Racial and ethnic disparities in disease-modifying therapy use among adults with multiple sclerosis: a real-world analysis of the All of Us Research Program

Abstract

Introduction Racial and ethnic disparities in multiple sclerosis (MS) disease-modifying therapy (DMT) use are documented but incompletely characterized across the full treatment pathway. Methods We conducted a retrospective cohort study using the All of Us Research Program (2024 data release) among adults aged ≥18 years with confirmed MS (N = 3,508). Outcomes included DMT initiation, time to first DMT, drug class selection, switching, escalation, and discontinuation. High-efficacy DMTs were defined as agents with ≥50% relative reduction in annualized relapse rate. Analyses were descriptive; race and ethnicity were self-reported. Results Overall, 1,564 patients (44.6%) initiated DMT. Hispanic patients had the lowest initiation rate (36.2% vs. 45.6% non-Hispanic). Black patients had the highest within-group initiation rate (49.2%) but the longest median time to first DMT (1,497 days vs. 1,217 days in White patients). High-efficacy DMT exposure ranged from 11.9 to 24.0% across race–sex strata, and 76.3% of assessable initiators met the 180-day discontinuation threshold (range 71.7–80.5%). Discussion Most patients with MS in this national cohort never initiated DMT. Hispanic patients showed the lowest initiation rates, while Black patients experienced the longest delays to treatment. The two groups’ patterns are consistent with mechanistically distinct barriers, possible limited system entry for Hispanic patients and possible delayed specialty access for Black patients. High-efficacy DMT utilization remained low across all groups. Equitable and timely access to DMT, including high-efficacy agents, is urgently needed to reduce long-term disability across all populations.