Duloxetine for fibromyalgia syndrome: a systematic review and meta-analysis

INTRODUCTION: The optimal dose of duloxetine in the management of fibromyalgia remains still controversial. Therefore, a systematic review and meta-analysis to investigate efficacy and safety of duloxetine was conducted. The outcomes of interests were to assess changes in Fibromyalgia Impact Questionnaire (FIQ), Brief Pain Inventory (BPI), and Clinical Global Impression (CGI). The rate of of adverse events and those leading to therapy discontinuation were also investigated. MATERIAL AND METHODS: This study followed the 2020 PRISMA guidelines. The literature search started in December 2022 accessing PubMed, Google scholar, Embase, and Scopus databases. All the RCTs investigating the efficacy and safety of daily administration of duloxetine for fibromyalgia were accessed. Studies reporting quantitative data under the outcomes of interest, and including a minimum of 10 patients who completed a minimum of 4 weeks follow-up, were included. Studies on combined pharmacological and non-pharmacological managements for fibromyalgia were not considered. RESULTS: Data from 3432 patients (11 RCTs) were included. The mean age of the patients was 46.4 ± 10.7 years old, and the mean BMI 25.3 ± 3.2 kg/m(2). 90% (3089 of 3432 patients) were women. The 60 mg/daily cohort reported the higher FIQ, followed by the 30, 30–60, 120 mg/daily, and placebo groups, while the 60–120 mg /daily group performed the worst results. Concerning the CGI severity scale, placebo resulted in the lowest improvement, and no differences were found in the other groups. Concerning the BPI interference and severity pain scores, the 30–60 mg/daily group reported the worst result, along with the placebo group. The rate of adverse events leading to study discontinuation were lower in the 60–120 group, followed by the 30–60 and 30 mag/daily groups. Duloxetine was superior in all the comparisons to placebo, irrespective of the doses, in all endpoints analysed. CONCLUSIONS: Duloxetine could help in improving symptoms of fibromyalgia. The dose of duloxetine should be customised according to individual patients. Irrespective of the doses, duloxetine was more effective than placebo in the management of fibromyalgia. The dose of duloxetine must be customised according to individual patients. Level of evidence I Meta-analysis of double-blind RCTs.