Associations of time-related deployment variables with risk of suicide attempt among soldiers: Results from the army study to assess risk and resilience in servicemembers (Army STARRS)

IMPORTANCE There has been limited systematic examination of whether risk of suicide attempt (SA) among US Army soldiers is associated with time-related deployment variables, such as time in service before first deployment, duration of first deployment, and dwell time (DT) (ie, length of time between deployments). OBJECTIVE To examine the associations of time-related deployment variables with subsequent SA among soldiers who had deployed twice. DESIGN, SETTING, AND PARTICIPANTS Using administrative data from January 1, 2004, through December 31, 2009, this longitudinal, retrospective cohort study identified person-month records of active-duty Regular Army enlisted soldiers who had served continuously in the US Army for at least 2 years and deployed exactly twice. The dates of analysis were March 1 to December 1, 2017. There were 593 soldiers with a medically documented SA during or after their second deployment. An equal-probability sample of control person-months was selected from other soldiers with exactly 2 deployments (n = 19 034). Logistic regression analyses examined the associations of time in service before first deployment, duration of first deployment, and DT with subsequent SA. MAIN OUTCOMES AND MEASURES Suicide attempts during or after second deployment were identified using US Department of Defense Suicide Event Report records and International Classification of Diseases, Ninth Revision, Clinical Modification E950 to E958 diagnostic codes. Independent variables were constructed from US Army personnel records. RESULTS Among 593 SA cases, most were male (513 [86.5%]), white non-Hispanic (392 [66.1%]), at least high school educated (477 [80.4%]), currently married (398 [67.1%]), and younger than 21 years when they entered the US Army (384 [64.8%]). In multivariable models adjusting for sociodemographics, service-related characteristics, and previous mental health diagnosis, odds of SA during or after second deployment were higher among soldiers whose first deployment occurred within the first 12 months of service vs after 12 months (odds ratio, 2.0; 95% CI, 1.6-2.4) and among those with a DT of 6 months or less vs longer than 6 months (odds ratio, 1.6; 95% CI, 1.2-2.0). Duration of first deployment was not associated with subsequent SA. Analysis of 2-way interactions indicated that the associations of early deployment and DT with SA risk were not modified by other characteristics. Multivariable population-attributable risk proportions were 14.2% for deployment within the first 12 months of service and 4.0% for DT of 6 months or less.