Predictors and mediators of outcome in cognitive behavioral therapy for chronic pain: the contributions of psychological flexibility.

There is now a consensus in the literature that future improvements in outcomes obtained from cognitive behavioral therapy (CBT) for chronic pain will require research to identify patient and treatment variables that help explain outcomes. The first aim of this study was to assess whether pre-treatment scores on measures of psychological (in)flexibility, acceptance, committed action, cognitive (de)fusion, and values-based action predict outcomes in a multidisciplinary, multicomponent, group-based CBT program for adults with chronic pain. The second aim was to assess whether change scores on these same measures mediate outcomes in the treatment program. Participants were 232 people attending treatment for chronic pain. Of the psychological flexibility measures, only pre-treatment scores on the psychological inflexibility scale predicted outcomes; higher scores on this measure were associated with worse outcomes. However, change scores on each of the psychological flexibility measures separately mediated outcomes. The efficacy of CBT for chronic pain may be improved with a greater focus on methods that increase psychological flexibility.