Exploring Pain-Severity and Psychological-Flexibility Trajectories During Group-Based Psychotherapy for Chronic Pain.

This study aimed to identify subgroups of patients sharing similar outcome trajectories during group-based psychotherapy for chronic pain, to explore baseline predictors of trajectories, and to describe clinical outcomes as a function of these trajectories. Participants (n = 71) underwent eight weekly sessions of group psychotherapy for chronic pain at a tertiary care multidisciplinary pain treatment center. Pain outcomes, psychological distress, sleep, pain acceptance, and psychological inflexibility were assessed before, during, directly after, and 3 months after the intervention. Using growth mixture modeling, three to four trajectories were identified for pain-severity and psychological-flexibility symptoms during treatment; baseline levels of depression, pain severity, and psychological flexibility predicted trajectory membership. More research is needed to better understand the mechanisms underlying patients' variability in trajectories of symptom change across treatment.