Final analysis of the European multicenter trial on IFNbeta-1b in secondary-progressive MS.

BACKGROUND

Based on a prospectively planned interim analysis, the European study of interferon beta-1b (IFNbeta-1b) provided evidence that the treatment delays neurologic deterioration in patients with secondary progressive MS (SPMS). The authors analyzed all data collected until closure of the double-blind study to further scrutinize the consistency of the findings.

METHODS

The multicenter, double-blind, randomized, placebo-controlled trial treated patients for up to 36 months. The primary and all secondary endpoints of this study were evaluated using the data set at study termination, with a mean follow-up under double-blind conditions of 1054 +/- 199 and 1068 +/- 176 days for the placebo and IFNbeta-1b group. Alternative and more demanding definitions of disease progression were explored. Confirmed progression was analyzed in subgroups according to baseline demographics and baseline indicators of disease activity.

RESULTS

Forty-eight of 358 placebo and 40 of 360 IFNbeta-1b-allocated patients were lost to follow-up. Time to confirmed 1.0-point Expanded Disability Status Scale (EDSS) progression for patients receiving IFNbeta-1b was delayed (p = 0.007). The proportion of patients with a confirmed 2.0-point EDSS progression was approximately 27% lower for the group treated with IFNbeta-1b, both including and excluding EDSS data collected during relapses. The proportion of patients with either progression or relapses decreased by nearly 30% in patients treated with IFNbeta-1b compared with placebo. Analysis of subgroups suggests that patients with higher prestudy disease activity (more than two relapses or EDSS progression by more than 1.0 point or both) seem to have a more pronounced treatment effect.

CONCLUSION

Analysis of the data set at study termination including additional post hoc outcome measures is consistent with the original findings, thus supporting the conclusion that treatment with IFNbeta-1b is effective in patients with SPMS fulfilling the inclusion criteria of this study.