Enhanced benefit of increasing interferon beta-1a dose and frequency in relapsing multiple sclerosis: The EVIDENCE study

Abstract

Background: The EVIDENCE (Evidence of Interferon Dose-Response: European North American Comparative Efficacy) Study demonstrated that patients with multiple sclerosis (MS) who initiate interferon beta-1a therapy with 44 μg 3 times weekly (TIW) were less likely to have a relapse or activity on magnetic resonance imaging (MRI) compared with those who initiate therapy at a dosage of 30 μg 1 time weekly (QW). Objective: To determine the effect of changing the dosage from 30 μg QW to 44 μg TIW in this extension of the EVIDENCE Study. Design/Patients: Patients with relapsing MS originally randomized to interferon beta-1a, 30 μg QW, during the comparative phase of the study changed to 44 μg TIW, whereas patients originally randomized to 44 μg TIW continued that regimen. Patients were followed up, on average, for an additional 32 weeks. Main Outcome Measure: The within-patient pretransition to posttransition change in relapse rate. Results: At the transition visit, 223 (73%) of 306 patients receiving 30 μg QW converted to 44 μg TIW, and 272 (91%) of 299 receiving 44-μg TIW continued the same therapy. The posttransition annualized relapse rate decreased from 0.64 to 0.32 for patients increasing the dose (P