Background: Fibromyalgia is a chronic disorder characterized by pain and psychological symptoms in adults. Several randomized controlled trials (RCTs) have shown the effectiveness and safety of low-dose naltrexone (LDN) in the treatment of fibromyalgia in variable small settings. Hence the need to conducted a meta-analysis to evaluate the overall effect and the strength of evidence.
Methodology: PUBMED, CENTRAL, and ClinicalTrials.gov were searched to retrieve RCTs comparing naltrexone with placebo in fibromyalgia patients for systematic review and meta-analysis. We conducted pairwise meta-analyses using DerSimonian and Laird random-effects model via RevMan 5.4. We reported dichotomous outcomes as relative risk (RR) and continuous outcomes as standardized mean difference (SMD) with 95% confidence intervals (CIs). Quality of included RCTs was assessed using revised Cochrane Risk of Bias Tool for RCTs (RoB 2.0). Heterogeneity was detected by Chi2 and I 2 values for each meta-analysis and if significant, sensitivity analysis was performed.
Results: We included five RCTs in meta-analysis. Our results estimated that LDN is superior to placebo in alleviating pain both in primary (SMD -0.61; 95% CI -1.14, -0.08) and sensitivity analysis (SMD -0.87; 95% CI -1.28, -0.46) but not in raising mechanical pain threshold (SMD 0.24; 95% CI -0.09, 0.56) in fibromyalgia patients. Neither the primary (RR 1.68; 95% CI 0.84, 3.36) nor sensitivity analysis (RR 0.98; 95% CI 0.72, 1.34) could associate LDN use with the incidence of headache. The incidence of vivid dreams (RR 2.41; 95% CI 1.77, 3.28) was significantly higher in treatment group as compared to placebo.
Conclusion: LDN is considered to be effective in the treatment of fibromyalgia. No serious adverse effects were reported in treatment group. There is need for more RCTs to support the evidence.
Keywords: LDN; fibromyalgia; low-dose naltrexone; naltrexone.
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