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Symptom Response to Low-Dose Naltrexone in Fibromyalgia: An Exploratory Analysis of the Randomized Placebo-Controlled
Maria Juul Nielsen1, Henrik Bjarke Vaegter2, Karin Due Bruun3
1Pain Research Group, Pain Center, Odense University Hospital, Odense, Denmark; Faculty of Health Sciences, University of Southern Denmark, Odense, Denmark.
Background:
Fibromyalgia (FM) remains difficult to manage due to a highly variable symptom profile. The "FINAL" randomized, placebo-controlled trial examined the efficacy of low-dose naltrexone (LDN) on pain in women with FM, showing no significant difference in pain reduction at the group level but potentially higher 30% pain response rates. Analysis of secondary outcomes showed potential improvements in memory problems.
Objectives:
This exploratory analysis aimed to further investigate individual responses to LDN treatment by analyzing 30% responder rates for six secondary FM outcomes.
Methods:
The FINAL trial included 99 women with FM who were randomized 1:1 to treatment with LDN or placebo for 12 weeks. Based on original data from this trial, 30% response rates were assessed for the six selected secondary outcomes: tenderness, fatigue, sleep disturbances, depression, memory problems, and stiffness. Risk ratios (RR) with 95% confidence intervals (CI) were calculated to assess differences between groups.
Results:
No significant differences were found between treatment groups for any of the symptom response categories. The highest RR was observed for memory (RR = 1.67, 95% CI: 0.82-2.95), followed by sleep (RR = 1.28, 95% CI: 0.92-2.64), stiffness (RR = 1.26, 95% CI: 0.84-2.89, p = .47), tenderness (RR = 1.16, 95% CI: 0.88-2.67), fatigue (RR = 1.10, 95% CI: (0.78-3.13) and depression (RR = 0.96, 95% CI: 0.92-2.66).
Conclusions:
Response rates for 30% improvement in six selected nonpain outcomes were similar after 12 weeks treatment with LDN or placebo in women with FM. Larger studies investigating 30% response rates are warranted.