Risk of Suicide Attempt in US Army Infantry, Combat Engineer, and Combat Medic Soldiers

Introduction Understanding the relationship of military occupational specialties (MOSs) to suicide attempt (SA) among US Army soldiers, and the patterns of these associations over time, can identify periods of increased risk and inform prevention and treatment efforts. The current study aimed to identify SA risk and sociodemographic and service-related risk factors for SA among infantry, combat engineers, and combat medics, soldiers identified in previous research to have elevated suicidal behavior rates relative to soldiers in other MOSs. This examination also builds on previous work (2004-2009) by including women, who were integrated into previously closed combat arms billets in 2016. Materials and Methods This longitudinal, retrospective case-control study of administrative person-month records from Regular Army enlisted soldiers on active duty from 2016 through 2019 identified all first SAs (n=1,393 person-months) among only soldiers in each of 3 MOS categories (infantry, combat engineer, combat medic), stratifying soldiers in these mutually exclusive MOS groups. Our study also included independent equal-probability control subsamples for each of the 3 groups, totaling 17,317 control person-months. Logistic regression models examined sociodemographic and service-related time-varying risk factors of SA among each of the MOS groups. Discrete-time survival models with person-month as the unit of analysis estimated MOS-specific SA risk by time in service. Analysis of the deidentified data was approved by Institutional Review Boards of the Uniformed Services University of the Health Sciences, University of Michigan Institute for Social Research, University of California San Diego, and Harvard Medical School. Results The sample was primarily male (94.3%), White (66.1%), and in their first 4 years of service (65.6%). In all, 813 infantry soldiers (yearly rate: 353.1/100,000 soldiers), 214 combat engineers (rate: 566.3/100,000), and 366 combat medics (rate: 524.2/100,000) attempted suicide. In separate multivariable models, odds of SA in all 3 MOSs were higher among soldiers who were women, had less than a high school education, and had less time in service, with those who had less than 1 year of service at particularly elevated risk. Among infantry and combat medics, SA risk was higher among those who had never deployed. Timing of greatest SA risk during the first year of service differed by MOS: months 9-12 among infantry; months 1-3 among combat engineers; and months 6-9 among combat medics. SA rates among combat medics remained uniquely elevated over the first 4 years of service. Conclusions Risk factors for SA were similar across the 3 MOS categories. However, the timing of highest risk in the first year differed by MOS. Findings highlight the importance of MOS-specific risk factors and timing in identifying important stressors and targeting interventions.