No effect of approved fibromyalgia drugs on the social pain (invalidation) contrary to physical pain: an open-label short-term randomized clinical trial.

Abstract

The social pain or invalidation denoting painful feeling following social conflicts or misunderstanding about illness legitimacy has been proposed as a salient disabling symptom besides physical pain or non-pain symptoms in fibromyalgia (FM). We sought to evaluate the effect of 1-month administration of duloxetine or pregabalin on the invalidation dimensions in FM patients with respect to the comparison of these two drugs on this issue. This open-label randomized clinical trial study was performed on FM patients whose diagnoses were confirmed by a rheumatologist based on the 2016 American College of Rheumatology (ACR). Primary outcome measure (Illness Invalidation Inventory (3*I)) and secondary outcome measures (Beck Depression Inventory-II (BDI-II), widespread pain index (WPI), and polysymptomatic distress scale (PSD)) were compared before and after treatment, using paired t test or Wilcoxon signed test. Of 81 eligible FM patients, 44 patients in the duloxetine arm and 27 patients in the pregabalin arm completed the study protocol. Overall, no significant improvement was seen in 3*I scores after treatment with either duloxetine or pregabalin, except in the lack of understanding of medical professionals which improved after treatment with pregabalin (2.43 ± 1.38 to 1.79 ± 0.94, p value: 0.01). There were no intragroup and intergroup differences in the effects of duloxetine and pregabalin on 3*I scores when adjusted with the cofounders. Both duloxetine and pregabalin improved WPI, BDI-II, and PSD scores significantly. Short-term FM pharmacological treatment had no effect on social pain. This finding was regardless of drug type, improvement of physical pain, and depression.