Comorbid PTSD and Depression Diagnoses Mediate the Association of Military Sexual Trauma and Suicide and Intentional Self-Inflicted Injury in VHA-Enrolled Iraq/Afghanistan Veterans, 2004-2014

Background: Exposure to military sexual trauma (MST) in veterans is associated with suicidal ideation. Previous research suggests there are mechanisms of this association, including posttraumatic stress disorder (PTSD) and depression. Research has yet to examine whether comorbid PTSD and depression mediate the association of MST and suicide and intentional self-inflicted injury, and whether this comorbidity confers a greater risk for suicide relative to PTSD-only and depression-only. The current study addressed this gap in our knowledge. Methods: Screening results identifying MST exposure, PTSD and depression diagnoses, suicide and intentional self-inflicted injury, and demographic covariates in 435,690 Iraq/Afghanistan veterans were extracted from Veterans Health Administration (VHA) medical records. Veterans were included if they attended VHA from 2004-2014. Mediation was tested with path analyses. Results: Suicide and intentional self-inflicted injury was observed in 16,149 (3.71%) veterans. The indirect effect of suicide and intentional self-inflicted injury, given a positive screen for MST, was highest among veterans with comorbid PTSD and depression diagnoses (indirect effect=3.18%, 95% confidence interval [CI] [3.01%, 3.32%]), with smaller probabilities observed for both PTSD-only (indirect effect=-0.18%, 95% CI [-0.20%, -0.14%]) and depression-only (indirect effect=0.56%, 95% CI [0.51%, 0.62%]; ps<.05). Limitations: Data were limited to VHA-enrolled Iraq/Afghanistan veterans. Conclusions: To reduce suicide risk among veterans with a history of MST, treatments may be most effective if they target comorbid PTSD and depression. Future research should examine the mechanisms through which comorbid PTSD and depression result in heightened risk for suicide and intentional self-inflicted injury.