Shared and Differential Psychological Processes Associated With Treatment Response in Mindful Self-Compassion and Cognitive-Behavioural Therapy for Chronic Pain: An Exploratory Secondary Analysis of a Randomized Controlled Trial

Background: Psychological treatments for chronic pain are effective, but the processes associated with therapeutic change, and whether these are shared across treatments or treatment-specific, remain unclear. This exploratory secondary analysis examined whether changes in pain acceptance, pain catastrophizing facets and self-compassion were associated with clinical outcomes in Mindful Self-Compassion (MSC) versus Cognitive-Behavioural Therapy (CBT). Methods: Data were drawn from a randomized trial comparing MSC (n = 61) and CBT (n = 59) in adults with chronic pain and elevated emotional distress. Processes and outcomes were assessed at baseline and post-treatment. Single and theoretically ordered multiple-mediator models examined whether changes in pain acceptance, rumination, magnification, helplessness and self-compassion were associated with changes in anxiety, depression, quality of life, pain interference and pain intensity. Results: Compared with CBT, MSC produced larger increases in pain acceptance and reductions in helplessness. These processes statistically accounted for improvements in self-compassion, depression, mental quality of life and pain interference; acceptance additionally accounted for reduced pain intensity, and helplessness for reduced anxiety. Rumination and magnification predicted improvements across treatments but did not explain between-group differences. Multiple-mediator models indicated that acceptance/self-compassion and helplessness/self-compassion pathways favoured MSC for depression, anxiety and mental quality of life, explaining up to 51% of change. No mediator accounted for physical quality of life. Conclusions: MSC and CBT appeared to engage overlapping processes, with differential associations mainly involving pain acceptance and helplessness. Acceptance may be more relevant to functional and pain-related outcomes, whereas helplessness/self-compassion pathways may be more relevant to emotional recovery. Significance Statement: This study identifies pain acceptance and reduced helplessness as candidate processes associated with treatment response in MSC and CBT, with acceptance more closely linked to pain-related and functional change and helplessness to emotional outcomes. These findings support more precise, process-based psychological treatment for chronic pain. © 2026 European Pain Federation - EFIC ®.