The mediating role of acceptance in multidisciplinary cognitive behavioral therapy for chronic pain

Cognitive Behavioral Therapy (CBT) is the most frequently delivered psychological intervention for adults with chronic pain. The treatment yields modest effect sizes and the mechanisms of action remain understudied and unclear. Efforts are needed to identify treatment mediators that could be used to refine CBT and improve outcomes. The primary aim of this study is to investigate whether pain-related acceptance, from the psychological flexibility model, mediates changes in outcome over time in a CBT-based treatment program. This includes comparing how this variable relates to three other variables posited as potential mediators in standard CBT: life-control, affective distress, and social support. Participants attended a five-week outpatient multidisciplinary program with self-report data collected at assessment, post-treatment, and at 12-month follow-up. Multilevel structural equation modeling was used to test for mediation in relation to three outcomes: pain interference, pain intensity, and depression. Results indicate that effect sizes for the treatment were within the ranges reported in the CBT for pain literature. Pain-related acceptance was not related to pain intensity, which is in line with past empirical evidence and the treatment objectives in Acceptance and Commitment Therapy (ACT). Otherwise, pain-related acceptance was the strongest mediator across the different indices of outcome. Accumulating results like these suggest that acceptance of pain may be a general mechanism by which CBT-based treatments achieve improvements in functioning. More specific targeting of pain-related acceptance in treatment may lead to further improvements in outcome.