Weekly IM interferon beta‐1a in multiple sclerosis patients over 50 years of age

Background: Efficacy and safety data have not previously been compiled for intramuscular interferon beta‐1a (IM IFNβ‐1a) in patients with multiple sclerosis (MS) ≥ 50 years of age. We investigated the efficacy and safety of IM IFNβ‐1a in patients segregated by 50 and 40 years of age in separate meta‐analyses. Methods: The MS Clinical Research Group Study, the Controlled High‐Risk Subjects AVONEX^® (IM IFNβ‐1a) MS Prevention Study, the IFNβ‐1a European Dose‐Comparison Study, and a multicenter, open‐label antigenicity and safety study of human serum albumin‐free IM IFNβ‐1a were analyzed. Results: Overall, 906 patients (68 aged ≥ 50 years and 838 aged <50 years, or 323 aged ≥ 40 years and 583 aged <40 years) received IM IFNβ‐1a for ≥ 24 months. At baseline, patients ≥ 50 years had significantly higher Expanded Disability Status Scale scores than patients <50 years (3.4 vs. 2.8; P < 0.001), but fewer relapses in the three preceding years (2.6 vs. 3.4; P < 0.001); patients ≥ 40 years and <40 years exhibited similar differences. After 2 years of treatment, there were no significant differences in annualized relapse rate, sustained disability progression, time to sustained disability progression, or number of MRI‐identified gadolinium‐enhanced lesions between age groups in either analysis. The cumulative probability of relapse was significantly lower in patients ≥ 40 years versus patients <40 years (0.601 vs. 0.702; P < 0.001). Adverse event incidence did not differ significantly between age groups in either analysis. Conclusions: IM IFNβ‐1a is effective and well tolerated in patients with MS ≥ 40 and ≥ 50 years as well as younger patients.