Subgroups of multiple sclerosis patients with larger treatment benefits: a meta-analysis of randomized trials.

BACKGROUND AND PURPOSE: No subgroups of patients with higher treatment effects have been clearly detected in multiple sclerosis (MS). The aim of the present work was to evaluate whether there are subgroups of relapsing-remitting MS (RRMS) patients who are more responsive to treatments. METHODS: All published randomized clinical trials in RRMS reporting a subgroup analysis of treatment effect were collected. Two main outcomes, the annualized relapse rate (ARR) and the disability progression, were studied. The treatment effect in each subgroup was reported as a relative effect (RE), defined as the treatment effect in the subgroup relative to the overall effect. A meta-analysis was run to compare the RE between subgroups. RESULTS: Six trials (6693 RRMS patients) were included. Treatment effects on ARR were significantly higher in younger than in older subjects (RE = 0.83 vs. RE = 1.30, P < 0.001), in patients with than those without gadolinium activity (RE = 0.86 vs. RE = 1.15, P = 0.005) and in patients with lower than in those with higher Expanded Disability Status Scale (RE = 0.96 vs. RE = 1.23, P = 0.02), and on disability progression in younger than in older subjects (RE = 0.82 vs. RE = 1.28, P = 0.017). CONCLUSIONS: This study formally shows that in RRMS higher treatment effects are associated with characteristics of earlier (lower age and Expanded Disability Status Scale) and more active (higher gadolinium activity) disease.