Interferon beta treatment in relapsing-remitting multiple sclerosis: a post-marketing study in Lombardia, Italy. Multiple Sclerosis Centers of Lombardia, Italy.

The aim of the study was to evaluate the efficacy of interferon beta-1a (IFN-beta-1a) and beta-1b (IFN-beta-1b) in clinical practice for the treatment of relapsing-remitting multiple sclerosis (RR MS). Patients were selected and prospectively monitored according to a predefined protocol. An appropriate form was prepared to collect clinical data of multiple sclerosis patients attending the MS Centers of Lombardia, Italy. On 30 June 1998, 317 patients were treated with IFN-beta-1b and 156 with IFN-beta-1a. Basal expanded disability status scale (EDSS) and relapse frequency were similar in both groups of patients. The annual relapse rate consistently decreased from 1.76 to 0.63 at 1 year and to 0.51 at 2 years for the IFN-beta-1b group and from 1.6 to 1.0 at 1 year for the IFN-beta-1a group. Disability remained stable in most patients. Dropouts (20.5%) were affected by more active disease compared to patients who continued to be treated. This study confirms the efficacy of both treatments, showing a more marked effect than expected from the clinical trials' results, probably due to differences in selection criteria and exclusion of dropouts.