OBJECTIVES: To compare rates of emergency room (ER) visits among multiple sclerosis (MS) patients treated with disease-modifying therapies (DMT) by race/ethnicity.

METHODS: Newly diagnosed adult MS patients (ICD-10-CM: G35) initiating DMT (index) between January 1, 2018, and June 30, 2023, were identified in CHRONOS, a linked open claims, closed claims, and social determinants of health database. Patients had at least one month of continuous enrollment before the first diagnosis and a DMT submitted on a claim in the closed or open claims data. Incidence rate ratios (IRRs) and 95% confidence intervals (CIs) are reported from Poisson regression models, adjusted for baseline demographics, comorbidities, and HCRU, and were weighted to account for censoring over the one-year follow-up. The model compared rates of ER visits between White (reference), Black, Hispanic, and Asian patients over 360 days of follow-up. All study variables were defined by NDC, CPT, HCPCS, and ICD-10-CM codes.

RESULTS: Newly diagnosed MS patients (n=3,599) were on average 41.1 (SD:11.1) years old at index and 72.5% female. The race/ethnic breakdown was 78.7% White, 10.9% Black, 9.1% Hispanic, and 1.3% Asian. Over the 360-days after index, Black [IRR:1.4(1.2-1.5)] and Hispanic [IRR:1.1(1.0-1.3)] patients were more likely and Asian [IRR:0.7(0.5-0.90] patients less likely than White patients to visit an ER.

CONCLUSIONS: The current analysis of MS patients treated with a DMT in a real-world database found rates of ER visits over the first year after treatment initiation were highest in Black and Hispanic patients. Further analysis exploring potential causes for more frequent ER visits in these populations, such as uncontrolled comorbid conditions, is warranted to identify areas of intervention for clinicians and reduce disparities.