Magyari, M2; Koch-Henriksen, N2; Laursen, B2; Sørensen, P S3
1 Department of Clinical Medicine, Department of Clinical Medicine, Faculty of Health and Medical Sciences, Københavns Universitet2 unknown3 Department of Clinical Medicine, Department of Clinical Medicine, Faculty of Health and Medical Sciences, Københavns Universitet
BACKGROUND: Gender appears to play a role in incidence and disease course of multiple sclerosis (MS). OBJECTIVE: The objective was to determine whether male and female patients with MS respond differently to interferon-beta treatment in terms of reduction in relapse rates. METHODS: We included all 2033 patients with relapsing-remitting MS who started treatment with interferon-beta from 1996 to 2003, identified from the Danish Multiple Sclerosis Treatment Register. We defined neutralizing antibody (NAb)-positive and NAb-negative periods in the single patient by the results of the NAb tests. Patients served as their own controls, and relapse rates were compared between NAb-negative and NAb-positive periods. RESULTS: NAbs significantly abrogated the interferon-beta treatment efficacy in both genders. The all-over women:men relapse rate ratio irrespective of NAb status was 1.47 (95%CI; 1.28-1.68). In a generalized linear Poisson models analysis with relapse counts as response variable, the main effects NAbs, sex, age at treatment start and number of relapses in 2 years before treatment start were strongly significant, but the effect of NAbs on relapse rates did not differ significantly between men and women. CONCLUSION: As NAbs influenced the on-treatment relapse rates strongly in both sexes but without statistical significant difference, there is no indication of different effects of interferon-beta in men or women.