z [P

olan

d, 2

013-

2014

]

East

woo

d [U

K (E

ngla

nd),

2013

]

Anan

d [U

S (C

alifo

rnia

), 20

13]

Reid

[Can

ada,

201

3]

11-1

8

11-1

8

10-1

1

16-1

7

15-1

8

16-1

9

16-1

9

14-1

8

13-1

5

11-1

4

15-1

6

11-1

6

14-1

8

14-1

5

16 14-1

8

16-1

9

11-1

4

rang

e

15-1

8

11-1

6

15 15-1

7

15-1

9

11-1

8

15-1

8

15-1

9

Age

1098

170

87196

1213

15 7422

3487

243

587

145

512

584

267

2292

7 3143

(n)

6749

1018

219

201223

100

421

3284

Out

com

e

1261

5

2068

1601

821

1019

0

163

160

2892

3205

1

8111

3477

1205

1418

2919

621

4486

153

3697

9

part

icip

ants

3292

1

9055

1320

991970

2177

2769

1658

6

Num

ber o

f

16.1

(12.

6, 2

0.0)

8.7

(8.2

, 9.2

)

8.2

(7.1

, 9.5

)

5.4

(4.4

, 6.7

)

23.9

(21.

0, 2

6.9)

11.9

(11.

3, 1

2.5)

9.2

(5.2

, 14.

7)

4.4

(1.8

, 8.8

)

14.6

(13.

3, 1

5.9)

10.9

(10.

5, 1

1.2)

3.0

(2.6

, 3.4

)

16.9

(15.

7, 1

8.2)

12.0

(10.

2, 1

4.0)

36.1

(33.

6, 3

8.7)

20.0

(18.

6, 2

1.5)

43.0

(39.

1, 4

7.0)

51.1

(49.

6, 5

2.6)

4.6

(1.9

, 9.2

)

8.5

(8.2

, 8.8

)

ES (9

5% C

I)

20.5

(20.

1, 2

0.9)

11.2

(10.

6, 1

1.9)

16.6

(14.

6, 1

8.7)

20.2

(12.

8, 2

9.5)

62.1

(59.

9, 6

4.2)

4.6

(3.8

, 5.6

)

15.2

(13.

9, 1

6.6)

19.8

(19.

2, 2

0.4)

100.

00

3.92

3.90

3.89

3.86

3.92

3.60

3.59

3.91

3.92

3.92

3.91

3.88

3.88

3.91

3.83

3.91

3.58

3.92

Wei

ght

3.92

3.92

3.88

3.41

3.90

3.90

3.90

3.92

%

16.1

(12.

6, 2

0.0)

8.7

(8.2

, 9.2

)

8.2

(7.1

, 9.5

)

5.4

(4.4

, 6.7

)

23.9

(21.

0, 2

6.9)

11.9

(11.

3, 1

2.5)

9.2

(5.2

, 14.

7)

4.4

(1.8

, 8.8

)

14.6

(13.

3, 1

5.9)

10.9

(10.

5, 1

1.2)

3.0

(2.6

, 3.4

)

16.9

(15.

7, 1

8.2)

12.0

(10.

2, 1

4.0)

36.1

(33.

6, 3

8.7)

20.0

(18.

6, 2

1.5)

43.0

(39.

1, 4

7.0)

51.1

(49.

6, 5

2.6)

4.6

(1.9

, 9.2

)

8.5

(8.2

, 8.8

)

ES (9

5% C

I)

20.5

(20.

1, 2

0.9)

11.2

(10.

6, 1

1.9)

16.6

(14.

6, 1

8.7)

20.2

(12.

8, 2

9.5)

62.1

(59.

9, 6

4.2)

4.6

(3.8

, 5.6

)

15.2

(13.

9, 1

6.6)

19.8

(19.

2, 2

0.4)

100.

00

3.92

3.90

3.89

3.86

3.92

3.60

3.59

3.91

3.92

3.92

3.91

3.88

3.88

3.91

3.83

3.91

3.58

3.92

Wei

ght

3.92

3.92

3.88

3.41

3.90

3.90

3.90

3.92

%

010

2030

4060

80

Heterogeneity between groups: p = 0.000Overall (I^2 = 99.8%, p = 0.0);

Subtotal (I^2 = 99.9%, p = 0.0)

Porter

Reid

Goniewicz

Iceland

Corey

Porter

Korea

Gallus

Subtotal (I^2 = 45.9%, p = 0.2)

US

Corey

Poland

Gallus

Arrazola

Greece

Anand

Moore

Goniewicz

Li

Montana

Lee

Hamilton

Barnett

Ireland

Subtotal (I^2 = 96.9%, p = 0.0)

Alaska

Subtotal (I^2 = 99.2%, p = 0.0)

Gallus

Porter

WhiteNew Zealand

Cho

Subtotal (I^2 = 72.9%, p = 0.1)

Kristjansson

Arrazola

White

SALSUSUK

Canada (Ontario)

Corey

Babineau

Fotiou

Porter

PorterCoreyPorter

Moore

Canada

DautzenbergFrance

Pepper

Subtotal (I^2 = 99.6%, p = 0.0)

Author

Italy

US (Florida)

Canada

Poland

US NYTS

US (Florida)

Italy

US NYTS

Italy

US NYTSUS (California)

UK (Wales)

Poland

New Zealand

US (Montana)

Korea

Canada (Ontario)

US (Florida)

US (Alaska)

Italy

US (Florida)

New Zealand

Korea

Iceland

US NYTS

New Zealand

UK (Scotland)

US NYTS

Ireland

Greece

US (Florida)

US (Florida)US NYTSUS (Florida)

UK (Wales)

France (Paris)

US National

Country

2014

2013

2010-2011

2012

2011

2014

2011

2015

20132013

2014

2013-2014

2014

2015

2011

2015

2013

2015

2013

2011

2012

2008

2015

2013

2014

2013-2014

2011

2014

2014

2014

2012

Data

20122012

2014

2012

2011

collection

15-18

15-19

15-24

15-18

15-18

16-19

15-18

16-19

15-1815-18

11-16

15-19

15-17

14-18

13-18

14-18

11-18

14-18

16-19

11-14

14-15

13-19

15-16

11-14

14-15

13-15

11-14

16-17

15

11-14

11-14

Age

11-1415-18

10-11

12-19

12-18

range

32921

16586

13787

12899

6163

153

9720

160

101902769

9055

1970

99

4486

75643

2892

12615

1418

163

6045

3127

4341

3477

8111

2919

32051

8880

821

1320

36979

369891166736439

1601

3409

228

N

6749

3284

2881

1290

370

7

457

7

1213421

1018

1223

20

2292

7110

422

1098

512

15

181

219

22

587

243

584

3487

124

196

219

3143

1443

Outcome

3153061

87

277

2

(n)

11.4 (9.0, 14.0)

9.3 (6.1, 13.2)

20.5 (20.1, 20.9)

19.8 (19.2, 20.4)

20.9 (20.2, 21.6)

10.0 (9.5, 10.5)

6.0 (5.4, 6.6)

4.6 (1.9, 9.2)

5.9 (3.3, 9.2)

4.7 (4.3, 5.1)

4.4 (1.8, 8.8)

11.9 (11.3, 12.5)15.2 (13.9, 16.6)

11.2 (10.6, 11.9)

62.1 (59.9, 64.2)

20.2 (12.8, 29.5)

51.1 (49.6, 52.6)

9.4 (9.2, 9.6)

14.6 (13.3, 15.9)

8.7 (8.2, 9.2)

9.2 (7.2, 11.3)

36.1 (33.6, 38.7)

14.9 (5.5, 27.7)

9.2 (5.2, 14.7)

3.0 (2.6, 3.5)

7.0 (6.1, 8.0)

0.5 (0.3, 0.8)

8.6 (8.5, 8.8)

16.9 (15.7, 18.2)

3.0 (2.6, 3.4)

20.0 (18.6, 21.5)

10.9 (10.5, 11.2)

1.4 (1.2, 1.7)

23.9 (21.0, 26.9)

16.6 (14.6, 18.7)

8.5 (8.2, 8.8)

3.9 (3.7, 4.1)2.7 (2.4, 3.0)8.4 (8.1, 8.7)

5.4 (4.4, 6.7)

8.1 (7.2, 9.1)

0.9 (0.1, 3.1)

25.5 (24.8, 26.1)

ES (95% CI)

11.4 (9.0, 14.0)

9.3 (6.1, 13.2)

20.5 (20.1, 20.9)

19.8 (19.2, 20.4)

20.9 (20.2, 21.6)

10.0 (9.5, 10.5)

6.0 (5.4, 6.6)

4.6 (1.9, 9.2)

5.9 (3.3, 9.2)

4.7 (4.3, 5.1)

4.4 (1.8, 8.8)

11.9 (11.3, 12.5)15.2 (13.9, 16.6)

11.2 (10.6, 11.9)

62.1 (59.9, 64.2)

20.2 (12.8, 29.5)

51.1 (49.6, 52.6)

9.4 (9.2, 9.6)

14.6 (13.3, 15.9)

8.7 (8.2, 9.2)

9.2 (7.2, 11.3)

36.1 (33.6, 38.7)

14.9 (5.5, 27.7)

9.2 (5.2, 14.7)

3.0 (2.6, 3.5)

7.0 (6.1, 8.0)

0.5 (0.3, 0.8)

8.6 (8.5, 8.8)

16.9 (15.7, 18.2)

3.0 (2.6, 3.4)

20.0 (18.6, 21.5)

10.9 (10.5, 11.2)

1.4 (1.2, 1.7)

23.9 (21.0, 26.9)

16.6 (14.6, 18.7)

8.5 (8.2, 8.8)

3.9 (3.7, 4.1)2.7 (2.4, 3.0)8.4 (8.1, 8.7)

5.4 (4.4, 6.7)

8.1 (7.2, 9.1)

0.9 (0.1, 3.1)

25.5 (24.8, 26.1)

ES (95% CI)

0 10 20 30 40 60 80



Figure 7: Pooled analysis of ever e-cigarette use among youth by country (2008-2015)


Subtotal (I^2 = 99.9%, p = 0.0)

Porter

Reid

Goniewicz

Iceland

Corey

Porter

Korea

Gallus

Subtotal (I^2 = 45.9%, p = 0.2)

US

Corey

Poland

Gallus

Arrazola

Greece

Anand

Moore

Goniewicz

Li

Montana

Lee

Hamilton

Barnett

Ireland

Subtotal (I^2 = 96.9%, p = 0.0)

Alaska

Subtotal (I^2 = 99.2%, p = 0.0)

