Clinical characteristics and disease burden of African, Caribbean, and Black people with multiple sclerosis in Toronto, Canada

Background: Different racial and ethnic groups have demonstrated heterogeneity in the clinical course of multiple sclerosis(MS).

Objective: We aimed to evaluate disease characteristics in African, Caribbean, and Black people with MS(ACB-MS) followed at a single centre in Toronto, Canada.

Methods: ACB-MS were compared with age- and sex-matched people with MS (pwMS) of European descent(EUR-MS) identified through the clinic registry.

Results: 344 PwMS were included(n = 172 ACB-MS, n = 172 EUR-MS; mean age 43 years, 68 % female). Baseline mean Expanded disability status scale (EDSS) scores (ACB-MS 2.3 ± 2.3 vs. EUR-MS 2.2 ± 2.0, p = 0.38) and subsequent clinical and radiological measures of disease activity were similar between groups, including annualized relapse rate (ARR)(ACB-MS 0.47 ± 0.47 vs. EUR-MS 0.41 ± 0.34, p = 0.2) and most recent EDSS (ACB-MS 2.7 ± 2.2 vs. EUR-MS 2.3 ± 2.1, p = 0.10). However, the proportion of MRI brain demonstrating new disease activity was higher(37% vs. 26 %, p < 0.05) and disability progression greater in ACB-MS vs. EUR-MS(43% vs. 33 %,p < 0.05) but measures of disease severity including MS Severity Score(3.17 vs. 2.58, p = 0.3) and Progression Index(PI) (0.27 vs. 0.30, p = 0.5) were comparable.

Conclusion: Disability progression was seen more commonly in ACB-MS, though clinical disease activity and severity were generally comparable between ACB-MS and EUR-MS patients in Toronto, Canada. These findings partially differ from prior studies demonstrating more overtly aggressive MS disease courses in Black and African American PwMS, necessitating further studies to understand how structural determinants of health drive these disparities.