Comparing duloxetine and pregabalin for treatment of pain and depression in women with fibromyalgia: an open-label randomized clinical trial

BackgroundDuloxetine and pregabalin are among the most widely used medications in the treatment of patients with fibromyalgia syndrome (FM).ObjectivesTo add to the very few lines of evidence that exist on the comparative safety and efficacy of these two medications.MethodsIn this open-label randomized clinical trial, outpatient women, who were diagnosed with FM based on American College of Rheumatology 2010 criteria, and had an age range of 18-65years old were assigned to either duloxetine 30-60mg or pregabalin 75-150mg per day for 4weeks. Patients were excluded in cases of having used duloxetine, pregabalin, gabapentin, or antidepressants within 12weeks prior to the study, having had a history of comorbid medical conditions that could provoke chronic pain, or having had comorbid neuropsychiatric disorders, except for major depressive/anxiety disorders. Primary outcomes were between-group differences in mean score changes from baseline to end point for Widespread Pain Index (WPI) and Beck Depression Inventory-II. Secondary outcomes were the same statistical estimates, but for Fibromyalgia Impact Questionnaire-Revised and 12-Item Short Form Survey. Descriptive statistics and independent samples t-test were the main methods of analysis. (www.irct.ir; IRCT2016030626935N1).ResultsAmong all the scales, only WPI scores improved with a statistically significant difference between the two treatment arms, favoring duloxetine (Mean difference in score change-2.32, 95% CI, -4.46 to-0.18; p=0.034; Cohen's d 0.53 95% CI, 0.04 to 1.02). Drop out rate and cumulative incidence of nausea was significantly higher in the duloxetine arm compared to the pregabalin arm.ConclusionThis study provides further evidence on higher efficacy of duloxetine compared to pregabalin for the treatment of pain in patients with fibromyalgia. Future comprehensive pragmatic clinical trials are warranted.