Background
Suicide is a global health concern, with approximately 800,000 persons around the world dying by suicide each year [
1]. The causes of suicide are complex. Current evidence-based models emphasise an interaction between pre-existing vulnerability, in particular psychiatric history, previous self-harm, personality factors, family history of suicide, childhood adversity and precipitant stressors, such as significant loss, relationship breakdown, or other psychosocial crises [
2‐
4].
The profound effects of suicidal behaviour are borne by those who survive an act of self-harm, but also by family members, friends, work colleagues, healthcare professionals, and the wider community [
5,
6]. Those who are bereaved by suicide endure lasting negative effects on their mental and physical health, and are themselves at increased risk of suicidal behaviour [
7‐
9].
Despite its significant societal impact, suicide is a statistically rare phenomenon (with a global rate of 11 per 100,000). Therefore, one of the most efficient ways of studying the determinants of suicide is to examine risk factors retrospectively using a psychological autopsy approach. This approach is based on the “meticulous collection of data that are likely to help reconstitute the psychosocial environment of individuals who have committed suicide and thus understand better the circumstances of their death” [
10]. The approach is useful in assessing psychological characteristics, psychosocial circumstances, health service use and proximal risk or contributing factors associated with suicide, provided that standardised definitions and systematic procedures are used [
11,
12].
Psychological autopsy studies have become more widely used in recent years [
11,
12], but the potential of this approach has yet to be exploited fully. Some psychological autopsy studies fail to include a control group, and where controls are used, methodological shortcomings include an imbalance of available information between cases and controls and absence of a matched comparison between cases and controls [
13,
14]. Recent well-designed psychological autopsy studies are limited to particular groups, such as army soldiers [
15], farmers [
16] and older people living in rural areas [
17] or focussed on specific risks to suicide, such as alcohol use disorder [
18]. Well-designed general population studies are scarce. Moreover, few psychological autopsy studies have compared fatal suicidal behaviour to near-fatal suicidal behaviour to determine the factors specifically associated with a fatal outcome, as well as proximal protective factors preventing suicide. Cases of high-risk self-harm appear to share some characteristics with suicide [
19‐
21] but more research is required to elucidate the characteristics of those who survive a near-fatal act, and to explore the role of high suicidal intent in such acts. Finally, the reliability of the information obtained from various sources in psychological autopsy studies, and how these are reconciled in the absence of self-report, is an ongoing methodological issue that requires further testing of empirical data [
22]. These methodological issues can be overcome for the most with a thoughtful psychological autopsy study design.
Another consideration in designing a psychological autopsy study is the model that will be used to interpret risk factors for suicidal behaviour. The aetiology of suicide is multi-faceted and includes an array of risk and protective factors. The Integrated Motivational Volitional (IMV) model by O’Connor [
3] addresses the transition of suicidal intent to suicidal behaviour while taking into account both individual-level and environmental factors. The IMV model is a diathesis-stress model which specifies components of the pre-motivational, motivational and volitional phases of suicidality, and may therefore provide insight into factors that either increase the risk associated with suicidal behaviour (non-fatal and fatal) or protect effect against suicidal behaviour. The IMV model also allows testing hypotheses on interactions between individual-level (e.g. depression, coping) and environmental (e.g. work-related stress, unemployment) factors.
Although there has been increased recognition of the role of employment and working conditions in suicide during the last global economic recession [
23,
24], so far, work-related factors have only been examined in detail in one previous psychological autopsy study [
25], which is somewhat outdated, involving cases of suicide in Germany some 15 years ago. However, job stressors have been clearly established as risk factors to mental health and there is also scarce research evidence that they are associated with suicide and suicide attempts, specifically skill level [
26], precarious work, lack of social support at work, low control and high job demands [
27‐
30].
The current study follows on from the successful implementation of a psychological autopsy study in Cork, Ireland between 2008 and 2012 [
31‐
34] and aims to address some of the gaps and opportunities outlined above. In keeping with the IMV Model [
3], the objective of the current study is to examine the predictive value of specific psychosocial, psychiatric and work-related factors associated with suicide and near-fatal self-harm in line with existing models of suicidal behaviour, and to explore the consistency of information across multiple sources. Risk and protective factors can be identified by comparing three groups: suicide decedents, emergency department patients presenting with high-risk self-harm, and GP patient controls. We conceptualised psychiatric and psychological factors at the level of the individual (e.g. history of self-harm, individual coping, substance abuse, depression), psychosocial factors at the level of the psychological and social environment of the individual (e.g. social support) and work-related factors at the level of the labour market environment (e.g. job loss, high job demands).
The ideal approach to identify potentially causal risk factors for suicide would be a cohort study. However, this design would require a large sample size and resources beyond the scope of the current study, as suicide is a rare event. At a suicide rate of 11 per 100,000, a community-based cohort study would require just over 900,000 participants to observe 100 suicides over a one-year period. For events with such low incidence, a case-control study design is the most pragmatic [
35].
