The case for case-control studies in the field of suicide prevention

Contacts with primary and secondary healthcare before suicide by those under the care of mental health services: case-control, whole-population-based study using person-level linked routine data in Wales, UK during 2000-2015

BACKGROUND

People under the care of mental health services are at increased risk of suicide. Existing studies are small in scale and lack comparisons.

AIMS

To identify opportunities for suicide prevention and underpinning data enhancement in people with recent contact with mental health services.

METHOD

This population-based study includes people who died by suicide in the year following a mental health services contact in Wales, 2001-2015 (cases), paired with similar patients who did not die by suicide (controls). We linked the National Confidential Inquiry into Suicide and Safety in Mental Health and the Suicide Information Database - Cymru with primary and secondary healthcare records. We present results of conditional logistic regression.

RESULTS

We matched 1031 cases with 5155 controls. In the year before their death, 98.3% of cases were in contact with healthcare services, and 28.5% presented with self-harm. Cases had more emergency department contacts (odds ratio 2.4, 95% CI 2.1-2.7) and emergency hospital admissions (odds ratio 1.5, 95% CI 1.4-1.7), but fewer primary care contacts (odds ratio 0.7, 95% CI 0.6-0.9) and out-patient appointments (odds ratio 0.2, 95% CI 0.2-0.3) than controls. Odds ratios were larger in females than males for injury and poisoning (odds ratio: 3.3 (95% CI 2.5-4.5) v. 2.6 (95% CI 2.1-3.1)).

CONCLUSIONS

We may be missing existing opportunities to intervene, particularly in emergency departments and hospital admissions with self-harm presentations and with unattributed self-harm, especially in females. Prevention efforts should focus on strengthening routine care contacts, responding to emergency contacts and better self-harm care. There are benefits to enhancing clinical audit systems with routinely collected data.

Explainable artificial intelligence models for predicting risk of suicide using health administrative data in Quebec

Suicide is a complex, multidimensional event, and a significant challenge for prevention globally. Artificial intelligence (AI) and machine learning (ML) have emerged to harness large-scale datasets to enhance risk detection. In order to trust and act upon the predictions made with ML, more intuitive user interfaces must be validated. Thus, Interpretable AI is one of the crucial directions which could allow policy and decision makers to make reasonable and data-driven decisions that can ultimately lead to better mental health services planning and suicide prevention. This research aimed to develop sex-specific ML models for predicting the population risk of suicide and to interpret the models. Data were from the Quebec Integrated Chronic Disease Surveillance System (QICDSS), covering up to 98% of the population in the province of Quebec and containing data for over 20,000 suicides between 2002 and 2019. We employed a case-control study design. Individuals were considered cases if they were aged 15+ and had died from suicide between January 1st, 2002, and December 31st, 2019 (n = 18339). Controls were a random sample of 1% of the Quebec population aged 15+ of each year, who were alive on December 31st of each year, from 2002 to 2019 (n = 1,307,370). We included 103 features, including individual, programmatic, systemic, and community factors, measured up to five years prior to the suicide events. We trained and then validated the sex-specific predictive risk model using supervised ML algorithms, including Logistic Regression (LR), Random Forest (RF), Extreme Gradient Boosting (XGBoost) and Multilayer perceptron (MLP). We computed operating characteristics, including sensitivity, specificity, and Positive Predictive Value (PPV). We then generated receiver operating characteristic (ROC) curves to predict suicides and calibration measures. For interpretability, Shapley Additive Explanations (SHAP) was used with the global explanation to determine how much the input features contribute to the models' output and the largest absolute coefficients. The best sensitivity was 0.38 with logistic regression for males and 0.47 with MLP for females; the XGBoost Classifier with 0.25 for males and 0.19 for females had the best precision (PPV). This study demonstrated the useful potential of explainable AI models as tools for decision-making and population-level suicide prevention actions. The ML models included individual, programmatic, systemic, and community levels variables available routinely to decision makers and planners in a public managed care system. Caution shall be exercised in the interpretation of variables associated in a predictive model since they are not causal, and other designs are required to establish the value of individual treatments. The next steps are to produce an intuitive user interface for decision makers, planners and other stakeholders like clinicians or representatives of families and people with live experience of suicidal behaviors or death by suicide. For example, how variations in the quality of local area primary care programs for depression or substance use disorders or increased in regional mental health and addiction budgets would lower suicide rates.

