Aggressive relapsing multiple sclerosis characterized by rapid disability progression

Criteria for identifying relapsing multiple sclerosis (RMS) patients with aggressive disease, which would be useful for clinical decision making, are currently unavailable.

Identify RMS patients with aggressive disease characterized by rapid disability progression.

Data from a 2-year, phase 3, double-blind, placebo-controlled trial with long-term follow-up evaluations of RMS patients taking either intramuscular interferon beta-1a (IM IFNβ-1a, 30μg) or placebo with baseline Expanded Disability Status Scale (EDSS) scores of 1.0-3.5 were retrospectively analyzed. Patients with a ≥2.0-point increase in EDSS score, resulting in a score ≥4.0 by study end, were considered to have aggressive RMS. The risk of a poor long-term outcome, defined as an EDSS score ≥8.0 at 8 years of follow-up, was calculated as an odds ratio from a logistic regression model comparing patients with and without aggressive RMS.

Only 25 patients met the criteria for aggressive RMS. Among these patients, mean disease duration was 5.1±3.85 years, mean baseline age was 37.2±6.35 years, and mean baseline EDSS score was 2.8±0.74. Fewer IM IFNβ-1a-treated than placebo-treated patients met the criteria for aggressive RMS at 2 years (7% vs 22% on placebo, p=0.0072). Thirteen patients reached the EDSS milestone of ≥8.0 by the end of the 8-year follow-up. The odds ratio for attaining severe disability was 86.4 (95% CI, 10.3-726.4; p<0.0001) for patients with aggressive RMS compared to patients without aggressive RMS.

Defining aggressive RMS based on rapid EDSS progression was useful in identifying patients at risk for more severe disease course.