Gallus

Porter

WhiteNew Zealand

Cho

Subtotal (I^2 = 72.9%, p = 0.1)

Kristjansson

Arrazola

White

SALSUSUK

Canada (Ontario)

Corey

Babineau

Fotiou

Porter

PorterCoreyPorter

Moore

Canada

DautzenbergFrance

Pepper

Subtotal (I^2 = 99.6%, p = 0.0)

Author

Italy

US (Florida)

Canada

Poland

US NYTS

US (Florida)

Italy

US NYTS

Italy

US NYTSUS (California)

UK (Wales)

Poland

New Zealand

US (Montana)

Korea

Canada (Ontario)

US (Florida)

US (Alaska)

Italy

US (Florida)

New Zealand

Korea

Iceland

US NYTS

New Zealand

UK (Scotland)

US NYTS

Ireland

Greece

US (Florida)

US (Florida)US NYTSUS (Florida)

UK (Wales)

France (Paris)

US National

Country

2014

2013

2010-2011

2012

2011

2014

2011

2015

20132013

2014

2013-2014

2014

2015

2011

2015

2013

2015

2013

2011

2012

2008

2015

2013

2014

2013-2014

2011

2014

2014

2014

2012

Data

20122012

2014

2012

2011

collection

15-18

15-19

15-24

15-18

15-18

16-19

15-18

16-19

15-1815-18

11-16

15-19

15-17

14-18

13-18

14-18

11-18

14-18

16-19

11-14

14-15

13-19

15-16

11-14

14-15

13-15

11-14

16-17

15

11-14

11-14

Age

11-1415-18

10-11

12-19

12-18

range

32921

16586

13787

12899

6163

153

9720

160

101902769

9055

1970

99

4486

75643

2892

12615

1418

163

6045

3127

4341

3477

8111

2919

32051

8880

821

1320

36979

369891166736439

1601

3409

228

N

6749

3284

2881

1290

370

7

457

7

1213421

1018

1223

20

2292

7110

422

1098

512

15

181

219

22

587

243

584

3487

124

196

219

3143

1443

Outcome

3153061

87

277

2

(n)

11.4 (9.0, 14.0)

9.3 (6.1, 13.2)

20.5 (20.1, 20.9)

19.8 (19.2, 20.4)

20.9 (20.2, 21.6)

10.0 (9.5, 10.5)

6.0 (5.4, 6.6)

4.6 (1.9, 9.2)

5.9 (3.3, 9.2)

4.7 (4.3, 5.1)

4.4 (1.8, 8.8)

11.9 (11.3, 12.5)15.2 (13.9, 16.6)

11.2 (10.6, 11.9)

62.1 (59.9, 64.2)

20.2 (12.8, 29.5)

51.1 (49.6, 52.6)

9.4 (9.2, 9.6)

14.6 (13.3, 15.9)

8.7 (8.2, 9.2)

9.2 (7.2, 11.3)

36.1 (33.6, 38.7)

14.9 (5.5, 27.7)

9.2 (5.2, 14.7)

3.0 (2.6, 3.5)

7.0 (6.1, 8.0)

0.5 (0.3, 0.8)

8.6 (8.5, 8.8)

16.9 (15.7, 18.2)

3.0 (2.6, 3.4)

20.0 (18.6, 21.5)

10.9 (10.5, 11.2)

1.4 (1.2, 1.7)

23.9 (21.0, 26.9)

16.6 (14.6, 18.7)

8.5 (8.2, 8.8)

3.9 (3.7, 4.1)2.7 (2.4, 3.0)8.4 (8.1, 8.7)

5.4 (4.4, 6.7)

8.1 (7.2, 9.1)

0.9 (0.1, 3.1)

25.5 (24.8, 26.1)

ES (95% CI)

11.4 (9.0, 14.0)

9.3 (6.1, 13.2)

20.5 (20.1, 20.9)

19.8 (19.2, 20.4)

20.9 (20.2, 21.6)

10.0 (9.5, 10.5)

6.0 (5.4, 6.6)

4.6 (1.9, 9.2)

5.9 (3.3, 9.2)

4.7 (4.3, 5.1)

4.4 (1.8, 8.8)

11.9 (11.3, 12.5)15.2 (13.9, 16.6)

11.2 (10.6, 11.9)

62.1 (59.9, 64.2)

20.2 (12.8, 29.5)

51.1 (49.6, 52.6)

9.4 (9.2, 9.6)

14.6 (13.3, 15.9)

8.7 (8.2, 9.2)

9.2 (7.2, 11.3)

36.1 (33.6, 38.7)

14.9 (5.5, 27.7)

9.2 (5.2, 14.7)

3.0 (2.6, 3.5)

7.0 (6.1, 8.0)

0.5 (0.3, 0.8)

8.6 (8.5, 8.8)

16.9 (15.7, 18.2)

3.0 (2.6, 3.4)

20.0 (18.6, 21.5)

10.9 (10.5, 11.2)

1.4 (1.2, 1.7)

23.9 (21.0, 26.9)

16.6 (14.6, 18.7)

8.5 (8.2, 8.8)

3.9 (3.7, 4.1)2.7 (2.4, 3.0)8.4 (8.1, 8.7)

5.4 (4.4, 6.7)

8.1 (7.2, 9.1)

0.9 (0.1, 3.1)

25.5 (24.8, 26.1)

ES (95% CI)

0 10 20 30 40 60 80


Figu

re 9

: Sen

sitiv

ity a

naly

sis

of c

urre

nt e

-cig

aret

te u

se a

mon

g yo

uth

from

201

3-20

15

Figu

re 8

: Poo

led

anal

ysis

of c

urre

nt e

-cig

aret

te u

se a

mon

g yo

uth

from

201

3-20

15

Ove

rall

(I^2

= 9

9.8%

, p =

0.0

)

Gallu

s

Arra

zola

John

ston

Gallu

s

Reid

Gallu

s

Mon

tana

Alas

ka

Port

er

Fotio

u

Arra

zola

Anan

d

Port

er

Moo

re

Babi

neau

Auth

or

Arra

zola

SALS

US

Arra

zola

Barn

ett

Goni

ewic

z

Hun

gary

Li

Ital

y

US

NYT

S

US

Ital

y

Cana

da

Ital

y

US

(Mon

tana

)

US

(Ala

ska)

US

(Flo

rida)

Gree

ce

US

NYT

S

US

(Cal

iforn

ia)

US

(Flo

rida)

UK

(Wal

es)

Irel

and

Coun

try

US

NYT

S

UK

(Sco

tlan

d)

US

NYT

S

US

(Flo

rida)

Pola

nd

Hun

gary

New

Zea

land

2013

2013

2014

2014

2013

2015

2015

2015

2014

2014

2014

2013

2014

2014

2014

colle

ctio

n

2014

2013

-201

4

2013

2013

2013

-201

4

2013

2014

Dat

a

16-1

9

15-1

8

13-1

8

16-1

9

15-1

9

16-1

9

14-1

8

14-1

8

11-1

4

15 15-1

8

15-1

8

15-1

8

11-1

6

16-1

7

rang

e

11-1

4

13-1

5

11-1

4

11-1

8

15-1

9

13-1

5

15-1

7

Age

163

1019

0

4160

0

153

1658

6

160

4486

1418

3697

9

1320

1145

9

2769

3292

1

9022

821

N 1041

9

3205

1

8111

1261

5

1970

4018

99

3 459

5782

1431

2 1323

251

1479

7 1536

205

3555

125

26(n)

406

276

89492

589

362

0Out

com

e

5.6

(3.4

, 8.3

)

1.8

(0.4

, 5.3

)

4.5

(4.1

, 4.9

)

13.9

(13.

6, 1

4.2)

0.7

(0.0

, 3.6

)

2.6

(2.4

, 2.9

)

1.3

(0.2

, 4.4

)

29.5

(28.

2, 3

0.9)

17.7

(15.

7, 1

9.8)

4.0

(3.8

, 4.2

)

0.5

(0.2

, 1.1

)

13.4

(12.

8, 1

4.0)

7.4

(6.5

, 8.4

)

10.8

(10.

5, 1

1.1)

1.4

(1.2

, 1.6

)

3.2

(2.1

, 4.6

)

ES (9

5% C

I)

3.9

(3.5

, 4.3

)

0.9

(0.8

, 1.0

)

1.1

(0.9

, 1.3

)

3.9

(3.6

, 4.3

)

29.9

(27.

9, 3

2.0)

9.0

(8.1

, 9.9

)

0.0

(0.0

, 3.7

)

5.6

(3.4

, 8.3

)

1.8

(0.4

, 5.3

)

4.5

(4.1

, 4.9

)

13.9

(13.

6, 1

4.2)

0.7

(0.0

, 3.6

)

2.6

(2.4

, 2.9

)

1.3

(0.2

, 4.4

)

29.5

(28.

2, 3

0.9)

17.7

(15.

7, 1

9.8)

4.0

(3.8

, 4.2

)

0.5

(0.2

, 1.1

)

13.4

(12.

8, 1

4.0)

7.4

(6.5

, 8.4

)

10.8

(10.

5, 1

1.1)

1.4

(1.2

, 1.6

)

3.2

(2.1

, 4.6

)

ES (9

5% C

I)

3.9

(3.5

, 4.3

)

0.9

(0.8

, 1.0

)

1.1

(0.9

, 1.3

)

3.9

(3.6

, 4.3

)

29.9

(27.

9, 3

2.0)

9.0

(8.1

, 9.9

)

0.0

(0.0

, 3.7

)

010

2030

40



Figu

re 9

: Sen

sitiv

ity a

naly

sis

of c

urre

nt e

-cig

aret

te u

se a

mon

g yo

uth

from

201

3-20

15

Ove

rall

(I^2

= 9

9.8%

, p =

0.0

)

Gallu

s

Arra

zola

John

ston

Gallu

s

Reid

Gallu

s

Mon

tana

Alas

ka

Port

er

Fotio

u

Arra

zola

Anan

d

Port

er

Moo

re

Babi

neau

Auth

or

Arra

zola

SALS

US

Arra

zola

Barn

ett

Goni

ewic

z

Hun

gary

Li

Ital

y

US

NYT

S

US

Ital

y

Cana

da

Ital

y

US

(Mon

tana

)

US

(Ala

ska)

US

(Flo

rida)

Gree

ce

US

NYT

S

US

(Cal

iforn

ia)

US

(Flo

rida)

UK

(Wal

es)

Irel

and

Coun

try

US

NYT

S

UK

(Sco

tlan

d)

US

NYT

S

US

(Flo

rida)

Pola

nd

Hun

gary

New

Zea

land

2013

2013

2014

2014

2013

2015

2015

2015

2014

2014

2014

2013

2014

2014

2014

colle

ctio

n

2014

2013

-201

4

2013

2013

2013

-201

4

2013

2014

Dat

a

16-1

9

15-1

8

13-1

8

16-1

9

15-1

9

16-1

9

14-1

8

14-1

8

11-1

4

15 15-1

8

15-1

8

15-1

8

11-1

6

16-1

7

rang

e

11-1

4

13-1

5

11-1

4

11-1

8

15-1

9

13-1

5

15-1

7

Age

163

1019

0

4160

0

153

1658

6

160

4486

1418

3697

9

1320

1145

9

2769

3292

1

9022

821

N 1041

9

3205

1

8111

1261

5

1970

4018

99

3 459

5782

1431

2 1323

251

1479

7 1536

205

3555

125

26(n)

406

276

89492

589

362

0Out

com

e

5.6

(3.4

, 8.3

)

1.8

(0.4

, 5.3

)

4.5

(4.1

, 4.9

)

13.9

(13.

