Deliberate self-harm before psychiatric admission and risk of suicide: survival in a Danish national cohort

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Social Psychiatry and PsychiatricEpidemiologyThe International Journal for Researchin Social and Genetic Epidemiology andMental Health Services ISSN 0933-7954Volume 48Number 9 Soc Psychiatry Psychiatr Epidemiol(2013) 48:1481-1489DOI 10.1007/s00127-013-0690-2

Deliberate self-harm before psychiatricadmission and risk of suicide: survival in aDanish national cohort

Trine Madsen, Esben Agerbo, PrebenB. Mortensen & Merete Nordentoft

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ORIGINAL PAPER

Deliberate self-harm before psychiatric admission and riskof suicide: survival in a Danish national cohort

Trine Madsen • Esben Agerbo • Preben B. Mortensen •

Merete Nordentoft

Received: 17 December 2012 / Accepted: 9 April 2013 / Published online: 23 April 2013

� Springer-Verlag Berlin Heidelberg 2013

Abstract

Purpose Psychiatric illness and deliberate self-harm

(DSH) are major risk factors of suicide. In largely 15 % of

psychiatric admissions in Denmark, the patient had an

episode of DSH within the last year before admission. This

study examined the survival and predictors of suicide in a

suicidal high-risk cohort consisting of hospitalized psy-

chiatric patients with recent DSH.

Methods This national prospective register-based study

examined all hospitalized psychiatric patients who self-

harmed within a year before admission. All admitted

patients, in the time period 1998–2006, were followed and

survival analyses techniques were used to identify predic-

tors of suicide.

Results The study population consisted of 17,257

patients; 520 (3 %) died by suicide during follow-up; 50 %

of the suicides occurred within a year from the index

admission. A rate of 1,645 suicides per 100,000 person–

years in the first year after psychiatric admission was

found. Adjusted analyses showed that a higher degree of

education, having DSH within a month before psychiatric

admission and contact with a private psychiatrist increased

the risk of suicide.

Conclusions Psychiatric hospitalized patients with recent

DSH revealed high suicide rates, even during hospitaliza-

tion. When discharging psychiatric patients with recent

DSH careful arrangement of follow-up treatment in the

outpatient setting is recommendable.

Keywords Self-harm � Suicide � Psychiatry �Epidemiology � Survival

Introduction

Psychiatric illness and deliberate self-harm (DSH) are both

major risk factors for completed suicide [1–6]. Hospitalized

psychiatric patients have a long-term prevalence of dying by

suicide on 4–5 % and those patients who in addition have a

history of DSH have a twice as high suicide risk (8–10 %) [7,

8]. Studies examining the risk of suicide among patients

treated for DSH have repeatedly showed that the risk of

suicide is highest within the first year after a non-fatal suicide

and that patients with DSH who have received psychiatric

treatment have an increased suicide risk compared to those

with no psychiatric treatment [9–20].

In about 1/3 of psychiatric admissions in Denmark the

patient has had a previous DSH episode [21], in fact in

15 % of the admissions the DSH episode occurred within

the last year, thus many patients appear at the psychiatric

clinic with two major suicidal risk factors: psychiatric ill-

ness and a recent episode of DSH. Whether the risk of

subsequent suicide differs in patients according to how

recent their episode of DSH was before the psychiatric

hospitalization is yet unexplored. For example, is the

T. Madsen (&) � M. Nordentoft

Psychiatric Center Copenhagen, Copenhagen University

Hospital, Bispebjerg Bakke 23, Building 13A,

2400 Copenhagen, Denmark

e-mail: [email protected]

M. Nordentoft


E. Agerbo � P. B. Mortensen

National Center of Register-based Research,

University of Aarhus, Taasingegade 1,

8000 Aarhus C, Denmark


P. B. Mortensen


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Soc Psychiatry Psychiatr Epidemiol (2013) 48:1481–1489

DOI 10.1007/s00127-013-0690-2

Author's personal copy

immediate risk of suicide higher in patients who received

no psychiatric hospital treatment in relation to their DSH

episode compared to those who were psychiatrically hos-

pitalized just after an episode? Knowledge of this could be

useful for psychiatric staff who daily assess suicidal risk in

psychiatric patients with a history of DSH. Furthermore,

getting a better understanding of factors associated with

suicide in this suicidal high-risk population, who are

already in contact with the mental health care system, may

enhance our possibility to identify and aid patients in a

suicidal crisis.

