Dose of intravenous immunoglobulins in chronic inflammatory demyelinating polyneuropathy

The usual initiating dose of intravenous immunoglobulins (IVIg) in the treatment of chronic inflammatory demyelinating polyneuropathy (CIDP) is 2 g/kg/course. Although not evidence based, subsequent reductions are advised to the lowest possible level for maintenance. In practice, the achievable levels of such reductions and their impact on treatment frequency have not been studied. Factors determining maximal dosage reduction are unknown. We retrospectively reviewed data concerning IVIg therapy for 15 patients with CIDP, from their medical records between 1997 and 2005. Lowest effective dose and treatment frequency were determined. The following correlations were ascertained: dose to frequency, dose to weight, dose to disease duration, amplitude of dose reduction to disease duration, and dose to pre-therapeutic disease severity. Dose reductions were possible in all (mean: 63.3%, range: 42.4-88%). The lowest effective dose of IVIg per course and treatment frequency were both very variable (18-108 g and 2-17 weeks, respectively). Lowest dose per course did not correlate to weight, frequency of administration, disease duration, or pre-therapeutic degree of disability. Amplitude of dose reduction achieved was independent of disease duration. Treatment frequency could not be lowered in any patient. Our findings show that IVIg target doses should be titrated individually but suggest that infusion frequencies are fixed in each case in relapsing CIDP. Importantly, lower dose treatment is not associated with shorter intervals between courses, and lowest effective dose is independent of weight and disease duration. Initial level of disability does not appear to influence dose required. These results suggest considerably lower, standardized, initiating, and maintenance doses might be effective and highlight the need for prospective dose comparative trials.