An analysis of within-treatment change trajectories in valued activity in relation to treatment outcomes following interdisciplinary Acceptance and Commitment Therapy for adults with chronic pain.

A key issue in chronic pain treatment concerns changes necessary for reduced pain-related distress and disability. Acceptance and Commitment Therapy (ACT), a behavior change approach, theorizes several important treatment processes. Increased engagement in valued activities appears highly relevant as previous work has indicated it is related to current and future functioning and to treatment outcomes. This study sought to examine change trajectory in valued activity over the course of an interdisciplinary program of ACT and its relation to outcomes at treatment conclusion and three-month follow-up (N = 242). Latent change trajectories of valued activity were assessed weekly over four weeks of treatment and analyzed via latent growth curve and growth mixture modeling. A single latent trajectory with an increasing linear slope was indicated. Overall, slope of change in valued activity was predictive of improvement in psychosocial outcomes at post-treatment, including psychosocial disability, depression, pain anxiety, and discrepancy between values importance and success. Slope was not related to change in pain intensity or physical disability at post-treatment, nor was it related to change in any variable at follow-up. Findings are discussed in relation to the ACT model, in that support was provided in relation to post-treatment improvements for psychosocial variables.