6, 1

4.2)

0.7

(0.0

, 3.6

)

2.6

(2.4

, 2.9

)

1.3

(0.2

, 4.4

)

29.5

(28.

2, 3

0.9)

17.7

(15.

7, 1

9.8)

4.0

(3.8

, 4.2

)

0.5

(0.2

, 1.1

)

13.4

(12.

8, 1

4.0)

7.4

(6.5

, 8.4

)

10.8

(10.

5, 1

1.1)

1.4

(1.2

, 1.6

)

3.2

(2.1

, 4.6

)

ES (9

5% C

I)

3.9

(3.5

, 4.3

)

0.9

(0.8

, 1.0

)

1.1

(0.9

, 1.3

)

3.9

(3.6

, 4.3

)

29.9

(27.

9, 3

2.0)

9.0

(8.1

, 9.9

)

0.0

(0.0

, 3.7

)

5.6

(3.4

, 8.3

)

1.8

(0.4

, 5.3

)

4.5

(4.1

, 4.9

)

13.9

(13.

6, 1

4.2)

0.7

(0.0

, 3.6

)

2.6

(2.4

, 2.9

)

1.3

(0.2

, 4.4

)

29.5

(28.

2, 3

0.9)

17.7

(15.

7, 1

9.8)

4.0

(3.8

, 4.2

)

0.5

(0.2

, 1.1

)

13.4

(12.

8, 1

4.0)

7.4

(6.5

, 8.4

)

10.8

(10.

5, 1

1.1)

1.4

(1.2

, 1.6

)

3.2

(2.1

, 4.6

)

ES (9

5% C

I)

3.9

(3.5

, 4.3

)

0.9

(0.8

, 1.0

)

1.1

(0.9

, 1.3

)

3.9

(3.6

, 4.3

)

29.9

(27.

9, 3

2.0)

9.0

(8.1

, 9.9

)

0.0

(0.0

, 3.7

)

010

2030

40

Ove

rall

(I^2

= 9

9.8%

, p =

0.0

)

Moo

re [U

K (W

ales

), 20

14]

Gallu

s [It

aly,

201

4]

Anan

d [U

S (C

alifo

rnia

), 20

13]

SALS

US

[UK

(Sco

tlan

d), 2

013-

2014

]

Fotio

u [G

reec

e, 2

014]

Arra

zola

[US

NYT

S, 2

014]

Alas

ka [U

S (A

lask

a), 2

015]

Reid

[Can

ada,

201

3]

Port

er [U

S (F

lorid

a), 2

014]

Gallu

s [It

aly,

201

3]

Babi

neau

[Ire

land

, 201

4]

Gallu

s [It

aly,

201

5]

East

woo

d [U

K (E

ngla

nd),

2014

]

Li [N

ew Z

eala

nd, 2

014]

John

ston

[US,

201

4]

Arra

zola

[US

NYT

S, 2

014]

Smok

ing

[UK

(Eng

land

), 20

14]

Suris

[Sw

itzer

land

, 201

5]

Smok

ing

[UK

(Eng

land

), 20

15]

Goni

ewic

z [P

olan

d, 2

013-

2014

]

Arra

zola

[US

NYT

S, 2

013]

Barn

ett [

US

(Flo

rida)

, 201

3]

Hun

gary

[Hun

gary

, 201

3]

East

woo

d [U

K (E

ngla

nd),

2013

]

Mon

tana

[US

(Mon

tana

), 20

15]

Port

er [U

S (F

lorid

a), 2

014]

Arra

zola

[US

NYT

S, 2

013]

Sour

ce

11-1

6

16-1

9

15-1

8

13-1

5

15 11-1

4

14-1

8

15-1

9

Age

11-1

4

16-1

9

16-1

7

16-1

9

11-1

8

15-1

7

13-1

8

15-1

8

16-2

0

16 16-2

0

15-1

9

11-1

4

11-1

8

13-1

5

14-1

8

15-1

8

15-1

8

rang

e

125

1205

276

7 406

251

431

Out

com

e

1479

3 26 2350 5782

1536

49 149

69589

89492

362

16 1323

3555

459

(n)

9022

153

2769

3205

1

1320

1041

9

1418

1658

6

Num

ber o

f

3697

9

163

821

160

2068

99 4160

0

1145

9

1405

621

1332

1970

8111

1261

5

4018

2177

4486

3292

1

1019

0

part

icip

ants

5.5

(3.5

, 7.9

)

1.4

(1.2

, 1.6

)

0.7

(0.0

, 3.6

)

7.4

(6.5

, 8.4

)

0.9

(0.8

, 1.0

)

0.5

(0.2

, 1.1

)

3.9

(3.5

, 4.3

)

17.7

(15.

7, 1

9.8)

2.6

(2.4

, 2.9

)

4.0

(3.8

, 4.2

)

1.8

(0.4

, 5.3

)

3.2

(2.1

, 4.6

)

1.3

(0.2

, 4.4

)

1.7

(1.2

, 2.3

)

0.0

(0.0

, 3.7

)

13.9

(13.

6, 1

4.2)

13.4

(12.

8, 1

4.0)

3.5

(2.6

, 4.6

)

24.0

(20.

7, 2

7.6)

5.2

(4.1

, 6.5

)

29.9

(27.

9, 3

2.0)

1.1

(0.9

, 1.3

)

3.9

(3.6

, 4.3

)

9.0

(8.1

, 9.9

)

0.7

(0.4

, 1.2

)

29.5

(28.

2, 3

0.9)

10.8

(10.

5, 1

1.1)

4.5

(4.1

, 4.9

)

ES (9

5% C

I)

100.

00

3.77

3.42

3.76

3.78

3.74

3.77

3.74

3.78

% 3.78

3.44

3.71

3.44

3.75

3.26

3.78

3.78

3.74

3.69

3.74

3.75

3.77

3.78

3.77

3.75

3.77

3.78

3.77

Wei

ght

5.5

(3.5

, 7.9

)

1.4

(1.2

, 1.6

)

0.7

(0.0

, 3.6

)

7.4

(6.5

, 8.4

)

0.9

(0.8

, 1.0

)

0.5

(0.2

, 1.1

)

3.9

(3.5

, 4.3

)

17.7

(15.

7, 1

9.8)

2.6

(2.4

, 2.9

)

4.0

(3.8

, 4.2

)

1.8

(0.4

, 5.3

)

3.2

(2.1

, 4.6

)

1.3

(0.2

, 4.4

)

1.7

(1.2

, 2.3

)

0.0

(0.0

, 3.7

)

13.9

(13.

6, 1

4.2)

13.4

(12.

8, 1

4.0)

3.5

(2.6

, 4.6

)

24.0

(20.

7, 2

7.6)

5.2

(4.1

, 6.5

)

29.9

(27.

9, 3

2.0)

1.1

(0.9

, 1.3

)

3.9

(3.6

, 4.3

)

9.0

(8.1

, 9.9

)

0.7

(0.4

, 1.2

)

29.5

(28.

2, 3

0.9)

10.8

(10.

5, 1

1.1)

4.5

(4.1

, 4.9

)

ES (9

5% C

I)

100.

00

3.77

3.42

3.76

3.78

3.74

3.77

3.74

3.78

% 3.78

3.44

3.71

3.44

3.75

3.26

3.78

3.78

3.74

3.69

3.74

3.75

3.77

3.78

3.77

3.75

3.77

3.78

3.77

Wei

ght

010

2030

4060

80


Figu

re 1

1: P

oole

d an

alys

is o

f eve

r e-c

igar

ette

use

am

ong

non-

smok

ing

yout

h fr

om 2

013-

2015


Author

Wang

Corey

Greece

Gallus

Babineau

Arrazola

Fotiou

Anand

Johnston

Gallus

Corey

Gallus

Subtotal (I^2 = 0.0%, p = 0.7)

Hungary

UK

Goniewicz

Reid

Porter

Poland

Italy

MooreSALSUS

Porter

Arrazola

Li

Hungary

ArrazolaPorter

Subtotal (I^2 = 100.0%, p = 0.0)

Korea

Corey

China (Hong Kong)

Canada

Ireland

Subtotal (I^2 = 0.0%, p = 0.4)

Arrazola

Porter

Montana

Porter

CoreyPorter

Alaska

Barnett

New Zealand

Lee

US

Subtotal (I^2 = 99.9%, p = 0.0)

Goniewicz

Hungary

Subtotal (I^2 = 100.0%, p = 0.0)

Country

China (Hong Kong)

US NYTS

Italy

Ireland

US NYTS

Greece

US (California)

US

Italy

US NYTS

Italy

Poland

Canada

US (Florida)

UK (Wales)UK (Scotland)

US (Florida)

US NYTS

New Zealand

Hungary

US NYTSUS (Florida)

US NYTS

US NYTS

US (Florida)

US (Montana)

US (Florida)

US NYTSUS (Florida)

US (Alaska)

US (Florida)

Korea

Poland

Hungary

collection

2012-2013

2012

Data

2015

2014

2013

2014

2013

2014

2013

2012

2014

2010-2011

2013

2011

20142013-2014

2012

2014

2014

2012

20142014

2011

2013

2012

2015

2014

20112011

2015

2013

2011

2013-2014

2013

range

12-18

15-18

Age

16-19

16-17

15-18

15

15-18

13-18

16-19

11-14

16-19

15-24

15-19

15-18

11-1613-15

15-18

11-14

15-17

13-15

15-1815-18

15-18

11-14

11-14

14-18

11-14

11-1411-14

14-18

11-18

13-18

15-19

13-15

N

45128

12899

160

821

10190

1320

2769

41600

163

11667

153

13787

16586

6163

902232051

36439

10419

99

2325

1145932921

9720

8111

36989

4486

36979

88806045

1418

12615

75643

1970

4018

(n)

