“A meta-analysis of the effectiveness of health belief model variables in predicting behavior” Carpenter, 2010 Natalie Linton Oregon State University October.

“A meta-analysis of the effectiveness of health

belief model variables in predicting behavior”

Carpenter, 2010

Natalie LintonOregon State UniversityOctober 9, 2014

What is the Health Beliefs Model (HBM)?

Developed by the U.S. Public Health Service in the 1950s

Based in value-expectancy theory

http://xkcd.com/51/

measles

What is a meta-analysis?

Statistical methods for contrasting and combining results from different studies

Meta-analyses can identify: patterns sources of

disagreement

Previous HBM meta-analyses:

Janz & Becker 1984 barriers, benefits, susceptibility did not estimate mean effect sizes

Harrison et. al. 1992 retrospective studies = larger

effect sizes than prospective did not correct effect size

estimates

Zimmerman & Vernberg 1994 HBM prediction weak compared to

Social Cognitive Theory and TRA did not examine the effects of

each variable on behavior

Why did Carpenter conduct a meta-analysis of the HBM?

Determine whether measures of HBM concepts could longitudinally predict behavior

Which elements are strong predictors?

What are the moderators?

Moderators found: Time between variable measurement

(Time 1) and outcome behavior measurement (Time 2)

Type of outcome behavior:Prevention or treatmentDrug-taking or not drug-related

Methodology

18 studies (2,702 subjects); published 1982-2007

Looked at only the first 4 concepts of HBM:Susceptibility (18), severity (17), barriers (17), benefits

(15)Studies had to include at least 2 of the 4

Studies had to be longitudinalTime 1: measure HBM variablesTime 2: measure health-related behavior outcome

Outcome dichotomized as treatment (8 studies) or prevention behavior (10 studies)

Outcome also dichotomized as drug-taking behavior (5 studies) or other behavior (13 studies)

Results

Results

Perceived susceptibility

Usually not correlated with health behavior (weakest predictor)

Estimates mostly homogenous

Subset of drug-taking studies only set for which susceptibility was positively correlated with behavior

Moderator: length of timeLonger periods of time between Time 1 and Time 2

associated with weaker effectsr = -0.50

Perceived severity“There is something about about considering

complying with a prescription to take drugs that causes people to consider the severity of the consequences for not taking the drugs more so than for other health behaviors”

Moderator: length of timeSeverity ratings more likely to be positively

correlated to behavior if the behavior is measured shortly after Time 1

r = -0.37

Perceived benefits and barriers

Strongest predictors of behaviorsStronger when dealing with

preventive behavior

Findings mostly consistent with previous literature

Moderator for perceived benefits: length of timeLonger periods of time

between Time 1 and Time 2 associated with weaker effects r = -0.59

http://xkcd.com/388/

Limitations

Small number of studies

Not enough articles providing effect sizes

Variety and varying quality of measures used

16 (of 18) articles relied on convenience samples

Did not test more complex models that are possible and would be better to test (studies would have needed to report full correlation matrices)

DECISIONS/INTENTIONS

SOCIAL SITUATION

BIOLOGY/PERSONALITY

ATTITUDESTOWARD THE

BEHAVIOR

SOCIALNORMATIVE

BELIEFS

Trial Behavior

EXPERIENCES: Expectancies -- Social Reinforcements -- Psychological/Physiological

SELF-EFFICACYBEHAVIORAL

CONTROL

Nurture/CulturalBiological/NatureIntrapersonal Stream Social/Normative Stream Cultural/Attitudinal Stream

Values/Evaluations

Knowledge/Expectancies

PerceivedNorms

Information/Opportunities

InterpersonalBonding

SocialCompetence

Interactions w/Social Instit’s

Others’Beh & Atts

Motivationto Comply

Skills:Social+General

Sense ofSelf/Control

SelfDetermination

1 2 3

7 8 9 10 11 12

13 14 15 16 17 18

l

4 5 6

19 20 21

22

23

DistalInfluences

ProximalPredictors

Levels ofCausation

UltimateCauses

Social/Personal Nexus

Expectancies & Evaluations

Affect andCognitions

Decisions

Experiences

a

b c d e

f

g h i

jk m n

o

p q r

s

t u v w

x

Related BehaviorsJ

K

CF

IB E HA D G

CULTURALENVIRONMENT

Discussion

Why do you think Carpenter found perceived susceptibility to have almost no relationship to health behavior?

Why do you think time between measures worked as a moderator for susceptibility, severity, and benefits?

Why was time between measurements not a moderator for barriers?

References Christopher J. Carpenter (2010): A Meta-Analysis of the

Effectiveness of Health Belief Model Variables in Predicting Behavior, Health Communication, 25:8, 661-669.

DiClemente, R.J., Salazar, L.F., & Crosby, R.A. (2013). Health Behavior Theory for Public Health: Principles, Foundations and Applications. Jones and Bartlett, Boston, MA.

TTI slides provided to H 571 class at Oregon State University.