Risk of Suicide Among US Military Service Members Following Operation Enduring Freedom or Operation Iraqi Freedom Deployment and Separation From the US Military.

Importance: A pressing question in military suicide prevention research is whether deployment in support of Operation Enduring Freedom or Operation Iraqi Freedom relates to suicide risk. Prior smaller studies report differing results and often have not included suicides that occurred after separation from military service.

Objective: To examine the association between deployment and suicide among all 3.9 million US military personnel who served during Operation Enduring Freedom or Operation Iraqi Freedom, including suicides that occurred after separation.

Design, Setting, and Participants: This retrospective cohort design used administrative data to identify dates of deployment for all service members (October 7, 2001, to December 31, 2007) and suicide data (October 7, 2001, to December 31, 2009) to estimate rates of suicide-specific mortality. Hazard ratios were estimated from time-dependent Cox proportional hazards regression models to compare deployed service members with those who did not deploy.

Main Outcomes and Measures: Suicide mortality from the Department of Defense Medical Mortality Registry and the National Death Index.

Results: Deployment was not associated with the rate of suicide (hazard ratio, 0.96; 99% CI, 0.87-1.05). There was an increased rate of suicide associated with separation from military service (hazard ratio, 1.63; 99% CI, 1.50-1.77), regardless of whether service members had deployed or not. Rates of suicide were also elevated for service members who separated with less than 4 years of military service or who did not separate with an honorable discharge.

Conclusions and Relevance: Findings do not support an association between deployment and suicide mortality in this cohort. Early military separation (<4 years) and discharge that is not honorable were suicide risk factors.