How therapist effects shape pain-related outcome improvement in psychological treatments for chronic pain.

Psychological chronic pain treatments have variable efficacy across individual patients, and on average tend to produce modest effects. In order to improve treatment outcomes, the past decade has seen a rapid increase in research focused on determining the mechanisms underlying treatment-related gains. The near exclusive focus of this research has been on uncovering patient-related mediators and moderators. However, treatment is delivered within the context of a patient-therapist dyad, and the dynamic contribution of therapist-related factors in influencing this dyad and patient outcomes has remained largely unexamined. The purpose of the current paper is to consider the unique contributions of therapist-related factors within our proposed "Top 3" dynamic, candidate contextual mechanisms: therapeutic working alliance, group climate/cohesion (i.e., in group therapy), and therapist quality. We define these process variables, identify validated measures, and review research documenting their effects on outcomes, drawing from the pain and broader psychotherapy literature. It is well established that some therapists are more effective than others, with so-called exceptional (i.e., not merely competent) therapists shown to produce effect sizes twice as large and demonstrate up to ten times better patient response rates. We focus on identifying the behaviors that such exceptional therapists engage in to harness the working alliance, build and maintain group cohesion and skilfully deliver and train patients in various therapeutic techniques. Future pain treatment outcome research evaluating the role of therapists in these "Top 3" process variables has the potential to provide novel insights into treatment mechanisms, inform therapist training, and to advance precision medicine.