Intravenous Immunoglobulin Therapy in Patients With Painful Idiopathic Small Fiber Neuropathy

Abstract

Objective This is the first double-blind randomized controlled trial evaluating the efficacy and safety of IV immunoglobulin (IVIG) vs placebo in patients with idiopathic small fiber neuropathy (I-SFN). Methods Between July 2016 and November 2018, 60 Dutch patients with skin biopsy–proven I-SFN randomly received a starting dose of IVIG (2 g/kg body weight) or matching placebo (0.9% saline). Subsequently, 3 additional infusions of IVIG (1 g/kg) or placebo were administered at 3-week intervals. The primary outcome was a 1-point change in Pain Intensity Numerical Rating Scale score at 12 weeks compared to baseline. Results Thirty patients received IVIG, and 30 received placebo. In both groups, 29 patients completed the trial. In 40% of patients receiving IVIG, the mean average pain was decreased by at least 1 point compared to 30% of the patients receiving placebo (p = 0.588, odds ratio 1.56, 95% confidence interval 0.53–4.53). No significant differences were found on any of the other prespecified outcomes, including general well-being, autonomic symptoms, and overall functioning and disability. Conclusions This randomized controlled trial showed that IVIG treatment had no significant effect on pain in patients with painful I-SFN. Trial Registration Information ClinicalTrials.gov Identifier: NCT02637700, EudraCT 2015-002624-31. Classification of Evidence This study provides Class I evidence that for patients with painful I-SFN, IVIG did not significantly reduce pain compared to placebo.