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Introduction
Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is a rare and often disabling chronic progressive or relapsing neuropathy. 1 2 Several data point to an immune pathogenesis of CIDP, 3 including the improvement observed in most patients after therapy with corticosteroids, plasma exchange and high-dose intravenous immunoglobulin (IVIg). 4-7 Two randomised controlled trials (RCTs) showed a comparable short-term efficacy of IVIg and oral corticosteroids 8 and of IVIg and plasma exchange, 9 while a recent RCT (the Immunoglobulin Methylprednisolone for CIDP (IMC) study) showed that 6-month therapy with IVIg was more frequently effective and tolerated than treatment with intravenous methylprednisolone (IVMP). 10 Little is known on the long-term effect of these therapies and on the duration of their effect after discontinuation. In two RCTs, discontinuation of IVIg after 6-month therapy was followed by clinical deterioration within 6 months in approximately half of the patients. 11 12 In one 11 of these studies, therapy continuation was more effective than placebo up to 48 weeks. The follow-up extension 13 of the PREDICT study 14 showed that the median time to relapse after discontinuation of 6-month therapy ranged from 11 months for oral prednisolone to 17.5 months for pulsed high-dose dexamethasone. In the IMC study, 10 a significantly higher proportion of patients relapsed and required further therapy within 6 months after IVIg (38.1%) than did patients after IVMP discontinuation (0/10). We have now extended the follow-up of this study to compare the proportion of patients who eventually deteriorated and resumed therapy during the follow-up and the time to clinical deterioration after discontinuing 6-month therapy with IVIg or IVMP.
Patients
We retrospectively reviewed the follow-up of patients included in the IMC study after the last scheduled visit of the trial, 6 months after therapy discontinuation. Of the 45 patients included in the IMC study, 42 patients were available at follow-up, as three patients (all on IVMP) had retired from the original study for adverse events (1) or voluntary withdrawal (2) and refused further therapy within the trial. 10 In the original study, patients who had failed to respond to one therapy were blindly treated for 6 months with the alternative therapy. We included these patients in the analysis of the long-term efficacy of the therapies. They included 8 patients treated...