Effectiveness of pharmacological therapies for fibromyalgia syndrome in adults: an overview of Cochrane Reviews

OBJECTIVES: To summarize and evaluate Cochrane reviews of pharmacological therapies for adults with fibromyalgia syndrome (FMS) pain. METHODS: Systematic search of Cochrane Database of Systematic Reviews to May 2024. Generic quality assessment used AMSTAR-2 criteria, validity checks of potentially critical factors in evaluation of analgesic efficacy and assessment of susceptibility of results to publication bias. Pain outcomes were participant-reported pain relief of ≥30% or ≥50%, or PGIC much or very much improved. RESULTS: Twenty-one reviews (87 trials, 17 631 patients) were included. All rated moderate (15) or high-quality (6) using AMSTAR-2 and at least seven of eight critical pain criteria were met by 13 of 21 reviews. Diagnosis of FMS used recognized criteria. Seven reviews found no trials (carbamazepine, clonazepam, lamotrigine, phenytoin, oxycodone, topiramate or valproate), seven had limited and inadequate data (antipsychotics, cannabinoids, combination therapy, gabapentin, lacosamide, monoamine oxidase inhibitors, NSAIDs) and two were subject to publication bias (amitriptyline, SSRI). Mirtazapine had moderate evidence of no effect. Duloxetine, milnacipran and pregabalin had moderate/good evidence of substantial pain relief for 4-12 weeks in around 1 in 10 adults with moderate or severe FMS pain, without evidence of efficacy beyond six months. Serious adverse events were no more common than with placebo. There was no evidence about who might benefit or experience adverse events. There was no substantial efficacy evidence for other medicines. CONCLUSIONS: Duloxetine, milnacipran and pregabalin had good evidence that about 1 person in 10 with moderate or severe pain experienced pain intensity reduction by at least 50%.