Suicidal risk factors and completed suicide:
meta-analyses based on psychological autopsy studies
Kouichi Yoshimasu Æ Æ Chikako Kiyohara Æ Æ
Kazuhisa Miyashita Æ Æ The Stress Research Group of the Japanese Society for Hygiene
Received: 6 December 2007/Accepted: 18 April 2008/Published online: 19 June 2008
? The Japanese Society for Hygiene 2008
the effects of common risk factors for suicide by meta-anal-
yses using data extracted from studies based on the
psychological autopsy method. We focused on five common
risk factors of suicide: substance-related disorders, mood
disorders, adverse marital status, adverse employment status,
and self-harm behaviors. A total of 24 articles were identified
from MEDLINE in which the crude odds ratio (OR) could be
calculated for the above five risk factors through 30 April
2007, using such search keywords as ‘‘suicide,’’ ‘‘psycho-
logical autopsy,’’ and ‘‘case-control study.’’ Overall, both
substance-related disorders [OR = 5.24; 95% confidence
interval(CI) =3.30–8.31]andmooddisorders[OR = 13.42;
95%CI = 8.05–22.37]werestronglyassociatedwithsuicidal
risk. Suicidal attempt and deliberate self-harm, which can
strongly associated with suicidal risk [OR = 16.33; 95%
CI = 7.51–35.52]. Effects of social factors such as adverse
marital and employment status were relatively small. As
The purpose of the present review is to evaluate
associated with an increased risk of completed suicide, the
attention. The effective prevention of suicide depends on
whether we can successfully incorporate these personal fac-
tors as well as social factors into an adequate multi-factorial
Case-control study ? Epidemiology ? Meta-analysis
Psychological autopsy ? Suicide ?
Suicide is a serious problem all over the world. Approxi-
mately 1 million people are estimated to commit suicide
per year . Recent figures also show that more than
30,000 people commit suicide each year in Japan. Several
epidemiologic studies [2–8] have indicated risk factors
for suicide, such as depression, severe anxiety, substance
abuse, poor interpersonal relationships including social
isolation, inability to maintain a job, anhedonia, somatic
diseases, financial problems, and personal or familial his-
tory of suicide.
These suicidal risk factors can be divided broadly into
two categories, personal and social factors. The former
are, for example, mental disorders, including genetic
vulnerability (familial history of suicide), physical disor-
ders, and psychological isolation. The latter include socio-
economic or familial factors, such as divorce, unem-
ployment, and stressful life events. It can be assumed that
the interactive effects of these two factors may attenuate
personal tolerance against stressors and lead him/her to
suicide. Kaplan and Sadock  show 13 major suicidal
risk factors ranked according to their association with
suicide. Alcohol dependence, prior suicidal behavior,
Members of the Stress Research Group of the Japanese Society for
Hygiene are listed in the Appendix.
K. Yoshimasu (&) ? K. Miyashita
Department of Hygiene, School of Medicine,
Wakayama Medical University, 8-1-1 Kimiidera,
Wakayama 641-0012, Japan
Department of Preventive Medicine,
Graduate School of Medical Sciences,
Kyushu University, Fukuoka, Japan
Environ Health Prev Med (2008) 13:243–256
depression, unemployed or retired, single, widowed, and
divorced are included. These factors can be clearly
defined independent of the study designs. The other fac-
tors except age and race, such as irritation, loss of
physical health, or unwilling to accept help, are concep-
tually obscure; that is, they are likely to be defined
differently by each epidemiologic study design and to be
affected by the value system in each country with dif-
ferent cultural backgrounds.
To establish an effective suicide prevention model, the
strength of association between those risk factors and
completed suicide should be estimated by an appropriate
statistical method. Meta-analysis is a useful statistical
method in this regard. However, the commonly evaluated
risk factors should be included in this analysis, because the
combined effect of differently defined factors on suicide is
difficult to determine.
As an effective method for identifying the risk factors
associated with completed suicide, psychological autopsy
is one of the most valuable research tools. Usually, face-to-
face structured interviews or semi-structured interviews
with family members of suicide victims or their next of kin
are conducted in detail, with informed consent obtained
beforehand. Sometimes, their close friends, sweethearts,
supervisors, and doctors can be subjects for interview. In
some cases, several months are needed for the interview
period, during which the time for curing the bereaved
families is included.
This retrospective approach of psychological autopsy
can be given an epidemiologic case-control design by
using appropriate controls. The selection of control sub-
jects usually depends on the purpose of the study.
Usually, accident victims (e.g., traffic accidents) or cases
of natural death are compared with the suicide victims.
This study design has come into wide use in Western and
Oceanian countries, China or Taiwan in Asia. However,
to our knowledge, no psychological autopsy studies have
been conducted in Japan thus far. In order to gain reliable
evidence, such a study should be widely conducted in
Japan as well as overseas. Although social factors affec-
ted by the different cultural characteristics are difficult to
compare to one another, it is necessary to provide basic
information of relevant suicidal risk factors for promoting
future Japanese psychological autopsy studies. For this
purpose, the accumulated evidence regarding the com-
monly defined factors in the foreign psychological
autopsy studies should be clearly summarized by the
appropriate statistical method.
From this point of view, the aim of the present article is
to review and evaluate associations between suicidal risk
factors that are cross-culturally defined and completed
suicide, based on the reports that use the method of psy-
chological autopsy with case-control study design.
Identification and selection of relevant studies
We conducted MEDLINE, Current Contents and Web
of Science searches using ‘‘psychological autopsy,’’ ‘‘sui-
cide,’’ and ‘‘case-control study’’ as keywords to search for
papers published from 1990 to 30 April 2007. A total of 61
studies were identified by the above keywords. One addi-
tional article was identified from the references cited in the
first series of articles selected. Articles included in the
meta-analysis were in the English language, published in
the original, and had no obvious overlap of subjects with
other studies (three non-English and one review article
were excluded). We also excluded studies with the same or
overlapping data by the same authors (two articles). Fur-
thermore, for the purpose of this review, 13 articles dealing
with only a specific population, such as those with mental
disorders, were excluded.
As for the suicidal risk factors, we focused on the fol-
lowing four factors: mental disorders (mood disorders and
substance-related disorders), marital status, employment
status, and deliberate self-harm or suicidal attempt. As
mentioned earlier, these factors were more commonly
defined in each study compared with other factors, such as
stressful life events or interpersonal problems, which are
defined differently according to each study design. For
instance, as many studies assessed mental disorders by the
widely used standard diagnostic criteria, such as DSM-IV
or ICD-10, the assessments of these disorders are consid-
ered to be homogenous.
The articles were limited to those in which the crude
odds ratio (OR) could be calculated by 2 9 2 cross tables
(19 articles excluded deal with case series or no relevant
information on the concerned factors). Although almost all
of the relevant studies selected age- or sex-matched control
for each case, only crude ORs were extracted because the
OR calculated by the conditional logistic procedure could
not be reflected in the meta-analyses. Consequently, some
particular factors, such as schizophrenia, had to be exclu-
ded in the present meta-analyses because there were no
subjects with schizophrenia in the control groups in many
studies, despite the fact that schizophrenia is one of the
serious suicidal risk factors. A total of 24 articles were
eligible in the present analysis.
Data extraction and assessment of study quality
For each study, characteristics, such as authors, year of
publication, country of the study population, source of
control population, number of cases and controls, diagno-
ses, diagnostic criteria in case of mental disorders, and
crude OR, were noted.
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