Identifying features of risk periods for suicide attempts using document frequency and language use in electronic health records

Background

Individualising mental healthcare at times when a patient is most at risk of suicide involves shifting research emphasis from static risk factors to those that may be modifiable with interventions. Currently, risk assessment is based on a range of extensively reported stable risk factors, but critical to dynamic suicide risk assessment is an understanding of each individual patient's health trajectory over time. The use of electronic health records (EHRs) and analysis using machine learning has the potential to accelerate progress in developing early warning indicators.

Setting

EHR data from the South London and Maudsley NHS Foundation Trust (SLaM) which provides secondary mental healthcare for 1.8 million people living in four South London boroughs.

Objectives

To determine whether the time window proximal to a hospitalised suicide attempt can be discriminated from a distal period of lower risk by analysing the documentation and mental health clinical free text data from EHRs and (i) investigate whether the rate at which EHR documents are recorded per patient is associated with a suicide attempt; (ii) compare document-level word usage between documents proximal and distal to a suicide attempt; and (iii) compare n-gram frequency related to third-person pronoun use proximal and distal to a suicide attempt using machine learning.

Methods

The Clinical Record Interactive Search (CRIS) system allowed access to de-identified information from the EHRs. CRIS has been linked with Hospital Episode Statistics (HES) data for Admitted Patient Care. We analysed document and event data for patients who had at some point between 1 April 2006 and 31 March 2013 been hospitalised with a HES ICD-10 code related to attempted suicide (X60-X84; Y10-Y34; Y87.0/Y87.2).

Findings

n = 8,247 patients were identified to have made a hospitalised suicide attempt. Of these, n = 3,167 (39.8%) of patients had at least one document available in their EHR prior to their first suicide attempt. N = 1,424 (45.0%) of these patients had been "monitored" by mental healthcare services in the past 30 days. From 60 days prior to a first suicide attempt, there was a rapid increase in the monitoring level (document recording of the past 30 days) increasing from 35.1 to 45.0%. Documents containing words related to prescribed medications/drugs/overdose/poisoning/addiction had the highest odds of being a risk indicator used proximal to a suicide attempt (OR 1.88; precision 0.91 and recall 0.93), and documents with words citing a care plan were associated with the lowest risk for a suicide attempt (OR 0.22; precision 1.00 and recall 1.00). Function words, word sequence, and pronouns were most common in all three representations (uni-, bi-, and tri-gram).

Conclusion

EHR documentation frequency and language use can be used to distinguish periods distal from and proximal to a suicide attempt. However, in our study 55.0% of patients with documentation, prior to their first suicide attempt, did not have a record in the preceding 30 days, meaning that there are a high number who are not seen by services at their most vulnerable point.

Characteristics of suicide decedents with no federally funded mental health service contact in the 12 months before death in a population-based sample of Australians 45 years of age and over

INTRODUCTION

More than half of suicide decedents have no contact with mental health services 12 months before death. It is uncertain if they have different characteristics than decedents who use mental health services.

METHODS

A case-series design. Participants 45 years and older, who died by suicide (2006-2018). Comparisons were made between those who did and did not have contact with mental health services, using individually linked data from federal services in the Medicare Benefits Schedule (MBS) and Pharmaceutical Benefits Scheme (PBS).

RESULTS

Of 186 cases, 71% had no contact with mental health services. Physical health services were used equally by 75%. Psychiatric medication use was uncommon, except for antidepressants, 50% with mental health service contact and 20% with no contact. Older age, lower income, involuntarily unemployed, firearms as suicide method, greater physical disability, less functional impairment due to emotional problems and lesser proportions with mental illness, were associated with no contact with mental health services.

CONCLUSIONS

For suicide prevention, middle-older aged adults may have less requirement for mental health intervention, and greater requirement for the development of complementary interventions focused on physical health and social issues, which are not necessarily best delivered by clinical mental health services.

Suicide among transport industry workers: A systematic review and meta-analysis

OBJECTIVES

Working in high-stress and male-dominated occupations is associated with an elevated risk of suicide. The current study sought to conduct the first systematic literature review and meta-analysis aimed at determining suicide risk across the diverse, high pressure and male-dominated transport industry (commercial aviation, merchant seafaring, transit/driving) as compared to the general/employed population.

METHODS

Searches of PubMed/Medline, Scopus and PsycINFO databases were conducted without date restriction until March 2021. Studies were included if they were written in English, were peer reviewed, and presented primary observational research data. Studies referring exclusively to suicidal ideation, suicide attempts, self-harm, and/or accidents were excluded.

