Duloxetine for pain in fibromyalgia in adults: a systematic review and a meta-analysis

Objectives: The objective of this systematic review was to assess the analgesic efficacy of duloxetine (DLX) for fibromyalgia (FM) and find out which dosage between 60 mg/d DLX and 120 mg/d DLX was more suitable for clinical application. Methods: A systematic search through multiple databases (Cochrane Central Register of Controlled Trials (CENTRAL), ProQuest, PubMed) was conducted from 2000 until 7 March 2019. All steps were performed by two or more independent reviewers. The meta-analysis was performed to report the effects of DLX on pain reduction and its accompanied adverse events. Results: This meta-analysis, including seven studies with 2642 FM patients, demonstrated that DLX could produce greater pain relief in FM than placebo (standardized mean difference (SMD) -0.26; 95% confidence interval (CI) -0.37 to -0.16). The risk ratio (RR) of at least 30% pain relief was 1.31 (95% CI 1.19 to 1.44); the RR of at least 50% pain relief was 1.46 (95% CI 1.28 to 1.67). However, the patients with DLX who suffered adverse events were more common than the ones with placebo (RR 1.17, 95% CI 1.12 to 1.23). The withdrawal effect included adverse event withdrawal and lack of efficacy withdrawal. The subgroup analyses of withdrawal effects demonstrated that 120 mg/d DLX had a higher incidence (RR 0.96, 95% CI 0.80 to 1.15) than 60 mg/d DLX (RR 0.77, 95% CI 0.63 to 0.93). Conclusions: In general, DLX was a great choice for pain relief in FM. Moreover, 60 mg/d DLX produced less withdrawal effects than 120 mg/d DLX.