Objective
Soldiers’ mental health is adversely affected by the death and injury of other unit members, but it is not known if risk of suicide attempt is influenced by previous suicide attempts in one’s unit.
Method
Using administrative data from the Army Study to Assess Risk and Resilience in Servicemembers (Army STARRS), we identified person-month records for all active duty Regular Army enlisted soldiers who attempted suicide from 2004–2009 (n=9,650) and an equal-probability sample of control person-months (n=153,528). Logistic regression analyses examined the number of past-year suicide attempts in one’s unit as a predictor of subsequent suicide attempt, controlling for socio-demographics, service-related characteristics, prior mental health diagnosis, and other unit variables, including suicide-, combat-, and accident-related unit deaths. We also examined whether the influence of previous unit suicide attempts varied by military occupational specialty (MOS) and unit size.
Results
In adjusted models, soldiers were more likely to attempt suicide if one or more suicide attempts occurred in their unit during the past year (OR=1.4–2.3; p<0.001), with odds increasing as the number of unit attempts increased. The odds of suicide attempt among soldiers in a unit with five or more past-year attempts was more than twice that of soldiers in a unit with no previous attempts (OR=2.3; 95% CI=2.1–2.6). The association of previous unit suicide attempts with subsequent risk was significant whether soldiers had a combat arms MOS or other MOS (OR=1.4–2.3; p<0.001). It was also significant regardless of unit size, with the highest risk for those in smaller units (1–40 soldiers) (OR=2.1–5.9; p<0.001). The population-attributable risk proportion for one or more unit suicide attempts in the past year indicated that if this risk could be reduced to no unit attempts, 18.2% of attempts would not occur.
Conclusions
Soldiers’ risk of suicide attempt increased as the number of past-year suicide attempts within their unit increased. This was true for both combat arms and other MOSs, and for units of any size, but particularly for smaller units. Units with a history of suicide attempts may be important targets for preventive interventions.