RESUMEN
BACKGROUND: Acceptance and Commitment Therapy (ACT) is a type of Cognitive Behavioural Therapy, which has demonstrated positive outcomes in individuals with chronic pain. The purpose of this study was to compare the effect of an 8-week programme combining Exercise with Acceptance and Commitment Therapy (ExACT) with a standalone supervised exercise programme at 1-year follow-up. METHODS: One hundred and seventy-five people with chronic pain were randomly assigned to ExACT or supervised exercise only. The primary outcome was pain interference measured with the Brief Pain Inventory-Interference Scale. Secondary and treatment process outcomes included pain severity, depression, anxiety, pain catastrophizing, pain self-efficacy, fear avoidance, pain acceptance, committed action, healthcare utilization, patient satisfaction, and global impression of change. Estimates of treatment effects at 1-year follow-up were based on intention-to-treat analyses, implemented using a linear mixed-effects model. RESULTS: Eighty-three participants (47.4%) returned the outcome measures at 1-year follow-up. No significant difference was observed between the groups for the primary outcome, pain interference. There was a statistically significant difference between the groups, in favour of ExACT for pain catastrophizing. Within group improvements that were observed within both groups at earlier timepoints were maintained at 1-year follow-up for many of the secondary and treatment process outcomes. ExACT group participants reported higher levels of satisfaction with treatment and global perceived change. CONCLUSIONS: The study results showed no significant difference between the two groups for the primary outcome pain interference at 1-year follow-up. Future research could investigate factors that may predict and optimize outcomes from these types of intervention for people living with chronic pain. SIGNIFICANCE: Few previous randomized controlled trials investigating ACT for chronic pain have included long-term follow-up. This study found that Exercise combined with ACT was not superior to supervised exercise alone for reducing pain interference at 1-year follow-up. Further research is necessary to identify key processes of therapeutic change and to explore how interventions may be modified to enhance clinical outcomes for people with chronic pain.