Abstract: Our searches identified six randomised, double-blind studies involving 292 participants in suitably characterised fibromyalgia. The mean age of participants was between 39 and 50 years, and 89% to 100% were women. The initial pain intensity was around 7/10 on a 0 to 10 pain scale, indicating severe pain. NSAIDs tested were etoricoxib 90 mg daily, ibuprofen 2400 mg daily, naproxen 1000 mg daily, and tenoxicam 20 mg daily; 146 participants received NSAID and 146 placebo. The duration of treatment in the double-blind phase varied between three and eight weeks. Not all studies reported all the outcomes of interest. Analyses consistently showed no significant difference between NSAID and placebo: substantial benefit (at least 50% pain intensity reduction) (risk difference (RD) -0.07 (95% confidence interval (CI) -0.18 to 0.04) 2 studies, 146 participants; moderate benefit (at least 30% pain intensity reduction) (RD -0.04 (95% CI -0.16 to 0.08) 3 studies, 192 participants; withdrawals due to adverse events (RD 0.04 (95% CI -0.02 to 0.09) 4 studies, 230 participants; participants experiencing any adverse event (RD 0.08 (95% CI -0.03 to 0.19) 4 studies, 230 participants; all-cause withdrawals (RD 0.03 (95% CI -0.07 to 0.14) 3 studies, 192 participants. There were no serious adverse events or deaths. Although most studies had some measures of health-related quality of life, fibromyalgia impact, or other outcomes, none reported the outcomes beyond saying that there was no or little difference between the treatment groups. We downgraded evidence on all outcomes to very low quality, meaning that this research does not provide a reliable indication of the likely effect. The likelihood that the effect could be substantially different is very high. This is based on the small numbers of studies, participants, and events, as well as other deficiencies of reporting study quality allowing possible risks of bias. There is only a modest amount of very low-quality evidence about the use of NSAIDs in fibromyalgia, and that comes from small, largely inadequate studies with potential risk of bias. That bias would normally be to increase the apparent benefits of NSAIDs, but no such benefits were seen. Consequently, NSAIDs cannot be regarded as useful for treating fibromyalgia.

Plain-language summary: We searched for clinical trials in which NSAIDs were used to treat symptoms of fibromyalgia in adults. The latest search was in January 2017. Six studies satisfied the inclusion criteria, randomising 292 participants to treatment with NSAID or placebo. NSAIDs tested were etoricoxib 90 mg daily, ibuprofen 2400 mg daily, naproxen 1000 mg daily, and tenoxicam 20 mg daily; 146 participants received NSAID and 146 placebo. Study duration was between three and eight weeks. Not all studies reported the outcomes of interest. We found no difference between NSAID or placebo for a range of outcomes. Pain reduction by half or better was experienced by 1 in 10 with NSAID and 2 in 10 with placebo. Pain reduction by a third or better was experienced by about 2 in 10 with both NSAID and placebo. Side effects were experienced by 3 in 10 with NSAID and 2 in 10 with placebo. The evidence was of very low quality. This means that the research does not provide a reliable indication of the likely effect. The chance that the real effect of NSAIDs could be substantially different is very high. Small studies like those in this review tend to overestimate results of treatment compared to the effects found in larger, better studies. The very low-quality evidence and the lack of any obvious benefit mean that NSAIDs cannot be regarded as useful for the management of fibromyalgia.