• efficacy;
  • interferon beta;
  • meta-analysis;
  • multiple sclerosis;
  • patient age;
  • safety

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; < 0.001), but fewer relapses in the three preceding years (2.6 vs. 3.4; < 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; < 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.