496

361

Outcome

2

26

459

7

205

5782

3

128

1

1131

431

191

125276

1275

406

0

302

15363555

146

89

666

1323

1479

5391

251

492

3555

589

362

4.6 (3.2, 6.2)

ES (95% CI)

1.1 (1.0, 1.2)

2.8 (2.5, 3.1)

1.3 (0.2, 4.4)

3.2 (2.1, 4.6)

4.5 (4.1, 4.9)

0.5 (0.2, 1.1)

7.4 (6.5, 8.4)

13.9 (13.6, 14.2)

1.8 (0.4, 5.3)

1.1 (0.9, 1.3)

0.7 (0.0, 3.6)

1.2 (0.3, 2.5)

8.2 (7.8, 8.7)

2.6 (2.4, 2.9)

3.1 (2.7, 3.6)

1.4 (1.2, 1.6)0.9 (0.8, 1.0)

3.5 (3.3, 3.7)

3.9 (3.5, 4.3)

0.0 (0.0, 3.7)

13.0 (11.6, 14.4)

13.4 (12.8, 14.0)10.8 (10.5, 11.1)

10.4 (9.7, 11.2)

1.5 (1.3, 1.8)

1.0 (0.9, 1.1)

1.1 (0.9, 1.3)

1.8 (1.7, 1.9)

29.5 (28.2, 30.9)

4.0 (3.8, 4.2)

0.6 (0.4, 0.8)1.5 (1.2, 1.8)

17.7 (15.7, 19.8)

3.9 (3.6, 4.3)

4.7 (4.5, 4.9)

5.2 (3.2, 7.7)

29.9 (27.9, 32.0)

9.0 (8.1, 9.9)

10.3 (9.8, 10.8)

4.6 (3.2, 6.2)

ES (95% CI)

1.1 (1.0, 1.2)

2.8 (2.5, 3.1)

1.3 (0.2, 4.4)

3.2 (2.1, 4.6)

4.5 (4.1, 4.9)

0.5 (0.2, 1.1)

7.4 (6.5, 8.4)

13.9 (13.6, 14.2)

1.8 (0.4, 5.3)

1.1 (0.9, 1.3)

0.7 (0.0, 3.6)

1.2 (0.3, 2.5)

8.2 (7.8, 8.7)

2.6 (2.4, 2.9)

3.1 (2.7, 3.6)

1.4 (1.2, 1.6)0.9 (0.8, 1.0)

3.5 (3.3, 3.7)

3.9 (3.5, 4.3)

0.0 (0.0, 3.7)

13.0 (11.6, 14.4)

13.4 (12.8, 14.0)10.8 (10.5, 11.1)

10.4 (9.7, 11.2)

1.5 (1.3, 1.8)

1.0 (0.9, 1.1)

1.1 (0.9, 1.3)

1.8 (1.7, 1.9)

29.5 (28.2, 30.9)

4.0 (3.8, 4.2)

0.6 (0.4, 0.8)1.5 (1.2, 1.8)

17.7 (15.7, 19.8)

3.9 (3.6, 4.3)

4.7 (4.5, 4.9)

5.2 (3.2, 7.7)

29.9 (27.9, 32.0)

9.0 (8.1, 9.9)

10.3 (9.8, 10.8)

0 10 20 30 40

Figure 10: Pooled analysis of current e-cigarette use among youth by country (2008-2015)



Figu

re 1

1: P

oole

d an

alys

is o

f eve

r e-c

igar

ette

use

am

ong

non-

smok

ing

yout

h fr

om 2

013-

2015

Ove

rall

(I^2

= 9

9.2%

, p =

0.0

)

Moo

re

Ham

ilton

Barn

ett

Reid

SALS

US

Moo

re

Babi

neau

Kris

tjans

son

Gallu

s

Fotio

u

Whi

te

Gallu

s

Auth

or

Gallu

s

UK

(Wal

es)

Cana

da (O

ntar

io)

US

(Flo

rida)

Cana

da

UK

(Sco

tlan

d)

UK

(Wal

es)

Irel

and

Icel

and

Ital

y

Gree

ce

New

Zea

land

Ital

y

Coun

try

Ital

y

2014

2015

2013

Dat

a

2013

2013

-201

4

2014

2014

2015

2015

2014

2014

2013

colle

ctio

n

2014

11-1

6

14-1

8

11-1

8

Age

15-1

9

13-1

5

10-1

1

16-1

7

16-1

9

14-1

5

16-1

9

rang

e

16-1

9

8564

2448

1171

9

3814

0

2950

8

1581

670

2963

141

1076

2544

136

N 139

637

153

492

Out

com

e

5187

2222

8181 270

291 356

7(n)

1

7.0

(5.1

, 9.3

)

7.4

(6.9

, 8.0

)

6.3

(5.3

, 7.3

)

4.2

(3.8

, 4.6

)

13.6

(13.

3, 1

3.9)

7.5

(7.2

, 7.8

)

5.1

(4.1

, 6.3

)

12.1

(9.7

, 14.

8)

9.1

(8.1

, 10.

2)

1.4

(0.2

, 5.0

)

8.5

(6.9

, 10.

3)

14.0

(12.

7, 1

5.4)

5.1

(2.1

, 10.

3)

ES (9

5% C

I)

0.7

(0.0

, 3.9

)

7.0

(5.1

, 9.3

)

7.4

(6.9

, 8.0

)

6.3

(5.3

, 7.3

)

4.2

(3.8

, 4.6

)

13.6

(13.

3, 1

3.9)

7.5

(7.2

, 7.8

)

5.1

(4.1

, 6.3

)

12.1

(9.7

, 14.

8)

9.1

(8.1

, 10.

2)

1.4

(0.2

, 5.0

)

8.5

(6.9

, 10.

3)

14.0

(12.

7, 1

5.4)

5.1

(2.1

, 10.

3)

ES (9

5% C

I)

0.7

(0.0

, 3.9

)

05

1015

20


Figu

re 1

3: P

oole

d an

alys

is o

f eve

r e-c

igar

ette

use

am

ong

non-

smok

ing

yout

h by

cou

ntry

(200

8-20

15)

Figu

re 1

2: S

ensi

tivity

ana

lysi

s of

eve

r e-c

igar

ette

use

am

ong

non-

smok

ing

yout

h fr

om 2

013-

2015

Ove

rall

(I^2

= 9

9.2%

, p =

0.0

)

Ham

ilton

[Can

ada

(Ont

ario

), 20

15]

Sour

ce

Barn

ett [

US

(Flo

rida)

, 201

3]

Kris

tjans

son

[Icel

and,

201

5]

Gallu

s [It

aly,

201

4]

East

woo

d [U

K (E

ngla

nd),

2014

]

Moo

re [U

K (W

ales

), 20

14]

Whi

te [N

ew Z

eala

nd, 2

014]

Fotio

u [G

reec

e, 2

014]

Moo

re [U

K (W

ales

), 20

14]

Reid

[Can

ada,

201

3]

Gallu

s [It

aly,

201

5]

Babi

neau

[Ire

land

, 201

4]

East

woo

d [U

K (E

ngla

nd),

2013

]

Gallu

s [It

aly,

201

3]

SALS

US

[UK

(Sco

tlan

d), 2

013-

2014

]

14-1

8

rang

e

11-1

8

16-1

9

11-1

6

Age

14-1

5

10-1

1

15-1

9

16-1

9

16-1

7

16-1

9

13-1

5

153

(n)

492

270

1 83 637

Out

com

e

356

91 815187

281347 2222

2448

part

icip

ants

1171

9

2963

139

1790

8564

Num

ber o

f

2544

1076

1581

3814

0

141

670

1888

136

2950

8

6.4

(4.6

, 8.5

)

6.3

(5.3

, 7.3

)

ES (9

5% C

I)

4.2

(3.8

, 4.6

)

9.1

(8.1

, 10.

2)

0.7

(0.0

, 3.9

)

4.6

(3.7

, 5.7

)

7.4

(6.9

, 8.0

)

14.0

(12.

7, 1

5.4)

8.5

(6.9

, 10.

3)

5.1

(4.1

, 6.3

)

13.6

(13.

3, 1

3.9)

1.4

(0.2

, 5.0

)

12.1

(9.7

, 14.

8)

1.8

(1.3

, 2.5

)

5.1

(2.1

, 10.

3)

7.5

(7.2

, 7.8

)

100.

00

6.99

Wei

ght

7.09

7.01

5.43

6.95

7.08

% 7.00

6.84

6.93

7.11

5.45

6.68

6.96

5.40

7.10

6.4

(4.6

, 8.5

)

6.3

(5.3

, 7.3

)

ES (9

5% C

I)

4.2

(3.8

, 4.6

)

9.1

(8.1

, 10.

2)

0.7

(0.0

, 3.9

)

4.6

(3.7

, 5.7

)

7.4

(6.9

, 8.0

)

14.0

(12.

7, 1

5.4)

8.5

(6.9

, 10.

3)

5.1

(4.1

, 6.3

)

13.6

(13.

3, 1

3.9)

1.4

(0.2

, 5.0

)

12.1

(9.7

, 14.

8)

1.8

(1.3

, 2.5

)

5.1

(2.1

, 10.

3)

7.5

(7.2

, 7.8

)

100.

00

6.99

Wei

ght

7.09

7.01

5.43

6.95

7.08

% 7.00

6.84

6.93

7.11

5.45

6.68

6.96

5.40

7.10

010

2030

4060

80



Figu

re 1

3: P

oole

d an

alys

is o

f eve

r e-c

igar

ette

use

am

ong

non-

smok

ing

yout

h by

cou

ntry

(200

8-20

15)

Het

erog

enei

ty b

etw

een

grou

ps: p

= 0

.000

Ove

rall

(I^2

= 9

9.6%

, p =

0.0

);

Subt

otal

(I^

2 =

63.1

%, p

= 0

.1)

Cho

Kris

tjans

son

Fotio

u

Ham

ilton

Moo

re

Ital

y

SALS

US

Whi

te

Gallu

s

Subt

otal

(I^

2 =

86.2

%, p

= 0

.0)

Gree

ce

Icel

and

Goni

ewic

z

Auth

or

Cana

da (O

ntar

io)

Babi

neau

Gallu

s

Pola

nd

UK

Barn

ett

Kore

a

Reid

New

Zea

land

Dut

ra

US

Irel

and

Dut

ra

Moo

re

Cana

da

Gallu

s

Subt

otal

(I^

2 =

99.2

%, p

= 0

.0)

Kore

a

Icel

and

Gree

ce

Cana

da (O

ntar

io)

UK

(Wal

es)

UK

(Sco

tlan

d)

New

Zea

land

Ital

y

Pola

nd

Coun

try

Irel

and

Ital

y

US

(Flo

rida)

Cana

da

US

NYT

SU

S N

YTS

UK

(Wal

es)

Ital

y

2008

Dat

a

2015

2014

2015

2014

2013

-201

4

2014

2013

2010

-201

1

colle

ctio

n

2014

2015

2013

2013

2012

2011

2014

2014

13-1

9

Age

14-1

8

10-1

113

-15

14-1

5

16-1

9

15-2

4

rang

e

16-1

7

16-1

9

11-1

8

15-1

9

11-1

811

-18

11-1

6

16-1

9

3402

2963

1076

2448

1581

2950

8

2544

136

9022

N 670

141

1171

9

3814

0

2166

016

575

8564

139

5Out

com

e

270

91 153

812222

356

7785

(n)

812492

5187

945

292

637

1

5.8

(3.8

, 8.1

)

2.1

(0.3

, 5.1

)

0.1

(0.0

, 0.3

)

9.1

(8.1

, 10.

