Time-varying associations of suicide with deployments, mental health conditions, and stressful life events among current and former US military personnel

Abstract

Background U.S. military suicides have increased significantly over the past decade and currently account for almost 20% of all military deaths. We investigated the associations of a comprehensive set of time-varying risk factors with suicides among current and former service members. Methods Retrospective multivariate analysis of all U.S. military personnel between 2001-2011 (N=110,035,573 person-quarters, representing 3,795,823 service members). Outcome was death by suicide, either during service or post-separation. Cox proportional hazard models at the person-quarter level were used to examine associations of deployment, mental disorders, history of unlawful activity, stressful life events, and other demographic and service factors with suicide death. Findings The strongest predictors of suicide were current and past diagnoses of self-inflicted injuries, major depression, bipolar disorder, substance use disorder, and other mental health conditions (comparing to those with no history of diagnoses, hazard ratio, HR, ranged from 1.4 [CI, 1.14- 1.72] to 8.34 [CI, 6.71-10.37]). Compared to those never deployed, hazards were lower among the currently-deployed (HR=0.50; CI,0.40-0.61) but significantly higher in the quarters following first deployment (HR=1.51; CI, 1.17-1.96). Hazard of suicide was elevated within the first year of separation from the military (HR=2.49; CI,2.12-2.91), and remained high for those who separated 6 or more years ago (HR=1.63; CI,1.45-1.82). Interpretation Elevated hazard of suicide death varies by time-since-exposure to deployment, mental health diagnoses, and other stressful life events. Continued monitoring is particularly needed for these high-risk individuals. Additional information should be gathered to address the persistent elevated risks of suicides among service members after separation.