The Effect of Cognitive-Behavioral Therapy Versus Duloxetine on the Laboratory Indices of Inflammation in Fibromyalgia: A Randomized Controlled Trial

Proinflammatory cytokines have been introduced as surrogate markers of inflammation in fibromyalgia (FM). In this study, we aimed to evaluate the effect of cognitive-behavioral therapy (CBT) versus duloxetine on the serum levels of candidate cytokines, besides their impact on the clinical outcome measures. A total of 128 patients were randomized to either CBT or duloxetine group, 64 patients each. For the CBT group, traditional face-to-face CBT was offered in twice-weekly sessions over ten weeks. For the duloxetine group, the treatment was started with 30 mg/day duloxetine and continued with 60 mg/day duloxetine after a week, up to 10 weeks. The primary outcome measures were the serum levels of IL-6, IL-8, and TNFα. Secondary outcome measures were the fibromyalgia impact questionnaire (FIQ) and the widespread pain index (WPI). Fifty-two patients in the CBT group and 53 patients in the duloxetine group completed the study. No significant difference was observed between the baseline characteristics of the two study groups. All the outcome measures were significantly improved after the intervention in both study groups. No significant difference was observed between the two study groups regarding the mean change of IL-6, IL-8, TNFα, FIQ, and WPI (p = 0.43, p = 0.85, p = 0.91, p = 0.8, and p = 0.67, respectively, Intention-to-treat analysis). Therefore, CBT can be selected as an alternative for duloxetine in the treatment of FM symptoms, particularly in patients with duloxetine intolerance. However, patients’ motivation should be taken into account before selecting CBT as the treatment of choice.