Integrated Exposure-Based Therapy for Co-Occurring Post Traumatic Stress Disorder (PTSD) and Substance Dependence: Predictors of Change in PTSD Symptom Severity

This paper examines factors associated with change in PTSD symptom severity among individuals randomised to receive an integrated exposure-based psychotherapy for PTSD and substance dependence–Concurrent Treatment of PTSD and Substance Use Disorders Using Prolonged Exposure (COPE). Outcomes examined include change in PTSD symptom severity as measured by the Clinician Administered PTSD Scale (CAPS), and the reliability and clinical significance of change in PTSD symptom severity. Factors examined include patient baseline characteristics, treatment characteristics, and events over follow-up. The mean difference in CAPS score was 38.24 (SE 4.81). Approximately half (49.1%) demonstrated a reliable and clinically significant improvement in PTSD symptom severity. No one was classified as having demonstrated clinically significant worsening of symptoms. Three independent predictors of reductions in PTSD symptom severity were identified: baseline PTSD symptom severity (β 0.77, SE 0.23, p = 0.001), number of traumas experienced prior to baseline (β −0.30, SE 0.15, p = 0.049), and number of sessions attended (β 2.05, SE 0.87, p = 0.024). The present study provides further evidence regarding the safety of the COPE treatment and factors associated with improvement in PTSD symptom severity. The identification of only a small number of predictors of the outcome points to the broad applicability of the COPE treatment to PTSD and substance use disorder (SUD) patients.