Effect of exposure-based vs traditional cognitive behavior therapy for fibromyalgia: a two-site single-blind randomized controlled trial

Fibromyalgia is a debilitating pain condition for which treatment effects are typically modest. The most evaluated psychological treatment is traditional cognitive behavior therapy (T-CBT), but promising effects have recently been seen in exposure-based cognitive behavior therapy (Exp-CBT). We investigated whether Exp-CBT was superior to T-CBT in a randomized controlled trial. Self-referred participants with fibromyalgia (N = 274) were randomized (1:1) to 10 weeks of Exp-CBT or T-CBT. Treatments were delivered online and presented as "CBT for fibromyalgia." Participants were assessed at baseline, weekly during treatment, posttreatment, and at 6- and 12-month follow-up. Primary outcome was the difference in reduction in fibromyalgia severity as measured using the Fibromyalgia Impact Questionnaire (FIQ) over 11 assessment points from baseline to posttreatment, modelled within an intention-to-treat framework using linear mixed effects models fitted on multiple imputed data. Approximately 91% of weekly FIQ scores were collected over the main phase. There was no significant difference between Exp-CBT and T-CBT in the mean reduction of fibromyalgia severity from pretreatment to posttreatment (b = 1.3, 95% CI -3.0 to 5.7, P = 0.544, d = -0.10). Minimal clinically important improvement was seen 60% in Exp-CBT vs 59% in T-CBT. Effects were sustained up to 12 months posttreatment. This well-powered randomized trial indicated that Exp-CBT was not superior to T-CBT for fibromyalgia. Both treatments were associated with a marked reduction in fibromyalgia severity, and the online treatment format might be of high clinical utility. T-CBT can still be regarded a reference standard treatment that remains clinically relevant when compared to novel treatment approaches.