Randomized trial of intravenous immunoglobulin maintenance treatment regimens in chronic inflammatory demyelinating polyradiculoneuropathy

Background and purpose: High peak serum immunoglobulin G (IgG) levels may not be needed for maintenance intravenous immunoglobulin (IVIg) treatment in chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) and such high levels may cause side effects. More frequent lower dosing may lead to more stable IgG levels and higher trough levels, which might improve efficacy. The aim of this trial is to investigate whether high frequent low dosage IVIg treatment is more effective than low frequent high dosage IVIg treatment.

Methods: In this randomized placebo-controlled crossover trial, we included patients with CIDP proven to be IVIg-dependent and receiving an individually established stable dose and interval of IVIg maintenance treatment. In the control arm, patients received their individual IVIg dose and interval followed by a placebo infusion at half the interval. In the intervention arm, patients received half their individual dose at half the interval. After a wash-out phase patients crossed over. The primary outcome measure was handgrip strength (assessed using a Martin Vigorimeter). Secondary outcome indicators were health-related quality of life (36-item Short-Form Health Survey), disability (Inflammatory Rasch-built Overall Disability Scale), fatigue (Rasch-built Fatigue Severity Scale) and side effects.

Results: Twenty-five patients were included and were treated at baseline with individually adjusted dosages of IVIg ranging from 20 to 80 g and intervals ranging from 14 to 35 days. Three participants did not complete the trial; the main analysis was therefore based on the 22 patients completing both treatment periods. There was no significant difference in handgrip strength change from baseline between the two treatment regimens (coefficient -2.71, 95% CI -5.4, 0.01). Furthermore, there were no significant differences in any of the secondary outcomes or side effects.

Conclusions: More frequent lower dosing does not further improve the efficacy of IVIg in stable IVIg-dependent CIDP and does not result in fewer side effects.