There is no consensus over the effect size of cognitive behavioral therapy (CBT) in the treatment of fibromyalgia (FM). This study aims to evaluate the effect of CBT on FM patients, through assessing circulating proinflammatory cytokines.
A controlled, single-blind, parallel clinical trial was performed with 21 FM patients in each group. Sixteen FM patients in the intervention group (CBT) and 17 FM patients in the control group (waiting-list) completed the study. For the intervention group, traditional face-to-face CBT was performed for groups of 10 and 11 patients in 20 sessions. Fibromyalgia Impact Questionnaire (FIQ), widespread pain index (WPI), circulating IL-6, IL-8, and TNF-α level were evaluated before and after the intervention using enzyme-linked immunosorbent assay. Intention-to-treat analysis was performed as the primary analysis.
The average changes of factors examined were as follows: FIQ score -0.61 ± 5.5 in the waiting-list group and 10.2 ± 14.9 in the CBT group (p = 0.012); WPI -0.33 ± 1.1 in the waiting-list group and 2.4 ± 3.1 in the CBT group (p = 0.002); serum IL-6 level -0.05 ± 0.86 pg/ml in the waiting-list group and 1.5 ± 2.4 pg/ml in the CBT group (p = 0.002); serum IL-8 level - 0.55 ± 0.2.5 pg/ml in the waiting-list group and 5 ± 5.9 pg/ml in the CBT group (p = 0.002); serum TNF-α level 0.67 ± 1.8 pg/ml in the waiting-list group and 0.7 ± 1.6 pg/ml in the CBT group (p = 0.89).
Reductions in proinflammatory cytokines after CBT compared with a waiting-list control group confirm the potential value of these biomarkers as surrogate outcome measures in FM.