Acceptance and Commitment Therapy for Chronic Pain: Does Post-traumatic Stress Disorder Influence Treatment Outcomes?

Objective: The aim of this study was to determine whether post-traumatic stress disorder (PTSD) moderates treatment outcomes in Acceptance and Commitment Therapy for chronic pain. Design: Longitudinal. Setting: Veterans Affairs San Diego Healthcare System. Subjects: A total of 126 veterans with chronic pain participating in an Acceptance and Commitment Therapy intervention for chronic pain. A structured clinical interview was used at baseline to designate PTSD-positive (N = 43) and -negative groups (N = 83). Methods: Linear mixed-effects models to determine whether PTSD moderated change in pain interference, pain severity, pain acceptance, depressive symptoms, or pain-related anxiety at post-treatment and six-month follow-up. Results: Participants with co-occurring PTSD reported greater pain interference, pain severity, depressive symptoms, and pain-related anxiety at baseline. PTSD status did not moderate treatment effects post-treatment. Rather, there were significant improvements on all study measures across groups (P < 0.001). PTSD status moderated change in depressive symptoms at six-month follow-up (P < 0.05). Specifically, participants with chronic pain alone demonstrated improvement in depressive symptoms compared with pretreatment levels, whereas participants with PTSD regressed to pretreatment levels. Conclusions: PTSD status did not significantly affect treatment outcomes, with the exception of depressive symptoms at six-month follow-up. Overall, Acceptance and Commitment Therapy for chronic pain appears helpful for improving outcomes among veterans with co-occurring PTSD; however, veterans with co-occurring PTSD may experience fewer long-term gains compared with those with chronic pain alone.