A systematic review and meta-analysis of the effect of deployment and combat exposures on suicide attempts and deaths

Purpose: The past 16 years has produced a considerable body of research on the potential effect of deployment and combat exposures on suicide attempts and deaths. However, overall results are inconsistent. We conducted a systematic review and meta-analysis to integrate and evaluate this literature. Methods: We searched PubMed, PsycINFO, CINAHL, and EMBASE from database inception to January 2025 for case-control and cohort study designs that aligned with our criteria. Of the 1968 records reviewed, we identified 26 relevant full-text articles. Results: Seven studies on deployment and suicide deaths were sufficiently independent to submit to meta-analysis. The omnibus risk ratio estimate was 0.93 (95 % CI = 0.83, 1.04; τ² = 0.016; I² = 92.74 %). Risk of bias across the studies was high to very high because of uncontrolled confounding and selection. There was little direct evidence of an association between combat exposure and suicide attempts and deaths. Design heterogeneity in the exposure definition precluded a meta-analysis. Risk of bias for these studies was high to very high for the same issues as the deployment studies in addition to self-report or proxy measures of exposure. Conclusions: There is very little evidence of an increase in suicide mortality risk associated with deployment. Several studies reported a protective effect which may be attributed to selection and immortal-time biases. We could not draw any inference on combat exposure and suicide risk. Future research should improve the assessment of combat exposure and begin time at risk at the time of exposure.