There was no clinical pain relief from intravenous immunoglobulin (IVIg) therapy observed for patients with painful idiopathic small fiber neuropathy (I-SFN), according to study findings published in Neurology.
Study researchers conducted a randomized, placebo-controlled, double-blind clinical trial (ClinicalTrials.gov Identifier: NCT02637700) to assess the efficacy and safety of IVIg in patients with I-SFN. They recruited patients (N=60) with I-SFN at the Maastricht University Medical Center in The Netherlands between 2016 and 2019. Stratified by age and sex, patients were randomly assigned to receive 100 mg/mL GamunexÓ 10% with a 2 g/kg uploading dose (n=30) or placebo (n=30) for 12 weeks. Patients were assessed at 3- and 6-month follow-ups for changes in pain symptoms as measured by the 11-point Pain Intensity Numeric Rating Scale.
Patients in the treatment and placebo groups had a mean age of 48.7 (standard deviation [SD], 11.1) and 50.7 (SD, 9.7) years, 33.3% and 40.0% were men, 93.3% and 96.7% were White, and SFN was diagnosed a median of 7.8 (range, 1.3-58.5) and 7.4 (range, 1.7-34.9) years previously, respectively.
Among all participants, baseline average pain was 5.8 (range, 1.7-9.5), maximum pain was 7.0 (range, 2.2-10.0), and median daily sleep interference scale (DSIS) was 5.5 (range, 0.0-9.0).
In the per-protocol analysis, IVIg therapy was not significantly associated with an at least 1-point (odds ratio [OR], 1.89; 95% CI, 0.61-6.04; P =.415) or at least 2-point (OR, 1.73; 95% CI, 0.47-6.79; P =.624) decrease in average pain.
At 3 months, IVIg treatment was associated with a change to DSIS score (-1.57 vs -0.18; P =.045), neuropathic pain scale (NPS) intense score (-2.33 vs -0.77; P =.011), NPS hot score (-1.75 vs 0.15; P =.021), NPS unpleasant score (-2.08 vs -0.62; P =.022), short-form 36 (SF-36) physical functioning score (12.3 vs 2.11; P =.027), SF-36 vitality score (8.59 vs -0.24; P =.036), and SF-36 health change score (34.38 vs 12.50; P =.016) compared with placebo. At 6 months, only DSIS scores remained significantly different between groups (-1.64 vs 0.51; P =.006).
Serious adverse events included a single case each of headache, hospitalization, pulmonary embolism, and suicide attempt among the treatment group and an aorta coarctation repair among the placebo cohort. All of the serious events in the treatment group except hospitalization (for multiple complaints) occurred during the follow-up phase.
For common adverse events, IVIg recipients reported more headache (100% vs 56.7%; P <.001), nausea (63.3% vs 23.3%; P =.004), vomiting (36.7% vs 0.0%; P =.001), and rash (26.7% vs 0.0%; P =.005) than placebo recipients.
This study was limited by its power due to its low sample size, in which the investigators were only able to detect a response rate of 25% or greater.
These data indicated IVIg therapy was not effective for decreasing pain among patients with I-SFN.
Disclosure: Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please refer to the original reference for a full list of disclosures.
Geerts M, de Greef BTA, Sopacua M, et al. Intravenous immunoglobulin therapy in patients with painful idiopathic small fiber neuropathy. Neurology. Published online March 25, 2021. doi:10.1212/WNL.0000000000011919