How and for whom does a positive affect intervention work in fibromyalgia: An analysis of mediators and moderators.

Objectives: Psychological interventions designed to enhance positive affect are promising ways to promote adaptive functioning in people with chronic pain. However, few studies have addressed the efficacy of positive affect interventions in chronic pain populations and examined which patients can benefit more from them. The aim of the present study was to identify mediators and moderators of the best possible self intervention (BPS) in fibromyalgia patients.Methods: We used data from a previous randomized controlled trial that examined changes in pain interference, depression, self‐efficacy and quality of life after the BPS intervention.Results: Mediation analyses showed that depression mediated changes in pain in-terference. Positive and negative affect were significant mediators of the change in depression and quality of life. No significant mediators of the change in self‐efficacy were found. Baseline levels of quality of life, emotion regulation strategies of nega-tive and positive affect, and rumination moderated the effects of the intervention on depressive symptomatology.Discussion: In fibromyalgia patients, the effects of the BPS on the outcomes seem to be more related to changes in affect than to changes in future expectations.Significance: This study presents evidence about who can benefit from an interven-tion designed to augment positive affect and promote positive functioning in FMS patients and how these changes occur. It extends previous findings on patient charac-teristics associated with the response to pain management interventions