Both social and clinical characteristics are important

predictors of completed suicide; however, to our knowl-

edge these factors have not previously been examined in a

national cohort of psychiatrically hospitalized patients with

recent DSH. In addition, we wanted to highlight the risk of

completed suicide among patients admitted to psychiatric

hospital soon after an episode of DSH compared to the risk

in patients who had an episode of DSH more than 6 months

before the psychiatric admission.

Aims of the study

We aimed at estimating the survival, suicide rates and

predictors of suicide in a national cohort of psychiatric

patients who had an episode of DSH within a year before a

psychiatric hospital admission using register-based data.

Materials and methods

We had information on all psychiatric admissions in

Denmark from 1998 to 2006 from The Danish Psychiatric

Central Register [22], which covers all psychiatric inpatient

facilities in Denmark and contains longitudinal information

on all admissions and discharges since 1969. Since 1995,

data on psychiatric outpatient treatment has also been

recorded in this register. By the unique ten-digit identifier

number [23] assigned to all persons living in Denmark we

merged data from four other Danish longitudinal registers

to patients admitted to psychiatric inpatient care. Infor-

mation on hospital-treated DSH was retrieved from The

Danish Patient Registry [24]. From the health Insurance

Register [25], we merged information on all outpatient

private psychiatric and private psychologist appointments

subsidized or partly subsidized by the authorities. Finally,

the Integrated Database for Longitudinal Labor Market

Research gathers information annually on the entire pop-

ulation living in Denmark as of 31 December from several

administrative registers from 1980 onward [26].

From The Danish Cause of Death Register [27]

recordings of suicide according to The International Clas-

sification of Diseases, 10th revision [28] (ICD-10) codes

X60–X84 were obtained for the period from 1 January

1997 to 31 December 2006.

There are no private psychiatric hospitals in Denmark,

and all inpatient and outpatient treatment is free of charge

for all Danish citizens and persons with residence permit.

The study population included hospitalized psychiatric

patients with DSH within the last year before the date of

psychiatric admission aged 18 years or older in the period

from 1998 until 2006. Patients were followed from their

index admission, which was defined as the first psychiatric

admission preceded by an episode of DSH within the last

year.

Admissions with a DSH were registered in The Danish

Patient Registry. The recordings of DSH are not a straight

forward procedure in Denmark thus it was defined in the

following way, which has been validated in a Danish study

[29];

1. All hospital contacts with a cause of contact 4

(admitted because of suicide attempt/self-harm).

2. All contacts with a primary diagnosis of mental illness

and a secondary diagnosis with poisoning in ICD-10

code T36–T50 (medication and biological compounds)

or T52–T60 (chiefly non-medical compounds).

3. All contacts with a primary diagnosis of mental illness

and a secondary diagnosis with a cut lesion on

forearm, wrist or hand (ICD-10 code S51, S55, S59,

S61, S65 or S69).

4. All primary poisoning diagnosis with the following

ICD-10 codes: T39, T40, T42, T43, and T58.

It was found that this definition identified up to 70 % of

patients admitted with DSH (the remaining admitted

because of habitual self-mutilation with no suicidal inten-

tion and admissions due to non-intended poisoning).

The study included 17,257 patients with a median age

on 40 years (interquartile range 29 and 52) and in this

population more women (n = 9,462) than men

(n = 7,795) were psychiatrically admitted within a year

after DSH.

Information on clinical variables

Primary ICD-10 diagnosis given at the psychiatric admis-

sion was used. Diagnoses were categorized into substance

abuse (ICD-10 code F1), schizophrenia spectrum (ICD-10

code F2), affective disorders (ICD-10 code F3), adjustment

or stress-related disorders (ICD-10 code F4) or personality

disorders (ICD-10 code F6), and all others. Associations

between secondary diagnoses and suicide were also stud-

ied; substance abuse, affective disorders and personality

disorders (ICD-10 code F60). The number of psychiatric

admissions before the study period was also included in the

analyses to adjust for psychiatric history.