RESULTS

Following deletion of duplicates and non-English titles, a total of 4201 titles/abstracts were screened and 92 full-texts were read against inclusion/exclusion criteria. The final included sample consisted of 23 articles (16 used for meta-analysis). Results from the meta-analysis indicated that transport workers had a significantly elevated risk for suicide as compared to the general/employed population. Results were consistent across sensitivity analyses, and there was some variation across subgroup analyses.

CONCLUSIONS

Overall, we found transport workers had a significantly higher risk for suicide than the general/employed population, and this appeared to be driven by the association for those working in merchant seafaring/maritime occupations. The findings are discussed in relation to an identified need for the development, implementation, and evaluation of tailored workplace suicide prevention strategies for transport industry workers.

Risk factors for suicide in adults: systematic review and meta-analysis of psychological autopsy studies

QUESTION

Effective prevention of suicide requires a comprehensive understanding of risk factors.

STUDY SELECTION AND ANALYSIS

Five databases were systematically searched to identify psychological autopsy studies (published up to February 2022) that reported on risk factors for suicide mortality among adults in the general population. Effect sizes were pooled as odds ratios (ORs) using random-effects models for each risk factor examined in at least three independent samples.

FINDINGS

A total of 37 case-control studies from 23 countries were included, providing data on 40 risk factors in 5633 cases and 7101 controls. The magnitude of effect sizes varied substantially both between and within risk factor domains. Clinical factors had the strongest associations with suicide, including any mental disorder (OR=13.1, 95% CI 9.9 to 17.4) and a history of self-harm (OR=10.1, 95% CI 6.6 to 15.6). By comparison, effect sizes were smaller for other domains relating to sociodemographic status, family history, and adverse life events (OR range 2-5).

CONCLUSIONS

A wide range of predisposing and precipitating factors are associated with suicide among adults in the general population, but with clear differences in their relative strength.

PROSPERO REGISTRATION NUMBER

CRD42021232878.

Suicide among young-old and old-old adults in rural China: A case-control psychological autopsy study

OBJECTIVE

Late-life suicide is a vital public health concern. Though gerontological research suggested the young-old and old-old phases were heterogeneous, age differences in the elderly suicide have not been well studied due to the lack of comparable control groups and small samples. The study aimed to examine the age-specific suicidal characteristics and risk factors among the young-old (60-79) and old-old (over 80) elderly.

METHODS

Two hundred and forty two suicide decedents and 242 living comparisons were enrolled in a 1:1 matched case-control psychological autopsy study in rural China: 173 young-old and 69 old-old in each group. Suicidal characteristics, demographic characteristics, living arrangements, physical health, mental disorder, and psychosocial factors were collected. We used logistic regression models to assess risk factors of suicide and test for interactions between age and each risk factor.

RESULTS

Pesticide suicide was more prevalent among young-old suicides than old-old suicides (56.07% vs. 40.58%, p = 0.029). Non-currently married, unemployment, mental disorder, higher disability in physical activities of daily living, higher hopelessness and higher depressive symptom were significantly associated with suicide among older adults. The effect of poor function in physical activities of daily living on suicide was significantly greater during younger ages (p for interaction = 0.038).

CONCLUSIONS

Findings indicated that most suicidal characteristics and risk factors for completed suicide were generally similar among young-old and old-old adults. But poor function in physical activities of daily living predicted increase suicide risk only at younger ages. In addition to common risk factors, age-specific factors should also be noted in suicide prevention.

CLINICAL TRIAL REGISTRATION

According to the ICMJE, purely observational studies (those in which the assignment of the medical intervention is not at the discretion of the investigator) will not require registration. Our study was not registered because this is a case-control study. But all procedures of the study were carried out in accordance with the latest version of the Declaration of Helsinki. The study were approved by the Institutional Review Boards of the Central South University, Shandong University, and Guangxi Medical University.

Healthcare contacts with self-harm during COVID-19: An e-cohort whole-population-based study using individual-level linked routine electronic health records in Wales, UK, 2016-March 2021

INTRODUCTION

Reduced rates of help seeking by those who self-harmed during the COVID-19 pandemic have been reported.

OBJECTIVES

To understand changes in healthcare service contacts for self-harm during the COVID-19 pandemic across primary, emergency and secondary care.

