Randomised trial of intravenous immunoglobulin maintenance treatment regimens in chronic inflammatory demyelinating polradiculoneuropathy.

BACKGROUND High peak serum IgG levels may not be needed for maintenance treatment of Intravenous immunoglobulin (IVIg) in chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) and cause side-effects. More frequent lower dosing may lead to more stable IgG levels and higher trough levels which might improve its efficacy. METHODS In this randomized placebo-controlled cross-over trial we included CIDP patients 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 hand grip strength (Vigorimeter). Secondary outcome indicators were health related quality of life (SF-36), disability (I-RODS), fatigue (R-FSS) and side-effects. RESULTS Twenty-five patients were included and were treated at baseline with individual adjusted dosages of IVIg ranging from 20-80 grams and intervals ranging from 14-35 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 Vigorimeter 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.