Interferon beta in relapsing-remitting multiple sclerosis -: An eight years experience in a specialist multiple sclerosis centre

Background and objective Long-term observational studies may provide additional information about the behaviour of different drugs in the post-marketing period. We present the data of our cohort of relapsing-remitting multiple sclerosis (RRMS) patients treated with interferon beta (IFN beta). Methods We analysed RRMS patients followed for at least 2 years. From 1995, we initiated therapy with IFN beta. As they became available, patients were allocated to one of the IFNs at standard doses (IFN beta-1b, IFN beta-1a i.m. or IFN beta-1a s. c.). Each patient was included in a follow-up protocol containing demographic and baseline clinical data. Results Between 1995 and 2004, 382 patients have completed at least 2 years of follow-up. Significant differences at entry were observed. Patients on IFN beta-1b had a higher disease activity and disability at baseline than those on IFN beta-1a i.m. or IFN beta-1a.s.c. A significant reduction in the relapse rate was observed for the three drugs (70% for IFN beta-1b, 64% for IFN beta-1a i. m. and 74% for IFN beta-1a s. c.). We observed a sustained progression of disability in 11% of patients on IFN beta-1b, 17% on IFN beta-1a i. m. and 19% on IFN beta-1a s. c.; and at four years of follow-up in 24% of patients on IFN beta-1b, 23% on IFN beta-1a i. m. and 35% on IFN beta-1a s. c. No unexpected major adverse events were observed with any of the drugs. Conclusions Interferon beta is safe and well tolerated. The various registered interferon beta drugs provide a comparable efficacy in a large non-selected cohort of RRMS patients.