1482 Soc Psychiatry Psychiatr Epidemiol (2013) 48:1481–1489

123


Clinical outpatient care was defined according to whe-

ther a patient received (1) psychiatric outpatient treatment,

or consulted, (2) a private psychiatrist, or (3) a private

psychologist during the last year before the present psy-

chiatric admission.

Patients were categorized into four exclusive groups

according to the time between the date of the DSH and the

date of the psychiatric admission; as to whether the DSH

episode had happened in the last week, 1–3 weeks, 1–6 or

6–12 months before the psychiatric admission.

Information on social variables

We had information on the following socio-demographic

variables; Gross annual income (wages, pensions, unem-

ployment and social security benefits, and interest rates)

which was grouped into age–sex–year population-based

quartiles (i.e., also based on those who had never been

hospitalized); Employment status was divided into being

employed (including adolescents, students, housewives

without labor market attachment and patients with sick

benefits), unemployed, early retirement, and retired. The

Level of education was grouped into elementary school

(9 years in school), high school, vocational training, or a

bachelor degree or higher. Cohabitation status was divided

into five categories: (1) cohabiting/married (cohabiting is

defined as couples of the opposite sex who live together

with shared address and an age difference of less than

15 years and who are not first-degree relatives), (2)

unmarried and living alone, (3) divorced, (4) widowed or

(5) other living status.

Lastly, in the analyses, patients were divided into five

age groups: 18–30, 31–40, 41–50, 51–60 and over 60 years

and these age groups were incorporated in the analyses as

one quantitative covariate.

Generally, for both the clinical and the social variables

the categories in each variable that ordinarily in literature

has the lowest risk of suicide were chosen as the reference

group. One exception was the variable describing admis-

sion diagnosis where we chose the category which included

most patients (those with an affective diagnosis) as we

wanted our reference group to characterize the largest

proportion of the patient case mix. This choice yielded

more relevant clinical information compared to having one

of the less populous categories as reference.

Statistical analysis

Simple statistic procedures were carried out to illuminate

patient characteristics and suicide rates. Kaplan–Meier

curves were performed to illustrate the proportion of

suicide related to psychiatric diagnosis, the timing of

DSH and educational level and by log rank test we

assessed statistically differences in the survival of these

covariates [30]. In Cox regression analyses, we examined

covariates as predictors of suicide. Follow-up time star-

ted at the date of psychiatric admission until death or

until the final censoring date the 31 December 2006.

Mean follow-up time was 1,514 days (just over 4 years).

The covariates were divided into two domains: social

variables and clinical related variables. A three-step

model of analysis was chosen. First step showed all

covariates association with suicide (referred to as the

univariable analyses). Second, assessments of explanatory

variables of suicide in each domain were carried out in

multivariable analyses. The final step (the joint multi-

variable analyses) included the significant predictors

(P value \0.05) from both the social and clinical domain

to assess independent predictors of suicide in multivari-

able analyses thereby adjustment for each domain were

taken into account.

Results

Out of the 17,257 patients, 520 patients died from suicide

during follow-up (3 %) and 1,859 (11 %) died from other

causes. Before being discharged from the current psychi-

atric admission, 32 of the patients died by suicide (6 % of

the suicides) while another 66 (13 %) completed suicide

within a month after discharge and another 261 (50 %)

within a year from psychiatric admission. Overall, the

suicide rate was 727 per 100,000 person–years and the rate

of suicide in the first year after psychiatric admission was

1,645 per 100,000 person–years (See Table 1). The rates

for men with DSH in the month before admission were

high, and in particular men had suicide rates up to 3,000

per 100,000 person–years within the first year. The same

pattern was seen in women, although with fairly lower

rates.

Survival curves

Figure 1 illustrates survival curves in relation to diagnosis

(Fig. 1a), time of DSH episode before psychiatric admis-

sion (Fig. 1b) and educational level (Fig. 1c). The curve

showing the survival by diagnosis indicates that in partic-

ular patients with an affective disorder or those with ‘‘other

diagnosis’’ had a higher risk of dying from suicide, espe-

cially in the first year after admission. Also the survival for

patients with DSH in the week or month before admission

decreased significantly faster compared to patients with

DSH more distant in time before the psychiatric admission.