METHODS

This retrospective cohort study used routine electronic healthcare data for Wales, United Kingdom, from 2016 to March 14, 2021. Population-based data from primary care, emergency departments and hospital admissions were linked at individual-level. All Welsh residents aged ≥10 years over the study period were included in the study. Primary, emergency and secondary care contacts with self-harm at any time between 2016 and March 14, 2021 were identified. Outcomes were counts, incidence, prevalence and proportion of self-harm contacts relative to all contacts in each and all settings, as well as the proportion of people contacting one or more settings with self-harm. Weekly trends were modelled using generalised estimated equations, with differences between 2020 (to March 2021) and comparison years 2016-2018 (to March 2017-2019) quantified using difference in differences, from which mean rate of odds ratios (μROR) across years was reported.

RESULTS

The study included 3,552,210 individuals over the study period. Self-harm contacts reduced across services in March and December 2020 compared to previous years. Primary care contacts with self-harm reduced disproportionately compared to non-self-harm contacts (μROR = 0.7, p<0.05), while their proportion increased in emergency departments during April 2020 (μROR = 1.3, p<0.05 in 2/3 comparison years) and hospital admissions during April-May 2020 (μROR = 1.2, p<0.05 in 2/3 comparison years). Despite this, those who self-harmed in April 2020 were more likely to be seen in primary care than other settings compared to previous years (μROR = 1.2, p<0.05). A lower proportion of those with self-harm contacts in emergency departments were subsequently admitted to hospital in December 2020 compared to previous years (μROR = 0.5, p<0.05).

CONCLUSIONS

These findings suggest that those who self-harmed during the COVID-19 pandemic may have been less likely to seek help, and those who did so faced more stringent criteria for admission. Communications encouraging those who self-harm to seek help during pandemics may be beneficial. However, this needs to be supported by maintained provision of mental health services.

Association of parenting with suicidal ideation and attempts in children and youth: protocol for a systematic review and meta-analysis of observational studies

BACKGROUND

Suicide is a leading cause of death in children and youth, with suicidal thoughts and suicide attempts (referred to as non-fatal suicidal behaviors (NFSB)) being among its strongest predictors. Positive parenting (e.g., warmth, responsiveness), negative parenting (e.g., control, hostility), and parent-child relationship quality (e.g., trust, communication) have been reported to be associated with differences in NFSB in this population. To date, no comprehensive systematic review has considered together the wide range of parenting factors studied in relation to NFSB, and no meta-analysis of existing findings has been conducted. The present study will critically appraise and synthesize the existing evidence from observational studies that examine the relationships between parenting factors and (i) suicidal ideation and (ii) suicide attempt in children and youth.

METHODS

Studies will be retrieved from APA PsycInfo, MEDLINE, CINAHL, Embase, Scopus, and the Cochrane Library databases. Retrospective, cross-sectional, and longitudinal studies, conducted in clinical and population settings, among youth aged less than 25 years and published as articles and dissertations in English or French will be eligible. Two reviewers will select articles using the Covidence Software after title and abstract screening and full-text assessment, will extract information using double data entry, and will appraise studies' quality using the Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies. Any disagreements will be discussed with a third reviewer. Publication bias will be evaluated using funnel plots and Egger's test. In addition to a narrative summary of results, meta-analyses will be conducted using results from at least three studies. Three-level random effect models will allow to derive pooled estimates from dependent effect sizes (from the same sample or study). In case of significant heterogeneity, moderation analyses will be performed considering participants' characteristics and methodological aspects of studies. The results will be reported according to the PRISMA guidelines, and the certainty of evidence will be assessed using the GRADE approach.

DISCUSSION

In highlighting parenting factors associated with NFSB and in estimating the overall strength of these associations in children and youth, our results will inform further intervention and prevention strategies designed for young people experiencing NFSB and their families.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42020165345.

Contacts with primary and secondary healthcare prior to suicide: case-control whole-population-based study using person-level linked routine data in Wales, UK, 2000-2017

BACKGROUND

Longitudinal studies of patterns of healthcare contacts in those who die by suicide to identify those at risk are scarce.

AIMS

To examine type and timing of healthcare contacts in those who die by suicide.

METHOD

A population-based electronic case-control study of all who died by suicide in Wales, 2001-2017, linking individuals' electronic healthcare records from general practices, emergency departments and hospitals. We used conditional logistic regression to calculate odds ratios, adjusted for deprivation. We performed a retrospective continuous longitudinal analysis comparing cases' and controls' contacts with health services.

