Key Points

Question What are the sex-specific risk profiles for death from suicide in a general population sample?

Findings In this case-cohort study of 14 103 individuals who died by suicide, risk profiles for suicide were different among men and women in a general population sample of 265 183 persons who did not die by suicide, with physical health more important to men’s than women’s suicide risk. Results suggest psychotropic medications and psychiatric disorders are important to suicide risk and, for many diagnostic variables and prescriptions, a longer vs shorter period of observation (eg, 48 vs 6 months prior to suicide) appeared to be more important.

Meaning These findings suggest consistency with what is known about suicide risk but also potentially important, and understudied risk factors with evidence of unique suicide risk profiles among specific subpopulations.

Abstract

Importance Suicide is a public health problem, with multiple causes that are poorly understood. The increased focus on combining health care data with machine-learning approaches in psychiatry may help advance the understanding of suicide risk.

Objective To examine sex-specific risk profiles for death from suicide using machine-learning methods and data from the population of Denmark.

Design, Setting, and Participants A case-cohort study nested within 8 national Danish health and social registries was conducted from January 1, 1995, through December 31, 2015. The source population was all persons born or residing in Denmark as of January 1, 1995. Data were analyzed from November 5, 2018, through May 13, 2019.

Exposures Exposures included 1339 variables spanning domains of suicide risk factors.

Main Outcomes and Measures Death from suicide from the Danish cause of death registry.

Results A total of 14 103 individuals died by suicide between 1995 and 2015 (10 152 men [72.0%]; mean [SD] age, 43.5 [18.8] years and 3951 women [28.0%]; age, 47.6 [18.8] years). The comparison subcohort was a 5% random sample (n = 265 183) of living individuals in Denmark on January 1, 1995 (130 591 men [49.2%]; age, 37.4 [21.8] years and 134 592 women [50.8%]; age, 39.9 [23.4] years). With use of classification trees and random forests, sex-specific differences were noted in risk for suicide, with physical health more important to men’s suicide risk than women’s suicide risk. Psychiatric disorders and possibly associated medications were important to suicide risk, with specific results that may increase clarity in the literature. Generally, diagnoses and medications measured 48 months before suicide were more important indicators of suicide risk than when measured 6 months earlier. Individuals in the top 5% of predicted suicide risk appeared to account for 32.0% of all suicide cases in men and 53.4% of all cases in women.

Conclusions and Relevance Despite decades of research on suicide risk factors, understanding of suicide remains poor. In this study, the first to date to develop risk profiles for suicide based on data from a full population, apparent consistency with what is known about suicide risk was noted, as well as potentially important, understudied risk factors with evidence of unique suicide risk profiles among specific subpopulations.