title: Time-varying associations of suicide with deployments, mental health conditions, and stressful life events among current and former US military personnel: a retrospective multivariate analysis.
abstract: BACKGROUND
  US military suicides have increased substantially 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 military service members.
  
  
  METHODS
  We did a retrospective multivariate analysis of all US military personnel between 2001 and 2011 (n=110 035 573 person-quarter-years, representing 3 795 823 service members). Outcome was death by suicide, either during service or post-separation. We used Cox proportional hazard models at the person-quarter level to examine associations of deployment, mental disorders, history of unlawful activity, stressful life events, and other demographic and service factors with death by suicide.
  
  
  RESULTS
  The strongest predictors of death by suicide were current and past diagnoses of self-inflicted injuries, major depression, bipolar disorder, substance use disorder, and other mental health conditions (compared with service members with no history of diagnoses, the hazard ratio [HR] ranged from 1·4 [95% CI 1·14-1·72] to 8·34 [6·71-10·37]). Compared with service members who were never deployed, hazard rates of suicide (which represent the probability of death by suicide in a specific quarter given that the individual was alive in the previous quarter) were lower among the currently deployed (HR 0·50, 95% CI 0·40-0·61) but significantly higher in the quarters following first deployment (HR 1·51 [1·17-1·96] if deployed in the previous three quarters; 1·14 [1·06-1·23] if deployed four or more quarters ago). The hazard rate of suicide increased within the first year of separation from the military (HR 2·49, 95% CI 2·12-2·91), and remained high for those who had separated from the military 6 or more years ago (HR 1·63, 1·45-1·82).
  
  
  CONCLUSIONS
  The increased hazard rate of death by suicide for military personnel varies by time since exposure to deployment, mental health diagnoses, and other stressful life events. Continued monitoring is especially needed for these high-risk individuals. Additional information should be gathered to address the persistently raised risk of suicide among service members after separation.
  
  
  BACKGROUND
  Partly funded by the Naval Research Program.
authors.affiliation: Naval Postgraduate School, Monterey, CA, USA; National Bureau of Economic Research, Cambridge, MA, USA. Electronic address: yshen@nps.edu.
authors.forename: Yu-Chu
authors.initials: YC
authors.lastname: Shen
authors.affiliation: Naval Postgraduate School, Monterey, CA, USA.
authors.forename: Jesse M
authors.initials: JM
authors.lastname: Cunha
authors.affiliation: Defense Health Agency, Falls Church, VA, USA.
authors.forename: Thomas V
authors.initials: TV
authors.lastname: Williams
mesh_terms: D006801:Humans; D008016:Life Change Events; D001523:Mental Disorders / Q000523:psychology*; D008889:Military Personnel / Q000523:psychology* / Q000706:statistics & numerical data; D015999:Multivariate Analysis; D012189:Retrospective Studies; D012307:Risk Factors; D013405:Suicide / Q000706:statistics & numerical data*; D013997:Time Factors; D014481:United States