RESULTS

We matched 5130 cases with 25 650 controls (5 per case). A representative cohort of 1721 cases (8605 controls) were eligible for the fully linked analysis. In the week before their death, 31.4% of cases and 15.6% of controls contacted health services. The last point of contact was most commonly associated with mental health and most often occurred in general practices. In the month before their death, 16.6 and 13.0% of cases had an emergency department contact and a hospital admission respectively, compared with 5.5 and 4.2% of controls. At any week in the year before their death, cases were more likely to contact healthcare services than controls. Self-harm, mental health and substance misuse contacts were strongly linked with suicide risk, more so when they occurred in emergency departments or as emergency admissions.

CONCLUSIONS

Help-seeking occurs in those at risk of suicide and escalates in the weeks before their death. There is an opportunity to identify and intervene through these contacts.

Catalonia Suicide Risk Code Epidemiology (CSRC-Epi) study: protocol for a population-representative nested case-control study of suicide attempts in Catalonia, Spain

INTRODUCTION

Suicide attempts represent an important public health burden. Centralised electronic health record (EHR) systems have high potential to provide suicide attempt surveillance, to inform public health action aimed at reducing risk for suicide attempt in the population, and to provide data-driven clinical decision support for suicide risk assessment across healthcare settings. To exploit this potential, we designed the Catalonia Suicide Risk Code Epidemiology (CSRC-Epi) study. Using centralised EHR data from the entire public healthcare system of Catalonia, Spain, the CSRC-Epi study aims to estimate reliable suicide attempt incidence rates, identify suicide attempt risk factors and develop validated suicide attempt risk prediction tools.

METHODS AND ANALYSIS

The CSRC-Epi study is registry-based study, specifically, a two-stage exposure-enriched nested case-control study of suicide attempts during the period 2014-2019 in Catalonia, Spain. The primary study outcome consists of first and repeat attempts during the observation period. Cases will come from a case register linked to a suicide attempt surveillance programme, which offers in-depth psychiatric evaluations to all Catalan residents who present to clinical care with any suspected risk for suicide. Predictor variables will come from centralised EHR systems representing all relevant healthcare settings. The study's sampling frame will be constructed using population-representative administrative lists of Catalan residents. Inverse probability weights will restore representativeness of the original population. Analysis will include the calculation of age-standardised and sex-standardised suicide attempt incidence rates. Logistic regression will identify suicide attempt risk factors on the individual level (ie, relative risk) and the population level (ie, population attributable risk proportions). Machine learning techniques will be used to develop suicide attempt risk prediction tools.

ETHICS AND DISSEMINATION

This protocol is approved by the Parc de Salut Mar Clinical Research Ethics Committee (2017/7431/I). Dissemination will include peer-reviewed scientific publications, scientific reports for hospital and government authorities, and updated clinical guidelines.

TRIAL REGISTRATION NUMBER

NCT04235127.

Handgun Ownership and Suicide in California

BACKGROUND

Research has consistently identified firearm availability as a risk factor for suicide. However, existing studies are relatively small in scale, estimates vary widely, and no study appears to have tracked risks from commencement of firearm ownership.

METHODS

We identified handgun acquisitions and deaths in a cohort of 26.3 million male and female residents of California, 21 years old or older, who had not previously acquired handguns. Cohort members were followed for up to 12 years 2 months (from October 18, 2004, to December 31, 2016). We used survival analysis to estimate the relationship between handgun ownership and both all-cause mortality and suicide (by firearm and by other methods) among men and women. The analysis allowed the baseline hazard to vary according to neighborhood and was adjusted for age, race and ethnic group, and ownership of long guns (i.e., rifles or shotguns).

RESULTS

A total of 676,425 cohort members acquired one or more handguns, and 1,457,981 died; 17,894 died by suicide, of which 6691 were suicides by firearm. Rates of suicide by any method were higher among handgun owners, with an adjusted hazard ratio of 3.34 for all male owners as compared with male nonowners (95% confidence interval [CI], 3.13 to 3.56) and 7.16 for female owners as compared with female nonowners (95% CI, 6.22 to 8.24). These rates were driven by much higher rates of suicide by firearm among both male and female handgun owners, with a hazard ratio of 7.82 for men (95% CI, 7.26 to 8.43) and 35.15 for women (95% CI, 29.56 to 41.79). Handgun owners did not have higher rates of suicide by other methods or higher all-cause mortality. The risk of suicide by firearm among handgun owners peaked immediately after the first acquisition, but 52% of all suicides by firearm among handgun owners occurred more than 1 year after acquisition.

CONCLUSIONS

Handgun ownership is associated with a greatly elevated and enduring risk of suicide by firearm. (Funded by the Fund for a Safer Future and others.).