Clinical Course of Relapsing-Remitting Multiple Sclerosis (RRMS) in Non-White MS Patients

Background: A growing body of literature suggests there may be differences in multiple sclerosis (MS) baseline characteristics/severity across ethnic groups. Most data are derived from registries or individual practices, but detailed clinical trial data are limited.

Objectives: Describe baseline characteristics and MS clinical course in White and non-White subjects from 6 randomized, placebo-controlled trials.

Methods: Subjects randomized to placebo from the MSCRG, AFFIRM, DEFINE, CONFIRM, SELECT and ADVANCE studies were grouped into 4 racial/ethnic groups: White, Black, Asian and Hispanic. Baseline characteristics and clinical/radiological outcomes were evaluated (White subjects as reference group). Hispanic status was only collected in AFFIRM, hence these subjects (n=22) were not included in the analyses.

Results: In total, 1,655 White, 29 Black and 141 Asian subjects were included in the analysis. Baseline demographic and disease characteristics were similar between Black and White subjects. Versus White subjects, Asian subjects had a significantly lower mean age (34.3 vs 37.2 y White), higher mean EDSS score (2.8 vs 2.5), higher mean number of relapses in prior year (1.6 vs 1.4), shorter duration of MS (5.7 vs 7.5 y), and a lower proportion of those previously treated with disease-modifying therapy (DMT; 22.0 vs 33.2%). Over the studies’ duration, Black subjects had a higher risk of EDSS progression (Hazard ratio [95% CI]: 3.6 [2.02, 6.45]; P<0.0001) and significantly greater mean changes from baseline versus White subjects in EDSS score at Year 1 (0.6 vs 0.1 White) and Year 2 (1.1 vs 0.3). No significant differences were observed in relapse endpoints between White and non-White subjects, except for a trend for a higher adjusted annualized relapse rate in Black versus White subjects (rate ratio; 1.65 [95% CI: 0.95, 2.87]; P=0.0749).

Conclusions: In this analysis of placebo-treated subjects from 6 MS clinical trials, several differences were noted between non-White and White subjects. Over the course of the studies, baseline disease seemed to be more severe in the Asian population and disability outcomes were worse in Black versus White subjects. Interpretation of results is methodologically limited by pooling across trials and low numbers of non-White subjects. These results highlight the need to increase recruitment of non-White subjects into MS clinical trials to gain better understanding of disease activity and response to DMT in these populations.