Interferon-beta dose and efficacy: the OPTIMS study.

Interferon beta (IFN-beta) reduces exacerbation rates in patients with relapsing-remitting multiple sclerosis (MS), but some patients do not respond to treatment. Recent studies have shown a clear dose-response effect on the reduction of exacerbation rates, and on burden of disease accumulation and active lesion frequency seen on MRI. During treatment with 8 MIU IFN-beta we noticed a 30% rate of treatment failure. We then treated non-responders with 12 MIU IFN-beta and observed significant improvement in the clinical signs of disease activity. In order to compare the efficacy of two different doses of IFN-beta-1b, a multicenter study for the optimization of interferon for MS (OPTIMS) has been organized. The design of the study is presented here.