Outcome Expectancy for Prolonged Exposure Therapy Predicts Symptom Improvement in Veterans with Post-Traumatic Stress Disorder

Objective: This study explores outcome expectancies – how much a patient believes a therapy will result in improvement – as a predictor of outcome of prolonged exposure therapy (PE) in veterans with PTSD.

Methods: Prior to PE therapy, veterans were administered a PTSD treatment expectations (PTE) survey consisting of three 11-point Likert scale questions with possible scores of 0-30. The primary outcome was changes in total PTSD Checklist for DSM-5 (PCL-5) scores before and after PE therapy. ANOVA in repeated measures was used to evaluate the association between PTE tertiles and PTSD symptom changes.

Results: 57 veterans consented and 35 (61.4%) completed therapy. Mean differences in PCL-5 scores pre-/post-PE were 19.0, 14.4, and 31.1 (p<0.0006 for all) in the low (0-12), middle (13-20) and high (21-30) PTE tertiles, respectively.

Conclusions: Consistent with current literature, our study shows that PTSD outcome expectancy may be useful in predicting treatment response to PE.