The survival for patients with the highest educational

degree decreased rapidly in the first year compared to the

survival amongst patients with a lower level of education.

Soc Psychiatry Psychiatr Epidemiol (2013) 48:1481–1489 1483

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Cox regression

Table 2 shows the Cox regression analyses of the associ-

ations between social and clinical covariates with suicide.

In the multivariable analyses of the social domain vari-

ables, only educational- and labor market status demon-

strate statistically significant estimates, pointing toward a

higher risk of suicide among patients with higher educa-

tional background and patients who are employed. Living

status and income level lost significance when adjusted for

the other social variables. The univariate analyses indicated

that patients with an affective disorder at psychiatric

admission had a higher statistically significant risk of sui-

cide during follow-up, but this effect faded when adjusting

for the other clinical variables (Table 2). Having an epi-

sode of DSH within a month before admission or having

met with a private psychiatrist before psychiatric admission

significantly increased the risk of suicide in the multivari-

able model including only the clinical-related variables.

Table 2 shows the results of the joint analyses. Labor

market affiliation was only borderline significant when

carried into the joint analyses, however, educational level

still showed significant results. Patients with the lowest

level of education or those with vocational training had a

decreased risk of suicide compared to patients with a

bachelor degree or higher [HR = 0.67; confidence interval

(CI) 0.51–0.88 and HR = 0.70; CI 0.53–0.94, respec-

tively]. Only patients diagnosed with substance abuse had a

significantly lower risk of suicide compared to patients

with affective disorders (HR = 0.72; CI 0.54–0.95). DSH

within the last month before psychiatric admission was still

significantly associated to suicide compared with those

with DSH prior to 6 months before admission (HR = 1.56;

CI 1.08–2.25 and HR = 1.59; CI 1.01–2.50, respectively).

Contact with a private psychiatrist increased the risk of

suicide (HR = 1.39; CL 1.09–1.78). Finally, males had a

significantly higher hazard of suicide compared to females

(HR = 1.77; CI 1.48–2.11) and the risk of suicide

increased by increasing age group at the index admission

(HR = 1.26; CI 1.16–1.38).

In sub-analyses, we wanted to test whether the clinically

related variables had more importance in terms of pre-

dicting a suicide occurring during or shortly after an

admission as a reflection of the presence of severe psy-

chiatric symptoms. Hence, analyses of predictors for

completed suicide in the first year after psychiatric

admission were carried out. These analyses (including 261

suicides) revealed the same as the above joint analyses,

except primary diagnosis lost statistical significance

(results not shown). Following this, we also examined

predictors (including 224 suicides) of one-year follow-up

suicide among only those with DSH in the last month

before psychiatric admission, revealing that only male sex,

higher age group, lower education and being employed

(compared to unemployed) significantly increased the

short-term suicide risk (results not shown).

Discussion

Three percent of psychiatric inpatients with DSH within

the last year died from suicide and their suicide rates were

very high during first year after receiving psychiatric

inpatient care. Almost one-fifth of the 520 suicides died

Table 1 Suicide rates in (1) the general population of Denmark, (2) the study population and (3) and in relation to time of suicide attempt before

psychiatric admission

Suicide rates per 100,000 person–years (95 % confidence interval)

One-year follow-up Overall

Women Men All Women Men All

General

population,

DKa

7 21 14 – – –

Study

population

1,169 (951–1,409) 2,227 (1,891–2,577) 1,645 (1,462–1,859) 588 (502–669) 900 (806–1,013) 727 (665–790)

Time of suicide attempt

Last week 1,425 (1,153–1,764) 2,348 (1,920–2,839) 1,844 (1,594–2,103) 663 (564–773) 934 (809–1,063) 785 (706–864)

8–30 days 886 (380–1,771) 3,063 (1,701–4,934) 1,814 (1,161–2,685) 599 (371–913) 1,110 (754–1,626) 813 (597–1,079)

31 days–

6 months

643 (241–1,285) 1,935 (1,222–3,056) 1,213 (808–1,752) 385 (245–577) 942 (666–1,286) 625 (477–804)

[6 months ago 376 (125–1,129) 1,039 (445–2,078) 680 (340–1,224) 375 (225–624) 473 (266–768) 420 (284–609)

Rates displayed by gender and different follow-up timea Suicide rates from Denmark in year 2000. Rates from The Danish National Board of Health (no estimated confidence intervals)


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during the present admission or within a month after dis-

charge. Regression analyses revealed that male sex, higher

age at admission, being highly educated, DSH within a

month before admission and having had contact with pri-

vate psychiatric treatment carried a higher risk of suicide.