2)

8.5

(6.9

, 10.

3)

6.3

(5.3

, 7.3

)

5.1

(4.1

, 6.3

)7.

5 (7

.2, 7

.8)

14.0

(12.

7, 1

5.4)

5.1

(2.1

, 10.

3)

6.9

(6.0

, 7.8

)

8.7

(8.1

, 9.3

)

ES (9

5% C

I)

12.1

(9.7

, 14.

8)

1.4

(0.2

, 5.0

)

4.2

(3.8

, 4.6

)

13.6

(13.

3, 1

3.9)

4.4

(4.1

, 4.6

)1.

8 (1

.6, 2

.0)

7.4

(6.9

, 8.0

)

0.7

(0.0

, 3.9

)

3.3

(1.8

, 5.4

)

5.8

(3.8

, 8.1

)

2.1

(0.3

, 5.1

)

0.1

(0.0

, 0.3

)

9.1

(8.1

, 10.

2)

8.5

(6.9

, 10.

3)

6.3

(5.3

, 7.3

)

5.1

(4.1

, 6.3

)7.

5 (7

.2, 7

.8)

14.0

(12.

7, 1

5.4)

5.1

(2.1

, 10.

3)

6.9

(6.0

, 7.8

)

8.7

(8.1

, 9.3

)

ES (9

5% C

I)

12.1

(9.7

, 14.

8)

1.4

(0.2

, 5.0

)

4.2

(3.8

, 4.6

)

13.6

(13.

3, 1

3.9)

4.4

(4.1

, 4.6

)1.

8 (1

.6, 2

.0)

7.4

(6.9

, 8.0

)

0.7

(0.0

, 3.9

)

3.3

(1.8

, 5.4

)

05

1015

20


Figu

re 1

5: S

ensi

tivity

ana

lysi

s of

cur

rent

e-c

igar

ette

use

am

ong

non-

smok

ing

yout

h fr

om 2

013-

2015

Figu

re 1

4: P

oole

d an

alys

is o

f cur

rent

e-c

igar

ette

use

am

ong

non-

smok

ing

yout

h fr

om 2

013-

2015

Ove

rall

(I^2

= 9

9.9%

, p =

0.0

)

Moo

re

Gallu

s

Port

er

Auth

or

Barn

ett

Port

er

Gallu

s

Goni

ewic

z

Fotio

u

SALS

US

Gallu

s

Babi

neau

UK

(Wal

es)

Ital

y

US

(Flo

rida)

Coun

try

US

(Flo

rida)

US

(Flo

rida)

Ital

y

Pola

nd

Gree

ce

UK

(Sco

tlan

d)

Ital

y

Irel

and

2014

2015

2014

Dat

a

colle

ctio

n

2013

2014

2013

2013

-201

4

2014

2013

-201

4

2014

2014

11-1

6

16-1

9

15-1

8

Age

rang

e

11-1

8

11-1

4

16-1

9

15-1

9

13-1

5

16-1

9

16-1

7

8564

141

3006

5

N 1171

9

3592

0

136

1221

1076

2950

8

139

670

54 02074

Out

com

e

(n)

2227

1006

0 159

224 010

2.2

(0.3

, 5.6

)

0.6

(0.5

, 0.8

)

0.0

(0.0

, 2.6

)

6.9

(6.6

, 7.2

)

ES (9

5% C

I)

19.0

(18.

3, 1

9.7)

2.8

(2.6

, 3.0

)

0.0

(0.0

, 2.7

)

13.0

(11.

2, 1

5.0)

0.2

(0.0

, 0.7

)

0.1

(0.1

, 0.1

)

0.0

(0.0

, 2.6

)

1.5

(0.7

, 2.7

)

2.2

(0.3

, 5.6

)

0.6

(0.5

, 0.8

)

0.0

(0.0

, 2.6

)

6.9

(6.6

, 7.2

)

ES (9

5% C

I)

19.0

(18.

3, 1

9.7)

2.8

(2.6

, 3.0

)

0.0

(0.0

, 2.7

)

13.0

(11.

2, 1

5.0)

0.2

(0.0

, 0.7

)

0.1

(0.1

, 0.1

)

0.0

(0.0

, 2.6

)

1.5

(0.7

, 2.7

)

010

20



Figu

re 1

5: S

ensi

tivity

ana

lysi

s of

cur

rent

e-c

igar

ette

use

am

ong

non-

smok

ing

yout

h fr

om 2

013-

2015

Ove

rall

(I^2

= 9

9.6%

, p =

0.0

)

Babi

neau

[Ire

land

, 201

4]

Smok

ing

[UK

(Eng

land

), 20

14]

Gallu

s [It

aly,

201

3]

Port

er [U

S (F

lorid

a), 2

014]

Smok

ing

[UK

(Eng

land

), 20

15]

Fotio

u [G

reec

e, 2

014]

Goni

ewic

z [P

olan

d, 2

013-

2014

]

Barn

ett [

US

(Flo

rida)

, 201

3]

East

woo

d [U

K (E

ngla

nd),

2013

]

Moo

re [U

K (W

ales

), 20

14]

Gallu

s [It

aly,

201

5]

SALS

US

[UK

(Sco

tlan

d), 2

013-

2014

]

Sour

ce

Gallu

s [It

aly,

201

4]

Port

er [U

S (F

lorid

a), 2

014]

East

woo

d [U

K (E

ngla

nd),

2014

]

16-1

7

16-2

0

16-1

9

11-1

4

16-2

0

15-1

9

Age

11-1

8

11-1

6

16-1

9

13-1

5

rang

e

16-1

9

15-1

8

10 60 1006

132159

Out

com

e

316

5 54 024(n)

0 2074

26

670

1128

136

3592

0

1040

1076

1221

Num

ber o

f

1171

9

1888

8564

141

2950

8

part

icip

ants

139

3006

5

1790

1.3

(0.4

, 2.8

)

1.5

(0.7

, 2.7

)

0.5

(0.2

, 1.2

)

0.0

(0.0

, 2.7

)

2.8

(2.6

, 3.0

)

1.3

(0.7

, 2.1

)

0.2

(0.0

, 0.7

)

13.0

(11.

2, 1

5.0)

2.7

(2.4

, 3.0

)

0.3

(0.1

, 0.6

)

0.6

(0.5

, 0.8

)

0.0

(0.0

, 2.6

)

0.1

(0.1

, 0.1

)

ES (9

5% C

I)

0.0

(0.0

, 2.6

)

6.9

(6.6

, 7.2

)

1.5

(1.0

, 2.1

)

100.

00

6.70

6.80

5.88

6.95

6.79

6.79

6.81

% 6.94

6.86

6.93

5.91

6.94

Wei

ght

5.90

6.94

6.86

1.3

(0.4

, 2.8

)

1.5

(0.7

, 2.7

)

0.5

(0.2

, 1.2

)

0.0

(0.0

, 2.7

)

2.8

(2.6

, 3.0

)

1.3

(0.7

, 2.1

)

0.2

(0.0

, 0.7

)

13.0

(11.

2, 1

5.0)

2.7

(2.4

, 3.0

)

0.3

(0.1

, 0.6

)

0.6

(0.5

, 0.8

)

0.0

(0.0

, 2.6

)

0.1

(0.1

, 0.1

)

ES (9

5% C

I)

0.0

(0.0

, 2.6

)

6.9

(6.6

, 7.2

)

1.5

(1.0

, 2.1

)

100.

00

6.70

6.80

5.88

6.95

6.79

6.79

6.81

% 6.94

6.86

6.93

5.91

6.94

Wei

ght

5.90

6.94

6.86

010

2030

4060

80


Figu

re 1

7: P

oole

d an

alys

is o

f eve

r e-c

igar

ette

use

am

ong

smok

ing

yout

h fr

om 2

013-

2015

Figu

re 1

6: P

oole

d an

alys

is o

f cur

rent

e-c

igar

ette

use

am

ong

non-

smok

ing

yout

h by

cou

ntry

(201

0-20

15)

Het

erog

enei

ty b

etw

een

grou

ps: p

= 0

.000

Ove

rall

(I^2

= 9

9.8%

, p =

0.0

);

Hun

gary

Goni

ewic

z

Subt

otal

(I^

2 =

0.0%

, p =

1.0

)

US

SALS

US

Gree

ce

Hun

gary

Barn

ett

Ital

yGa

llus

Subt

otal

(I^

2 =

99.9

%, p

= 0

.0)

Subt

otal

(I^

2 =

100.

0%, p

= 0

.0)

Port

er

Kore

a

Gallu

s

Lee

Wan

g

Port

er

UK

Dut

ra

Moo

re

Babi

neau

Fotio

u

Dut

ra

Goni

ewic

z

Irel

and

Subt

otal

(I^

2 =

0.0%

, p =

1.0

)

Port

er

Auth

or

Gallu

s

Chin

a (H

ong

Kong

)

Port

er

Pola

nd

Hun

gary

Pola

nd

UK

(Sco

tlan

d)

US

(Flo

rida)

Ital

y

US

(Flo

rida)

Ital

y

Kore

a

Chin

a (H

ong

Kong

)

US

(Flo

rida)

US

NYT

S

UK

(Wal

es)

Irel

and

Gree

ce

US

NYT

S

Pola

nd

US

(Flo

rida)

Coun

try

Ital

y

US

(Flo

rida)

2012

2013

-201

4

2013

-201

4

2013

Dat

a

2013

2011

2014

2011

2012

-201

3

2014

2011

2014

2014

2014

2012

2010

-201

1

2014

colle

ctio

n

2015

2011

13-1

5

15-1

9

13-1

5

11-1

8

Age

16-1

9

11-1

4

16-1

9

13-1

8

12-1

8

11-1

4

11-1

8

11-1

6

16-1

7

11-1

8

15-2

4

15-1

8

rang

e

16-1

9

15-1

8

1697

1221

2950

8

1171

9

136

5791

139

6498

3

4017

9

3592

0

1657

5

8564

670

1076

2166

0

9022

3006

5

N 141

5362

80159

242227

Out

com

e

041 03698

221

1006

98 54 102232

217

2074

(n)

043

2.0

(0.8

, 3.7

)

4.7

(3.8

, 5.8

)

13.0

(11.

