Mediators, moderators, and predictors of therapeutic change in cognitive-behavioral therapy for chronic pain

Although cognitive-behavioral therapies (CBT) have been demonstrated to be effective for a variety of chronic pain problems, patients vary in their response and little is known about patient characteristics that predict or moderate treatment effects. Furthermore, although cognitive-behavioral theory posits that changes in patient beliefs and coping mediate the effects of CBT on patient outcomes, little research has systematically tested this. Therefore, we examined mediators, moderators, and predictors of treatment effects in a randomized controlled trial of CBT for chronic temporomandibular disorder (TMD) pain. Pre- to post-treatment changes in pain beliefs (control over pain, disability, and pain signals harm), catastrophizing, and self-efficacy for managing pain mediated the effects of CBT on pain, activity interference, and jaw use limitations at one year. In individual mediator analyses, change in perceived pain control was the mediator that explained the greatest proportion of the total treatment effect on each outcome. Analyzing the mediators as a group, self-efficacy had unique mediating effects beyond those of control and the other mediators. Patients who reported more pain sites, depressive symptoms, non-specific physical problems, rumination, catastrophizing, and stress before treatment had higher activity interference at one year. The effects of CBT generally did not vary according to patient baseline characteristics, suggesting that all patients potentially may be helped by this therapy. The results provide further support for cognitive-behavioral models of chronic pain and point to the potential benefits of interventions to modify specific pain-related beliefs in CBT and in other health care encounters.