To our knowledge, this is the first national cohort study

to explore clinical and social predictors of suicide in a

suicidal high-risk group defined as patients who receive

psychiatric inpatient care within a year after DSH. In our

study population, approximately 3 % died of suicide during

a mean follow-up period of 4 years, which corresponds

well with the results of a systematic review [31, 32] of

suicide after DSH that found that 3 % of patients with DSH

completed suicide within 1–4 years of follow-up.

Comparing rates of suicide, we found very high rates of

suicide of 727 and 1,645 per 100,000 person–years overall

and during first year after admission, respectively, com-

pared with the study by Cooper et al. [9] who found suicide

rates of 371 and 562 per 100,000 person–years overall and

during the first 6 months, respectively. Jenkins et al. [18]

report an overall suicide rate over a 22-year follow-up

period of 430 suicides per 100,000 person–years and a

5-year follow-up rate of 590 among patients admitted to

hospital with self-harm. This difference in rate estimates

could be explained by variation in study-populations; the

other studies have followed all patients with DSH and we

examined only patients with DSH who also received psy-

chiatric inpatient care. In addition, when comparing the

results, it is important to take into account that our study

population was followed in time from psychiatric admis-

sion, not in time from DSH episodes as in the other studies.

The results from the Cox regression analyses of the

social variables are parallel to studies, which have shown

that some socio-demographic risk factors for suicide are

upside down in patients who received psychiatric hospital

care [33, 34] compared to what studies of suicide predictors

have found in the general population where employment,

marriage and high income seem to predict a lower risk of

suicide [35, 36]. Two other studies examined employment

status among patients with DSH [9, 15] and found no

significant association with suicide; however, both studies

included small numbers of patients dying by suicide

(n \ 61). An explanation of this reverse association

between suicide and high educational level could be that

patients working or highly skilled suddenly find themselves

in a stressful situation (with both a recent DSH episode and

a psychiatric admission) where they suddenly risk losing

their job, and/or the ability to use their education, thereby

putting them at risk of suicide. However, these indications

of reverse associations between social variables and suicide

could also be due to misclassifications, if a patient had lost

a job, income or had changes in marital status in the year of

Fig. 1 a Kaplan–Meier curves illustrating the proportion of suicide

associated to diagnosis. b Kaplan–Meier curves illustrating the

proportion of suicide associated to time of suicide attempt before

psychiatric admission. c Kaplan–Meier curves illustrating the pro-

portion of suicide associated to educational level


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Table 2 Shows the frequency of suicides and patients, and the association between suicide and covariates in the Cox regression analyses

Characteristics Suicides (n)/patients (n) Hazard ratio (95 % CI)

Univariable Multivariablea Joint analyses

Social covariates

Labor market status

Employed 229/7159 1 1 1

Unemployed 86/3,890 0.68 (0.53–0.87) 0.77 (0.60–0.99) 0.80 (0.62–1.03)

Early retirement 126/4,444 0.88 (0.70–1.09) 0.80 (0.63–1.02) 0.81 (0.63–1.03)

Retired 76/1,633 1.73 (1.34–2.25) 1.05 (0.74–1.51) 1.04 (0.73–1.47)

Unknown 3/131 0.84 (0.27–2.62) 0.97 (0.15–6.09) 1.15 (0.34–3.82)

Gross incomec

Highest quartile 64/1,763 1 1

Third quartile 89/2,375 1.00 (0.72–1.37) 1.01 (0.73–1.40)

Second quartile 111/3,552 0.82 (0.60–1.11) 0.86 (0.63–1.17)

Lowest quartile 253/9,436 0.68 (0.52–0.90) 0.75 (0.56–1.02)

Unknown 3/131 0.69 (0.22–2.20) d

Educationc

Bachelor degree or higher 71/1,475 1 1 1

Vocational training 143/4,328 0.66 (0.50–0.88) 0.64 (0.49–0.85) 0.70 (0.53–0.94)

