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 (IFNbeta).
Methods: We analysed RRMS patients followed for at least 2 years. From 1995, we initiated therapy with IFNbeta. As they became available, patients were allocated to one of the IFNs at standard doses (IFNbeta-1b, IFNbeta-1a i.m. or IFNbeta-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 IFNbeta-1b had a higher disease activity and disability at baseline than those on IFNbeta-1a i.m. or IFNbeta-1a s.c. A significant reduction in the relapse rate was observed for the three drugs (70% for IFNbeta-1b, 64% for IFNbeta-1a i.m. and 74% for IFNbeta-1a s.c.). We observed a sustained progression of disability in 11% of patients on IFNbeta-1b, 17% on IFNbeta-1a i.m. and 19% on IFNbeta-1a s.c.; and at four years of follow-up in 24% of patients on IFNbeta-1b, 23% on IFNbeta-1a i.m. and 35% on IFNbeta-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.