Acceptance as a Mediator for Change in Acceptance and Commitment Therapy for Persons with Chronic Pain?

BACKGROUND: Cognitive behavior therapy (CBT) is considered effective for chronic pain, but little is known about active treatment components. Although acceptance correlates with better health outcomes in chronic pain patients, no study has examined its mediating effect in an experimental design. PURPOSE: The aim of the present study is to investigate acceptance as a mediator in acceptance and commitment therapy (ACT), a third wave CBT intervention, for chronic pain. METHOD: A bootstrapped cross product of coefficients approach was used on data from a previously published RCT evaluating ACT for chronic pain. To address the specificity of acceptance as a mediator, anxiety and depression were also tested as mediators. Outcome variables were satisfaction with life and physical functioning. Two change scores, pre-assessment to 6-month follow-up (n = 53) and pre-assessment to 12-month follow-up (n = 32), were used. RESULTS: Acceptance was found to mediate the effect of treatment on change in physical functioning from pre-assessment to follow-up at 6 months. Further, a trend was shown from pre-assessment to follow-up at 12 months. No indirect effect of treatment via acceptance was found for change in satisfaction with life. CONCLUSION: This study adds to a small but growing body of research using mediation analysis to investigate mediating factors in the treatment of chronic pain. In summary, the results suggest that acceptance may have a mediating effect on change in physical functioning in ACT for persons with chronic pain. However, given the small sample size of the study, these findings need to be replicated.