High school 33/1,082 0.59 (0.39–0.90) 0.86 (0.56–1.31) 0.84 (0.55–1.29)

Primary school 243/9,258 0.51 (0.40–0.67) 0.68 (0.51-0.90) 0.67 (0.51-0.88)

Unknown 30/1,114 0.57 (0.37–0.87) 0.53 (0.34–0.85) 0.56 (0.36–0.89)

Living status

Married/cohabiting 231/6,473 1 1

Living alone/not married 162/6,961 0.65 (0.53–0.79) 0.82 (0.65–1.03)

Divorced 83/2,755 0.85 (0.66–1.09) 0.84 (0.65–1.08)

Widow 39/885 1.38 (0.98–1.94) 1.11 (0.76–1.62)

Other living status 5/183 0.84 (0.35–2.03) 1.05 (0.26–4.24)

Clinical covariates

Admission Diagnosis

Affective diagnosis 161/4,120 1 1 1

Substance abuse 84/3,450 0.59 (0.46–0.77) 0.66 (0.50–0.88) 0.72 (0.54–0.95)

Schizophrenia 75/2,895 0.61 (0.46–0.80) 0.83 (0.61–1.12) 0.85 (0.63–1.15)

Adjustment and stress disorder 93/3,399 0.69 (0.53–0.89) 0.80 (0.62–1.05) 0.85 (0.65–1.10)

Personality disorder 59/1,873 0.74 (0.55–1.00) 1.11 (0.80–1.53) 1.18 (0.86–1.62)

Other 48/1,520 0.83 (0.60–1.14) 0.90 (0.65–1.25) 0.99 (0.71–1.37)

Secondary diagnosis

Substance abuse (No) 428/14,069 1 1

Substance abuse (Yes) 92/3188 0.97 (0.77–1.22) 0.98 (0.78–1.23)

Affective disorder (No) 493/16,552 1 1

Affective disorder (Yes) 27/705 1.40 (0.95–2.06) 1.34 (0.90–2.00)

Personality disorder (No) 493/16150 1 1

Personality disorder (Yes) 27/1,107 0.80 (0.55–1.19) 0.91 (0.62–1.35)

Timing of suicide attempt before admission

Prior to 6 months 31/1,572 1 1 1

31 days to 6 months 63/2,428 1.41 (0.92–2.16) 1.36 (0.89–2.09) 1.35 (0.88–2.09)

8–30 days 49/1,501 1.79 (1.14–2.81) 1.60 (1.02–2.51) 1.59 (1.01–2.50)

Last week 377/11,756 1.75 (1.21.2.52) 1.58 (1.09–2.28) 1.56 (1.08–2.26)

Private psychiatrist

No 443/15,375 1 1 1


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hospital admission, because we only had information on

social covariates from the year before admission.

Ordinarily, the literature on suicide among psychiatric

patients has found that patients with affective disorders

have a significantly higher risk of suicide compared to

patients with schizophrenia [21, 37]. Yet Tidemalm et al.,

Haukka et al., and our results indicate that the risk of

suicide in patients with DSH who had been hospitalized

with a diagnosis of schizophrenia or unipolar/bipolar dis-

order was similar, thus the type of psychiatric diagnosis as

a predictor of suicide may differ in psychiatric patients

with or without DSH. In sub-analyses, we further tested

whether psychiatric diagnosis (and the other clinically

related covariates) explained more in the cohort of DSH

patients by examining predictors for completed suicide in

the first year after psychiatric admission. These analyses

supported the finding that diagnosis lost impact as a pre-

dictor of suicide in patients who recently self-harmed,

possibly indicating that clinicians should not base suicidal

risk prognosis on specific psychiatric diagnosis. Our results

as well as studies using clinical interviews have estimated

that around 90 % of patients with DSH have a psychiatric

disorder [38, 39], which make it relevant in future studies

to further test the importance of type and severity of psy-

chiatric diagnoses in patients with DSH.

In addition, we also found that contact with a private

psychiatrist appeared to increase the risk. The latter

association could signal that private psychiatrists have

been trained to identify acute suicidal patients and are

accordingly quick to admit them to psychiatric hospital

care; however, we are not able to assess this within our

data.

