Rapid disease course in African Americans with multiple sclerosis

Objective: To investigate utility of a Multiple Sclerosis Severity Scale (MSSS)–based classification system for comparing African American (AA) and white American (WA) multiple sclerosis (MS) subpopulations in the New York State Multiple Sclerosis Consortium (NYSMSC) database. MSSS is a frequency-rank algorithm relating MS disability to disease duration in a large, untreated reference population. Design/Methods: Distributions of patients in 6 MSSS-based severity grades were calculated for AA and WA registrants. Results: There were 419 AA and 5,809 WA patients in the NYSMSC, who had EDSS recorded during years 1–30 since symptom onset. Median EDSS was not different in AA and WA (3.5 vs 3.0, p = 0.60), whereas median MSSS in AA was higher than in WA (6.0 vs 4.8, p = 0.001). AA patients were overrepresented in the 2 most severe grades (41.5% vs 29.3% for WA) and underrepresented in the 2 lowest grades (23.4% vs 35.4%; p Conclusions: The 6-tiered MSSS grading system is a powerful tool for comparing rate of disease progression in subpopulations of interest. MSSS-based analysis demonstrates that African ancestry is a risk factor for a more rapidly disabling disease course.