2, 1

5.0)

0.2

(0.1

, 0.2

)

0.1

(0.1

, 0.1

)

19.0

(18.

3, 1

9.7)

0.0

(0.0

, 2.7

)

3.1

(0.8

, 6.9

)

3.2

(2.9

, 3.6

)

0.7

(0.5

, 1.0

)

0.0

(0.0

, 2.6

)

5.7

(5.5

, 5.9

)

0.6

(0.5

, 0.6

)

2.8

(2.6

, 3.0

)

0.6

(0.5

, 0.7

)

0.6

(0.5

, 0.8

)

1.5

(0.7

, 2.7

)

0.2

(0.0

, 0.7

)

1.1

(0.9

, 1.2

)

2.4

(2.1

, 2.7

)

0.0

(0.0

, 0.5

)

6.9

(6.6

, 7.2

)

ES (9

5% C

I)

0.0

(0.0

, 2.6

)

0.8

(0.6

, 1.1

)

2.0

(0.8

, 3.7

)

4.7

(3.8

, 5.8

)

13.0

(11.

2, 1

5.0)

0.2

(0.1

, 0.2

)

0.1

(0.1

, 0.1

)

19.0

(18.

3, 1

9.7)

0.0

(0.0

, 2.7

)

3.1

(0.8

, 6.9

)

3.2

(2.9

, 3.6

)

0.7

(0.5

, 1.0

)

0.0

(0.0

, 2.6

)

5.7

(5.5

, 5.9

)

0.6

(0.5

, 0.6

)

2.8

(2.6

, 3.0

)

0.6

(0.5

, 0.7

)

0.6

(0.5

, 0.8

)

1.5

(0.7

, 2.7

)

0.2

(0.0

, 0.7

)

1.1

(0.9

, 1.2

)

2.4

(2.1

, 2.7

)

0.0

(0.0

, 0.5

)

6.9

(6.6

, 7.2

)

ES (9

5% C

I)

0.0

(0.0

, 2.6

)

0.8

(0.6

, 1.1

)

010

20



Figu

re 1

7: P

oole

d an

alys

is o

f eve

r e-c

igar

ette

use

am

ong

smok

ing

yout

h fr

om 2

013-

2015

Het

erog

enei

ty b

etw

een

grou

ps: p

= 0

.000

Ove

rall

(I^2

= 9

9.8%

, p =

0.0

);

Hun

gary

Goni

ewic

z

Subt

otal

(I^

2 =

0.0%

, p =

1.0

)

US

SALS

US

Gree

ce

Hun

gary

Barn

ett

Ital

yGa

llus

Subt

otal

(I^

2 =

99.9

%, p

= 0

.0)

Subt

otal

(I^

2 =

100.

0%, p

= 0

.0)

Port

er

Kore

a

Gallu

s

Lee

Wan

g

Port

er

UK

Dut

ra

Moo

re

Babi

neau

Fotio

u

Dut

ra

Goni

ewic

z

Irel

and

Subt

otal

(I^

2 =

0.0%

, p =

1.0

)

Port

er

Auth

or

Gallu

s

Chin

a (H

ong

Kong

)

Port

er

Pola

nd

Hun

gary

Pola

nd

UK

(Sco

tlan

d)

US

(Flo

rida)

Ital

y

US

(Flo

rida)

Ital

y

Kore

a

Chin

a (H

ong

Kong

)

US

(Flo

rida)

US

NYT

S

UK

(Wal

es)

Irel

and

Gree

ce

US

NYT

S

Pola

nd

US

(Flo

rida)

Coun

try

Ital

y

US

(Flo

rida)

2012

2013

-201

4

2013

-201

4

2013

Dat

a

2013

2011

2014

2011

2012

-201

3

2014

2011

2014

2014

2014

2012

2010

-201

1

2014

colle

ctio

n

2015

2011

13-1

5

15-1

9

13-1

5

11-1

8

Age

16-1

9

11-1

4

16-1

9

13-1

8

12-1

8

11-1

4

11-1

8

11-1

6

16-1

7

11-1

8

15-2

4

15-1

8

rang

e

16-1

9

15-1

8

1697

1221

2950

8

1171

9

136

5791

139

6498

3

4017

9

3592

0

1657

5

8564

670

1076

2166

0

9022

3006

5

N 141

5362

80159

242227

Out

com

e

041 03698

221

1006

98 54 102232

217

2074

(n)

043

2.0

(0.8

, 3.7

)

4.7

(3.8

, 5.8

)

13.0

(11.

2, 1

5.0)

0.2

(0.1

, 0.2

)

0.1

(0.1

, 0.1

)

19.0

(18.

3, 1

9.7)

0.0

(0.0

, 2.7

)

3.1

(0.8

, 6.9

)

3.2

(2.9

, 3.6

)

0.7

(0.5

, 1.0

)

0.0

(0.0

, 2.6

)

5.7

(5.5

, 5.9

)

0.6

(0.5

, 0.6

)

2.8

(2.6

, 3.0

)

0.6

(0.5

, 0.7

)

0.6

(0.5

, 0.8

)

1.5

(0.7

, 2.7

)

0.2

(0.0

, 0.7

)

1.1

(0.9

, 1.2

)

2.4

(2.1

, 2.7

)

0.0

(0.0

, 0.5

)

6.9

(6.6

, 7.2

)

ES (9

5% C

I)

0.0

(0.0

, 2.6

)

0.8

(0.6

, 1.1

)

2.0

(0.8

, 3.7

)

4.7

(3.8

, 5.8

)

13.0

(11.

2, 1

5.0)

0.2

(0.1

, 0.2

)

0.1

(0.1

, 0.1

)

19.0

(18.

3, 1

9.7)

0.0

(0.0

, 2.7

)

3.1

(0.8

, 6.9

)

3.2

(2.9

, 3.6

)

0.7

(0.5

, 1.0

)

0.0

(0.0

, 2.6

)

5.7

(5.5

, 5.9

)

0.6

(0.5

, 0.6

)

2.8

(2.6

, 3.0

)

0.6

(0.5

, 0.7

)

0.6

(0.5

, 0.8

)

1.5

(0.7

, 2.7

)

0.2

(0.0

, 0.7

)

1.1

(0.9

, 1.2

)

2.4

(2.1

, 2.7

)

0.0

(0.0

, 0.5

)

6.9

(6.6

, 7.2

)

ES (9

5% C

I)

0.0

(0.0

, 2.6

)

0.8

(0.6

, 1.1

)

010

20

Ove

rall

(I^2

= 9

7.9%

, p =

0.0

)

Gallu

s

Kris

tjans

son

Gallu

s

Moo

re

Ham

ilton

Auth

or

Whi

te

Fotio

u

Gallu

s

Babi

neau

Reid

Barn

ett

Moo

re

SALS

US

Ital

y

Icel

and

Ital

y

UK

(Wal

es)

Cana

da (O

ntar

io)

Coun

try

New

Zea

land

Gree

ce

Ital

y

Irel

and

Cana

da

US

(Flo

rida)

UK

(Wal

es)

UK

(Sco

tlan

d)

2015

2015

2014

2014

2015

colle

ctio

n

2014

2014

2013

2014

2013

2013

2014

2013

-201

4

Dat

a

16-1

9

16-1

9

11-1

6

14-1

8

rang

e

14-1

5

16-1

9

16-1

7

15-1

9

11-1

8

10-1

1

13-1

5

Age

19514

14 465

442

N 375

244

27 151

9063

896

122543

5317

5 246

253

(n)

228

128

8 896571

603

61265

Out

com

e

54.7

(47.

0, 6

2.3)

26.3

(9.1

, 51.

2)

61.7

(57.

3, 6

5.9)

35.7

(12.

8, 6

4.9)

52.9

(48.

3, 5

7.5)

57.2

(52.

5, 6

1.9)

ES (9

5% C

I)

60.8

(55.

7, 6

5.8)

52.5

(46.

0, 5

8.9)

29.6

(13.

8, 5

0.2)

58.9

(50.

7, 6

6.9)

72.5

(71.

6, 7

3.4)

67.3

(64.

1, 7

0.4)

50.0

(21.

1, 7

8.9)

49.7

(47.

8, 5

1.7)

54.7

(47.

0, 6

2.3)

26.3

(9.1

, 51.

2)

61.7

(57.

3, 6

5.9)

35.7

(12.

8, 6

4.9)

52.9

(48.

3, 5

7.5)

57.2

(52.

5, 6

1.9)

ES (9

5% C

I)

60.8

(55.

7, 6

5.8)

52.5

(46.

0, 5

8.9)

29.6

(13.

8, 5

0.2)

58.9

(50.

7, 6

6.9)

72.5

(71.

6, 7

3.4)

67.3

(64.

1, 7

0.4)

50.0

(21.

1, 7

8.9)

49.7

(47.

8, 5

1.7)

010

2030

4060

80


Figu

re 1

9: P

oole

d an

alys

is o

f eve

r e-c

igar

ette

use

am

ong

smok

ing

yout

h by

cou

ntry

(200

8-20

15)

Figu

re 1

8: S

ensi

tivity

ana

lysi

s of

eve

r e-c

igar

ette

use

am

ong

smok

ing

yout

h fr

om 2

013-

2015

Ove

rall

(I^2

= 9

7.8%

, p =

0.0

)

Sour

ce

Kris

tjans

son

[Icel

and,

201

5]

Gallu

s [It

aly,

201

3]

Moo

re [U

K (W

ales

), 20

14]

Fotio

u [G

reec

e, 2

014]

Gallu

s [It

aly,

201

4]

Moo

re [U

K (W

ales

), 20

14]

Ham

ilton

[Can

ada

(Ont

ario

), 20

15]

East

woo

d [U

K (E

ngla

nd),

2014

]

East

woo

d [U

K (E

ngla

nd),

2013

]

Babi

neau

[Ire

land

, 201

4]

SALS

US

[UK

(Sco

tlan

d), 2

013-

2014

]

Gallu

s [It

aly,

201

5]

Whi

te [N

ew Z

eala

nd, 2

014]

Barn

ett [

US

(Flo

rida)

, 201

3]

Reid

[Can

ada,

201

3]

rang

e

16-1

9

11-1

6

16-1

9

10-1

1

14-1

8

16-1

7

13-1

5

16-1

9

14-1

5

11-1

8

15-1

9

Age

(n)

317

8 246

128

5 6 253

7357 891265

5228

603

6571

Out

com

e

part

icip

ants

514

27 465

244

14 12 442

136

156

151

2543

19375

896

9063

Num

ber o

f

53.2

(45.

