Abstract
OBJECTIVE: This study aimed to compare suicide mortality rates for patients receiving two evidence-based psychotherapy (EBP) protocols for posttraumatic stress disorder (PTSD): cognitive processing therapy (CPT) and prolonged exposure (PE). METHODS: Suicide mortality was measured among U.S. Department of Veterans Affairs patients with PTSD who received EBP from 2009 through 2019. Regional variation in delivering CPT versus PE was leveraged as an instrumental variable (IV) to compare suicide mortality by using standard adjustment and IV-based analyses. RESULTS: In total, 62,686 patients received EBP for PTSD; 82.4% were male, and the mean±SD age was 46.9±14.4. Patients were followed for a median of 6 years, and there were 136 deaths by suicide (38.3 and 32.4 per 100,000 person-years among the CPT and PE groups, respectively). The regional rate of CPT versus PE delivery was a strong IV that had greater explanatory power for the type of EBP received than all patient factors combined. The standard adjustment model for CPT produced a hazard ratio of 1.25, whereas the reduced-form IV produced a hazard ratio of 1.22. The probit IV, in which relevant covariates were updated annually, produced an odds ratio of 0.99. The time-to-event IV produced a hazard ratio of 1.20. The differences were not significant. CONCLUSIONS: No statistically significant difference was found between CPT and PE in the outcome of death by suicide. More effective interventions that result in higher remission rates would likely need to be developed to achieve a relative decrease in suicide risk through PTSD treatment.