Effectiveness of group acceptance and commitment therapy for fibromyalgia: A 6-month randomized controlled trial (EFFIGACT study)

In the last decade, there has been burgeoning interest in the effectiveness of third-generation psycholog-ical therapies for managing fibromyalgia (FM) symptoms. The present study examined the effectivenessof acceptance and commitment therapy (ACT) on functional status as well as the role of pain acceptanceas a mediator of treatment outcomes in FM patients. A total of 156 patients with FM were enrolled atprimary health care centers in Zaragoza, Spain. The patients were randomly assigned to a group-basedform of ACT (GACT), recommended pharmacological treatment (RPT; pregabalin + duloxetine), or wait list(WL). The primary end point was functional status (measured with the Fibromyalgia Impact Question-naire, FIQ). Secondary end points included pain catastrophizing, pain acceptance, pain, anxiety, depres-sion, and health-related quality of life. The differences between groups were calculated by linearmixed-effects (intention-to-treat approach) and mediational models through path analyses. Overall,GACT was statistically superior to both RPT and WL immediately after treatment, and improvementswere maintained at 6 months with medium effect sizes in most cases. Immediately after treatment,the number needed to treat for 20% improvement compared to RPT was 2 (95% confidence interval1.2–2.0), for 50% improvement 46, and for achieving a status of no worse than mild impaired function(FIQ total score <39) also 46. Unexpectedly, 4 of the 5 tested path analyses did not show a mediationeffect. Changes in pain acceptance only mediated the relationship between study condition andhealth-related quality of life. These findings are discussed in relation to previous psychological researchon FM treatment.