9, 6

0.5)

ES (9

5% C

I)

61.7

(57.

3, 6

5.9)

29.6

(13.

8, 5

0.2)

52.9

(48.

3, 5

7.5)

52.5

(46.

0, 5

8.9)

35.7

(12.

8, 6

4.9)

50.0

(21.

1, 7

8.9)

57.2

(52.

5, 6

1.9)

53.7

(44.

9, 6

2.3)

36.5

(29.

0, 4

4.6)

58.9

(50.

7, 6

6.9)

49.7

(47.

8, 5

1.7)

26.3

(9.1

, 51.

2)

60.8

(55.

7, 6

5.8)

67.3

(64.

1, 7

0.4)

72.5

(71.

6, 7

3.4)

100.

00

Wei

ght

7.65

5.14

7.63

7.43

3.92

3.63

7.62

7.11

7.20

7.18

7.82

4.50

7.57

7.74

7.86

%

53.2

(45.

9, 6

0.5)

ES (9

5% C

I)

61.7

(57.

3, 6

5.9)

29.6

(13.

8, 5

0.2)

52.9

(48.

3, 5

7.5)

52.5

(46.

0, 5

8.9)

35.7

(12.

8, 6

4.9)

50.0

(21.

1, 7

8.9)

57.2

(52.

5, 6

1.9)

53.7

(44.

9, 6

2.3)

36.5

(29.

0, 4

4.6)

58.9

(50.

7, 6

6.9)

49.7

(47.

8, 5

1.7)

26.3

(9.1

, 51.

2)

60.8

(55.

7, 6

5.8)

67.3

(64.

1, 7

0.4)

72.5

(71.

6, 7

3.4)

100.

00

Wei

ght

7.65

5.14

7.63

7.43

3.92

3.63

7.62

7.11

7.20

7.18

7.82

4.50

7.57

7.74

7.86

%

010

2030

4060

80



Figu

re 1

9: P

oole

d an

alys

is o

f eve

r e-c

igar

ette

use

am

ong

smok

ing

yout

h by

cou

ntry

(200

8-20

15)

Het

erog

enei

ty b

etw

een

grou

ps: p

= 0

.000

Ove

rall

(I^2

= 9

9.5%

, p =

0.0

);

Moo

re

Kore

a

SALS

US

Cana

da

US

Subt

otal

(I^

2 =

0.0%

, p =

0.8

)

New

Zea

land

Moo

re

Icel

and

Whi

te

Barn

ett

Ital

yGa

llus

Fotio

u

Auth

or

Gree

ce

Gallu

sGa

llus

Dut

ra

Pola

nd

Irel

and

Babi

neau

Reid

Subt

otal

(I^

2 =

99.3

%, p

= 0

.0)

Cho

Ham

ilton

Subt

otal

(I^

2 =

0.0%

, p =

0.5

)

Goni

ewic

z

Kris

tjans

son

UK

Dut

ra

Cana

da (O

ntar

io)

UK

(Wal

es)

UK

(Sco

tlan

d)

UK

(Wal

es)

New

Zea

land

US

(Flo

rida)

Ital

y

Gree

ce

Coun

try

Ital

yIt

aly

US

NYT

S

Irel

and

Cana

da

Kore

a

Cana

da (O

ntar

io)

Pola

nd

Icel

and

US

NYT

S

2014

2013

-201

4

2014

2014

Dat

a

2013

2013

2014

colle

ctio

n

2015

2014

2011

2014

2013

2008

2015

2010

-201

1

2015

2012

10-1

113

-15

11-1

6

14-1

5

Age

11-1

8

16-1

9

rang

e

16-1

916

-19

11-1

8

16-1

7

15-1

9

13-1

9

14-1

8

15-2

4

11-1

8

122543

465

375

896

27 244

N 1914778

151

9063

810

442

4738

514

869

61265

246

228

Out

com

e

603

8 128

(n)

55219

896571

16 253

2042

317

505

47.0

(36.

0, 5

8.1)

50.0

(21.

1, 7

8.9)

49.7

(47.

8, 5

1.7)

29.9

(18.

5, 4

2.5)

52.9

(48.

3, 5

7.5)

60.8

(55.

7, 6

5.8)

67.3

(64.

1, 7

0.4)

29.6

(13.

8, 5

0.2)

52.5

(46.

0, 5

8.9)

ES (9

5% C

I)

26.3

(9.1

, 51.

2)35

.7 (1

2.8,

64.

9)

28.1

(25.

0, 3

1.5)

58.9

(50.

7, 6

6.9)

72.5

(71.

6, 7

3.4)

51.1

(28.

4, 7

3.5)

2.0

(1.1

, 3.2

)

57.2

(52.

5, 6

1.9)

50.2

(48.

4, 5

2.1)

43.1

(41.

7, 4

4.5)

61.7

(57.

3, 6

5.9)

58.1

(54.

8, 6

1.4)

47.0

(36.

0, 5

8.1)

50.0

(21.

1, 7

8.9)

49.7

(47.

8, 5

1.7)

29.9

(18.

5, 4

2.5)

52.9

(48.

3, 5

7.5)

60.8

(55.

7, 6

5.8)

67.3

(64.

1, 7

0.4)

29.6

(13.

8, 5

0.2)

52.5

(46.

0, 5

8.9)

ES (9

5% C

I)

26.3

(9.1

, 51.

2)35

.7 (1

2.8,

64.

9)

28.1

(25.

0, 3

1.5)

58.9

(50.

7, 6

6.9)

72.5

(71.

6, 7

3.4)

51.1

(28.

4, 7

3.5)

2.0

(1.1

, 3.2

)

57.2

(52.

5, 6

1.9)

50.2

(48.

4, 5

2.1)

43.1

(41.

7, 4

4.5)

61.7

(57.

3, 6

5.9)

58.1

(54.

8, 6

1.4)

010

2030

4060

80


Figu

re 2

1: P

oole

d an

alys

is o

f cur

rent

e-c

igar

ette

use

am

ong

smok

ing

yout

h fr

om 2

013-

2015

Figu

re 2

0: P

oole

d an

alys

is o

f cur

rent

e-c

igar

ette

use

am

ong

smok

ing

yout

h fr

om 2

013-

2015

Ove

rall

(I^2

= 9

9.6%

, p =

0.0

)

SALS

US

Babi

neau

Gallu

s

Goni

ewic

z

Port

er

Moo

re

Port

er

Gallu

s

Fotio

u

Auth

or

Gallu

s

Barn

ett

UK

(Sco

tlan

d)

Irel

and

Ital

y

Pola

nd

US

(Flo

rida)

UK

(Wal

es)

US

(Flo

rida)

Ital

y

Gree

ce

Coun

try

Ital

y

US

(Flo

rida)

2013

-201

4

2014

2013

2013

-201

4

2014

2014

2014

2014

2014

colle

ctio

n

2015

2013

Dat

a

13-1

5

16-1

7

16-1

9

15-1

9

11-1

4

11-1

6

15-1

8

16-1

9

rang

e

16-1

9

11-1

8

Age

2543

151

27 749

1073

465

2865

14244

N 19896

252

163 430

481

71 1481

15(n)

124Out

com

e

17.2

(5.8

, 32.

6)

9.9

(8.8

, 11.

1)

10.6

(6.2

, 16.

6)

11.1

(2.4

, 29.

2)

57.4

(53.

8, 6

1.0)

44.8

(41.

8, 4

7.9)

15.3

(12.

1, 1

8.9)

51.7

(49.

8, 5

3.5)

7.1

(0.2

, 33.

9)

2.0

(0.7

, 4.7

)

ES (9

5% C

I)

5.3

(0.1

, 26.

0)

2.7

(1.7

, 4.0

)

17.2

(5.8

, 32.

6)

9.9

(8.8

, 11.

1)

10.6

(6.2

, 16.

6)

11.1

(2.4

, 29.

2)

57.4

(53.

8, 6

1.0)

44.8

(41.

8, 4

7.9)

15.3

(12.

1, 1

8.9)

51.7

(49.

8, 5

3.5)

7.1

(0.2

, 33.

9)

2.0

(0.7

, 4.7

)

ES (9

5% C

I)

5.3

(0.1

, 26.

0)

2.7

(1.7

, 4.0

)

010

2030

4060

80



Figu

re 2

1: P

oole

d an

alys

is o

f cur

rent

e-c

igar

ette

use

am

ong

smok

ing

yout

h fr

om 2

013-

2015

Ove

rall

(I^2

= 9

9.3%

, p =

0.0

)

Fotio

u [G

reec

e, 2

014]

Port

er [U

S (F

lorid

a), 2

014]

Smok

ing

[UK

(Eng

land

), 20

14]

Gallu

s [It

aly,

201

3]

Gallu

s [It

aly,

201

4]

Moo

re [U

K (W

ales

), 20

14]

SALS

US

[UK

(Sco

tlan

d), 2

013-

2014

]

East

woo

d [U

K (E

ngla

nd),

2014

]

Goni

ewic

z [P

olan

d, 2

013-

2014

]

Babi

neau

[Ire

land

, 201

4]

Sour

ce

Barn

ett [

US

(Flo

rida)

, 201

3]

Port

er [U

S (F

lorid

a), 2

014]

Smok

ing

[UK

(Eng

land

), 20

15]

East

woo

d [U

K (E

ngla

nd),

2013

]

Gallu

s [It

aly,

201

5]

11-1

4

16-2

0

16-1

9

16-1

9

11-1

6

13-1

5

15-1

9

16-1

7

rang

e

11-1

8

15-1

8

16-2

0

16-1

9

Age

5 481

433 1 71252

18430

16(n)

170

1481

5612 1Out

com

e

244

1073

277

27 14 465

2543

136

749

151

part

icip

ants

896

2865

292

156

19Num

ber o

f

17.8

(8.8

, 28.

9)

2.0

(0.7

, 4.7

)

44.8

(41.

8, 4

7.9)

15.5

(11.

5, 2

0.3)

11.1

(2.4

, 29.

2)

7.1

(0.2

, 33.

9)

15.3

(12.

