Understanding the Role of Therapist Quality in Accounting for Heterogeneity of Patient Outcomes in Psychosocial Chronic Pain Treatments.

A variety of evidence-based psychosocial treatments now exist for chronic pain. However, on average, effect sizes have tended to be modest and there is a high degree of heterogeneity in treatment response. In this focus article, we explore the potential role that therapist quality in delivering treatment may have in accounting for a degree of this variability in outcome. Therapist quality refers to the skillful delivery of treatment, harnessing both specific and common therapeutic factors during sessions. While recognized as important to assess and report in clinical trials by some reporting guidelines, few randomized controlled trials evaluating psychosocial treatments for chronic pain have reported on therapist factors. We reviewed the clinical trials included in three systematic reviews and meta-analyses of trials of cognitive-behavioral therapy (mainly), mindfulness-based interventions, and acceptance and commitment therapy. We found that of the 134 trials included, only nine assessed and reported therapist quality indicators, with a variety of procedures used. This is concerning as without knowledge of the quality in which treatments are delivered, the estimates of effect sizes reported may be misrepresented. We contextualize this finding by drawing on the broader psychotherapy literature which has shown that more skillful, effective therapists demonstrated ten times better patient response rates. Examination of the characteristics associated with these more effective therapists tends to indicate that skillful engagement of common factors in therapy sessions represents a distinguishing feature. We conclude by providing recommendations for assessing and reporting on therapist quality within clinical trials evaluating psychosocial treatments for chronic pain. PERSPECTIVE: Therapist quality in the delivery of psychosocial treatments for chronic pain has rarely been assessed in clinical trials. We propose that therapist quality indicators are an under-studied mechanism that potentially contributes to the heterogeneity of treatment outcomes. We provide recommendations for assessing and reporting on therapist quality in future trials.