Patients with a DSH in the month before admission had

a higher risk of suicide during the complete follow-up

period and during the first year after admission. These

patients were most likely in many cases admitted to psy-

chiatric care as they had a present suicidal risk and thereby

a higher risk for completing suicide in the near future,

whereas those with DSH more than 6 months ago had

survived the first period with an elevated suicidal risk after

the DSH episode without receiving psychiatric treatment,

possibly indicating DSH with a lesser degree of suicidal

intent. In essence, our results from a cohort of psychiatric

inpatients with DSH within the last year reflect earlier

studies showing that the risk of completed suicide is

highest in the first period after DSH.

Methodological issues

We had access to data on psychiatric admissions from 1997

to 2006, and as we wanted to ensure that the clinical data

was from the first psychiatric admission after an episode of

DSH, we chose a study period starting from 1998 and to

include only patients with DSH within the last year before

psychiatric admission. Making that choice weakens the

generalizability of our results since it meant that we had to

exclude patients who had an episode of DSH more than a

year before the psychiatric admission, thus our results only

apply to psychiatric inpatients with recent DSH. Adding to

this point, some of the included patients have had earlier

psychiatric admissions. It may have been optimal to follow

only first-time admitted psychiatric patients who recently

self-harmed to avoid studying patients who had survived

the elevated risk of suicide in the first year after first

Table 2 continued

Characteristics Suicides (n)/patients (n) Hazard ratio (95 % CI)

Univariable Multivariablea Joint analyses

Yes 77/1,882 1.44 (1.13–1.83) 1.44 (1.13–1.85) 1.39 (1.09–1.78)

Private psychologist

No 500/16,588 1 1

Yes 20/669 1.03 (0.66–1.60) 1.16 (0.74–1.82)

Psychiatric outpatient

No 435/14,474 1 1

Yes 85/2,783 1.03 (0.82–1.30) 1.07 (0.85–1.36)

No. of psychiatric admission

By increasing admission no. – 0.99 (0.98–1.00) 0.99 (0.98–1.00)

Na not applicablea Adjusted for sex and age group and analyses carried out separately among the social variables and the clinical-related variables, respectivelyc Gross income was not adjusted for educational level to avoid over-adjustment as well as labor market status, educational level and living status

were not adjusted for gross income because income is closely related to thesed Parameter estimate = 0


123


admission [40]. However, since we did not know whether

this association was of importance in our study population

and to avoid compromising our power, we chose instead to

test whether the number of previous psychiatric admissions

significantly predicted suicide and found no significant

difference. Another point to emphasize is, that we only had

access to information on DSH through register-based data,

hence patients who had a less physically harming episode

of DSH is in most cases not registered as this would not

lead to hospitalization. Therefore, the true cohort of psy-

chiatric patients with recent DSH is probably larger in size,

yet we believe our cohort almost certainly includes those at

highest suicidal risk and another point to highlight is that

our defined cohort is identifiable for the clinical staff in the

medical files.

We wanted to examine only patients who died from

subsequent suicide after psychiatric admission, therefore to

ensure exclusion of those who were psychiatrically

admitted due to the DSH episode and died from somatic

consequences that DSH episode, we tested whether the

method of the DSH described in The Danish Patient Reg-

istry was the same as the method of the suicide described in

the Cause of Death register and whether the patients were

somatically admitted from the day of the DSH until the day

they were discharged because of suicide. To estimate the

problem size we checked everyone with DSH in the week

before psychiatric admission who also died during the first

week of admission, leaving us in doubt with seven patients.

If they actually died of the DSH episode before admission

then this will lead to a slight overestimation of the results.

In conclusion, this study demonstrated extremely high

suicide rates in a population of patients with DSH who

within a year also received psychiatric inpatient care and

found that DSH within a month before admission and a

higher level of education increased the risk for completing

suicide, in particular within the first year after admission.

Acknowledgments A fund providing support to the prevention of

suicide and suicide attempt administered by The Ministry of Interior

and Social Affairs in Denmark. The authors report no financial or

other relationship relevant to the subject of this article.

Conflict of interest On behalf of all authors, the corresponding

author states that there is no conflict of interest.

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Deliberate self-harm before psychiatric admission and risk of suicide: survival in a Danish national cohort

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