1, 1

8.9)

9.9

(8.8

, 11.

1)

13.2

(8.0

, 20.

1)

57.4

(53.

8, 6

1.0)

10.6

(6.2

, 16.

6)

ES (9

5% C

I)

19.0

(16.

5, 2

1.7)

51.7

(49.

8, 5

3.5)

19.2

(14.

8, 2

4.2)

7.7

(4.0

, 13.

1)

5.3

(0.1

, 26.

0)

100.

00

6.86

6.95

6.87

6.09

5.47

6.91

6.96

6.78

6.94

6.79

Wei

ght

6.94

6.96

6.88

6.80

5.79

%

17.8

(8.8

, 28.

9)

2.0

(0.7

, 4.7

)

44.8

(41.

8, 4

7.9)

15.5

(11.

5, 2

0.3)

11.1

(2.4

, 29.

2)

7.1

(0.2

, 33.

9)

15.3

(12.

1, 1

8.9)

9.9

(8.8

, 11.

1)

13.2

(8.0

, 20.

1)

57.4

(53.

8, 6

1.0)

10.6

(6.2

, 16.

6)

ES (9

5% C

I)

19.0

(16.

5, 2

1.7)

51.7

(49.

8, 5

3.5)

19.2

(14.

8, 2

4.2)

7.7

(4.0

, 13.

1)

5.3

(0.1

, 26.

0)

100.

00

6.86

6.95

6.87

6.09

5.47

6.91

6.96

6.78

6.94

6.79

Wei

ght

6.94

6.96

6.88

6.80

5.79

%

010

2030

4060

80


Figu

re 2

3: P

oole

d ad

just

ed o

dds

ratio

for l

ongi

tudi

nal s

tudi

es a

sses

sing

ass

ocia

tion

of e

ver e

-cig

aret

te

use

amon

g no

n-sm

oker

s at

bas

elin

e w

ith to

bacc

o ci

gare

tte

upta

ke

Figu

re 2

2: P

oole

d an

alys

es o

f cur

rent

e-c

igar

ette

use

am

ong

smok

ing

yout

h by

cou

ntry

(201

0-20

15)

Het

erog

enei

ty b

etw

een

grou

ps: p

= 0

.000

Ove

rall

(I^2

= 9

9.7%

, p =

0.0

);

Gallu

s

Subt

otal

(I^

2 =

0.0%

, p =

0.6

)

Auth

or

Gallu

s

Kore

a

US

Barn

ett

Port

er

Irel

and

Pola

nd

Babi

neau

Goni

ewic

z

Gallu

s

SALS

US

Wan

g

Ital

y

Port

er

Goni

ewic

z

Port

er

Dut

ra

Gree

ce

Lee

Moo

re

Port

er

Subt

otal

(I^

2 =

0.0%

, p =

0.8

)

Chin

a (H

ong

Kong

)

Subt

otal

(I^

2 =

100.

0%, p

= 0

.0)

Subt

otal

(I^

2 =

99.6

%, p

= 0

.0)

Dut

ra

Fotio

u

UK

Ital

y

Coun

try

Ital

y

US

(Flo

rida)

US

(Flo

rida)

Irel

and

Pola

nd

Ital

y

UK

(Sco

tlan

d)

Chin

a (H

ong

Kong

)

US

(Flo

rida)

Pola

nd

US

(Flo

rida)

US

NYT

S

Kore

a

UK

(Wal

es)

US

(Flo

rida)

US

NYT

S

Gree

ce

2015

colle

ctio

n

2014

2013

Dat

a

2014

2014

2010

-201

1

2013

2013

-201

4

2012

-201

3

2011

2013

-201

4

2014

2012

2011

2014

2011

2011

2014

16-1

9

rang

e

16-1

9

11-1

8

Age

11-1

4

16-1

7

15-2

4

16-1

9

13-1

5

12-1

8

15-1

8

15-1

9

15-1

8

11-1

8

13-1

8

11-1

6

11-1

4

11-1

8

19N 14896

1073

151

4738

27 2543

4978

801

749

2865

869

7302

465

254

778

244

1(n)

124Out

com

e

481

16725

3 252

218

147

430

1481

230

2672

7148 76 5

17.4

(9.9

, 26.

4)

5.3

(0.1

, 26.

0)

10.6

(9.6

, 11.

8)

ES (9

5% C

I)

7.1

(0.2

, 33.

9)

2.7

(1.7

, 4.0

)44

.8 (4

1.8,

47.

9)

10.6

(6.2

, 16.

6)

15.3

(14.

3, 1

6.4)

11.1

(2.4

, 29.

2)

9.9

(8.8

, 11.

1)

4.4

(3.8

, 5.0

)

18.4

(15.

7, 2

1.2)

57.4

(53.

8, 6

1.0)

51.7

(49.

8, 5

3.5)

26.5

(23.

6, 2

9.5)

36.6

(35.

5, 3

7.7)

15.3

(12.

1, 1

8.9)

18.9

(14.

3, 2

4.3)

8.1

(1.8

, 17.

1)

20.0

(19.

0, 2

1.1)

22.4

(8.8

, 40.

0)

9.8

(7.8

, 12.

1)

2.0

(0.7

, 4.7

)

17.4

(9.9

, 26.

4)

5.3

(0.1

, 26.

0)

10.6

(9.6

, 11.

8)

ES (9

5% C

I)

7.1

(0.2

, 33.

9)

2.7

(1.7

, 4.0

)44

.8 (4

1.8,

47.

9)

10.6

(6.2

, 16.

6)

15.3

(14.

3, 1

6.4)

11.1

(2.4

, 29.

2)

9.9

(8.8

, 11.

1)

4.4

(3.8

, 5.0

)

18.4

(15.

7, 2

1.2)

57.4

(53.

8, 6

1.0)

51.7

(49.

8, 5

3.5)

26.5

(23.

6, 2

9.5)

36.6

(35.

5, 3

7.7)

15.3

(12.

1, 1

8.9)

18.9

(14.

3, 2

4.3)

8.1

(1.8

, 17.

1)

20.0

(19.

0, 2

1.1)

22.4

(8.8

, 40.

0)

9.8

(7.8

, 12.

1)

2.0

(0.7

, 4.7

)

010

2030

4060

80



Figu

re 2

3: P

oole

d ad

just

ed o

dds

ratio

for l

ongi

tudi

nal s

tudi

es a

sses

sing

ass

ocia

tion

of e

ver e

-cig

aret

te

use

amon

g no

n-sm

oker

s at

bas

elin

e w

ith to

bacc

o ci

gare

tte

upta

ke

Het

erog

enei

ty b

etw

een

grou

ps: p

= 0

.000

Ove

rall

(I^2

= 9

9.7%

, p =

0.0

);

Gallu

s

Subt

otal

(I^

2 =

0.0%

, p =

0.6

)

Auth

or

Gallu

s

Kore

a

US

Barn

ett

Port

er

Irel

and

Pola

nd

Babi

neau

Goni

ewic

z

Gallu

s

SALS

US

Wan

g

Ital

y

Port

er

Goni

ewic

z

Port

er

Dut

ra

Gree

ce

Lee

Moo

re

Port

er

Subt

otal

(I^

2 =

0.0%

, p =

0.8

)

Chin

a (H

ong

Kong

)

Subt

otal

(I^

2 =

100.

0%, p

= 0

.0)

Subt

otal

(I^

2 =

99.6

%, p

= 0

.0)

Dut

ra

Fotio

u

UK

Ital

y

Coun

try

Ital

y

US

(Flo

rida)

US

(Flo

rida)

Irel

and

Pola

nd

Ital

y

UK

(Sco

tlan

d)

Chin

a (H

ong

Kong

)

US

(Flo

rida)

Pola

nd

US

(Flo

rida)

US

NYT

S

Kore

a

UK

(Wal

es)

US

(Flo

rida)

US

NYT

S

Gree

ce

2015

colle

ctio

n

2014

2013

Dat

a

2014

2014

2010

-201

1

2013

2013

-201

4

2012

-201

3

2011

2013

-201

4

2014

2012

2011

2014

2011

2011

2014

16-1

9

rang

e

16-1

9

11-1

8

Age

11-1

4

16-1

7

15-2

4

16-1

9

13-1

5

12-1

8

15-1

8

15-1

9

15-1

8

11-1

8

13-1

8

11-1

6

11-1

4

11-1

8

19N 14896

1073

151

4738

27 2543

4978

801

749

2865

869

7302

465

254

778

244

1(n)

124Out

com

e

481

16725

3 252

218

147

430

1481

230

2672

7148 76 5

17.4

(9.9

, 26.

4)

5.3

(0.1

, 26.

0)

10.6

(9.6

, 11.

8)

ES (9

5% C

I)

7.1

(0.2

, 33.

9)

2.7

(1.7

, 4.0

)44

.8 (4

1.8,

47.

9)

10.6

(6.2

, 16.

6)

15.3

(14.

3, 1

6.4)

11.1

(2.4

, 29.

2)

9.9

(8.8

, 11.

1)

4.4

(3.8

, 5.0

)

18.4

(15.

7, 2

1.2)

57.4

(53.

8, 6

1.0)

51.7

(49.

8, 5

3.5)

26.5

(23.

6, 2

9.5)

36.6

(35.

5, 3

7.7)

15.3

(12.

1, 1

8.9)

18.9

(14.

3, 2

4.3)

8.1

(1.8

, 17.

1)

20.0

(19.

0, 2

1.1)

22.4

(8.8

, 40.

0)

9.8

(7.8

, 12.

1)

2.0

(0.7

, 4.7

)

17.4

(9.9

, 26.

4)

5.3

(0.1

, 26.

0)

10.6

(9.6

, 11.

8)

ES (9

5% C

I)

7.1

(0.2

, 33.

9)

2.7

(1.7

, 4.0

)44

.8 (4

1.8,

47.

9)

10.6

(6.2

, 16.

6)

15.3

(14.

3, 1

6.4)

11.1

(2.4

, 29.

2)

9.9

(8.8

, 11.

1)

4.4

(3.8

, 5.0

)

18.4

(15.

7, 2

1.2)

57.4

(53.

8, 6

1.0)

51.7

(49.

8, 5

3.5)

26.5

(23.

6, 2

9.5)

36.6

(35.

5, 3

7.7)

15.3

(12.

1, 1

8.9)

18.9

(14.

3, 2

4.3)

8.1

(1.8

, 17.

1)

20.0

(19.

0, 2

1.1)

22.4

(8.8

, 40.

0)

9.8

(7.8

, 12.

1)

2.0

(0.7

, 4.7

)

010

2030

4060

80

DISCLAIMER

All rights reserved.

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