The following hypotheses will be tested in the actual study: 1) We hypothesise higher prevalence of unemployment and psychosocial work stressors, including high demands, job insecurity, low control and low social support, among the suicide cases compared with GP controls; 2) We hypothesise moderating effects of factors increasing risk of self-harm and suicide (e.g. level of suicidal intent and planning, access to means) and protective factors (e.g. positive coping and quality of social support); 3) In line with the IMV model [
3], we hypothesise that protective factors, such as positive coping, quality of social support, and access to treatment are higher among people who have engaged in high-risk self-harm compared to those who have died by suicide, and 4) We also hypothesise higher levels of these protective factors among the GP controls compared to those who have engaged in high-risk self-harm and those who have died by suicide.
Discussion
The outlined study has the potential to inform suicide prevention practice and research and to advance the methodology of case-control and psychological autopsy research. The study allows investigation of a broad range of risk factors and protective factors for suicidal behaviour due to its unique design of integrating different data sources (primary health practitioner, coroners and family informants). The study also includes three different groups, suicide cases, high-risk self-harm cases and GP controls, allowing for specific comparisons to be made. The comparison between suicide cases and GP controls allows investigation of risk factors and protective factors for suicide more generally, while the comparison with high-risk self-harm patients will help to identify the factors associated specifically with a fatal outcome to a self-harm episode. A particular methodological strength of the SSIS-ACE case control study design is the matching of suicide cases with controls from the same GP practices, thereby controlling for confounders, such as socio-economic aspects and neighbourhood effects. Moreover, the study design pays careful consideration to the potential effects of proxy report on ascertainment of risk and protective factors.
The comparison between the suicide cases and the high-risk self-harm cases will allow for further examination of the specific factors associated with a fatal outcome after a serious suicidal act and the role of less often researched protective factors. This may be particularly relevant to clinical practice, as one particular contribution of this study will be a more in-depth understanding of the precipitating factors that make a self-harm act more or less likely to be fatal. These groups share many common characteristics, however there is little research on factors other than method lethality that account for survival after a high-risk self-harm act.
A further addition to previous research on the determinants of suicidal behaviour is the current study’s particular focus on work-related risk factors for suicide. There is increasing recognition of working conditions as a potential risk factor for suicidal behaviour but also as an environment for the effective delivery of suicide prevention initiatives [
1]. Several large-scale international studies [
24,
62,
63], have shown that the global economic recession was associated with an increase in suicide rates, but the importance of specific work-related factors has been neglected. A more in-depth understanding may inform occupational health practice to develop specific work-related mental health and suicide prevention services and health promotion initiatives. The study results may also inform population based public health strategies and evidence-based policy development and information campaigns in occupational settings as demonstrated by the Australian Programme ‘Mates in Construction’, a community-based suicide prevention programme for the construction industry [
64].
Although the psychological autopsy method has been used in a variety of studies, its methodical soundness has been questioned [
14]. Criticisms include recall bias and information bias, as well as shortcomings with assessing psychiatric diagnoses [
65]. However, the current study does not seek to assign psychiatric diagnoses and is particularly suited for investigating the validity of the psychological autopsy method by systematically analysing the consistencies and inconsistencies of responses across different types of informants.
The proposed optimised psychological autopsy methodology represents advancement compared to other psychological autopsy studies. One of the most comprehensive case-control psychological autopsy studies by Schneider and colleagues [
25], used information from family informants for both suicide and control cases, in addition to interviews with control participants. However, for the suicide cases no additional sources of information were accessed, such as health care professionals, coroners or forensic doctors, and pro-active facilitation of support was not systematically combined with obtaining information from family informants, a limitation that can also be found in more recent psychological autopsy studies [
15‐
17]. In addition, the optimised psychological autopsy method utilizes two comparison groups (matched GP controls and high-risk self-harm cases). It hereby goes beyond the scope of controlled psychological autopsy studies in suicide research with comparison of two groups only [
16,
17,
25,
66,
67] and allows examination of the specific factors associated with a fatal act in comparison to non-fatal but severe self-harm acts. One exception with the use of three groups is the case-control study by Nock et al. [
15], conducted with an army population. This study compared, similar to our study, suicide cases with two groups: a group of living controls without suicide ideation and a group of living controls with self-reported suicide ideation. However, the advantage of including a comparison group involving patients who engaged in high-risk self-harm is that this enables determining the factors specifically associated with a fatal outcome, as well as proximal protective factors preventing suicide.
Dissemination of the research outcomes will be conducted at several levels, through peer-reviewed papers, international scientific conferences, a final study report (to be disseminated among key stakeholders on the local, national and international level), and local seminars. It is anticipated that the outcomes of the study will inform public and occupational health interventions and clinical practice to prevent suicide and clinical management of those who attempt suicide.
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