Our data show that IV-Prednisolone appears to be as effective as IVIg and oral prednisone in the initial and long-term management of patients with CIDP. In patients treated with IVMP, strength, as measured by quantitative muscle testing, improved on average by 18% withinthe first 6 months and by 27% at the time of last follow-up, on average after 4.6 years. There were no statistically significantdifferences in mean improvement in strength within 6 months, or at the last follow-up, when compared with patients treatedwith IVIg (26% at 6 months, 31% at 3.6 years) or oral immunosuppression (12% at 6 months, 40% at 4.7 years). We also found no statistically significant difference in the frequency of improvement when comparing our 3 groups at the time of last follow-up, with more than 80% of patients improved in each group. However, within the first 6 months, more patients treated with IVMP (77%) and IVIg (100%) improved than with oral immunosuppression (38%) (P = .04). Previous studies also suggest that relatively prolonged treatment of CIDP with oral corticosteroids might be needed before patients improve.4 Although the presence of less severe baseline weakness in patients treated with IVMPcompared with oral immunosuppression might partly explain the benefit in this group, we think it unlikely. Even though patients receiving IVMP started out with greater baseline strength, all 3 groups improved to a similar degree, suggesting similar beneficialeffects from all 3 medications. Furthermore, there was no significant difference in baseline strength between patients receiving IVMPcompared with IVIg, and improvement was similar in these 2 groups, suggesting that each of these 2 medications had comparable beneficial effects.
Two prior reports discuss the shorter-term use of IV corticosteroids to treat CIDP. Molenaar et al25 described 10 patients treated with 6 cycles of 40 mg of dexamethasone for 4 consecutive days over 19 weeks. Three patients discontinued treatment, 1 because of adverse effects and 2 because of deterioration. The patients who completed the treatment course all had objective improvement. In another study, reported only as an abstract, 5 patients were treated with IVMP 1000 mg/d for 5 days and then with 1000 mg every 1 to 8 weeks, depending on the clinical response. All patients had improved motor and sensory function. No adverse effects were noted except for flushing and euphoria with theinfusion.
Drawbacks of our study include its open-label, retrospective nature and nonstandardized treatment regimes and evaluations. To simplify comparisons, we included patients treated with oral prednisone and oral cyclosporine in the same group. A randomizedprospective trial could definitively address whether IVMP is as efficacious as IVIg or oral prednisone. However, even with these drawbacks, our data are consistent with the earlier findings that IVMP treatment is followed by improvement in strength and can be used as initial therapy in patients with CIDP, even those with severe weakness.
Our data are the first to suggest that IVMP can be used long-term for many years to maintain improved strength. One of the main drawbacks of long-term oral corticosteroid treatment is the high likelihood of adverse effects.5 In our study, 58% of patients treated with oral corticosteroids had weight gain orcushingoid appearance. In contrast, only 19% of patients treated with IVMP had similar adverse effects. Another outcome indicated that the addition of a steroid-sparing agent was uncommon (31%) and less frequent than in patients receiving oral prednisone (100%)—suggesting a low incidence of prominent adverse effects in patients receiving IVMP. Although not statistically significant, the development of hyperglycemia or diabetes was more than 2.5 times as common in patients treated with oral prednisone compared with IVMP. Other adverse effects were rare and not significantly more common with IVMP than with oral prednisone.
The most common adverse effect in patients treated with IVMP was a 24- to 48-hour syndrome characterized by insomnia, restlessness,heartburn, flushing, sweating, and facial erythema, occurring in 38% of patients. This syndrome was transient and not severeenough to warrant discontinuation of the medication. This syndrome was as common as the transient syndrome of headache, nausea, and chills that occurred in patients treated with IVIg.
In summary, our study shows that IVMP is as effective in improving and maintaining strength as IVIg or oral immunomodulating treatments. It is much less expensive than IVIg, oral prednisone, or plasma exchange27 and is easily administered over a period of a few hours in an outpatient infusion center or at home. Intermittent high-dose IVMP also has fewer adverse effects than daily administrationof prednisone, whose adverse effects often limit its use. Intermittent IV methylprednisolone should be considered as an initial therapy and for long-term use in patients with weakness or disability due to CIDP.
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