Objective: To examine differences in the therapeutic response to ocrelizumab in multiple sclerosis (MS) patients who self-identified as either White or Black, assessed longitudinally by expanded disability status scale (EDSS) progression and MRI brain volume loss.
Methods: MS subjects treated with ocrelizumab were retrospectively identified. Clinical data were available for 229 subjects (White 146; Black 83) and MRI data from for 48 subjects (White 31; Black 17). Outcome measures were changes in the EDSS and brain volume over time. EDSS were analyzed as raw scores, ambulatory (EDSS <5.0) vs. ambulatory with assistance (5.5 ≤ EDSS ≤ 6.5) status, and EDSS severity (< 3.0, 3.0-5.0, and > 5.5 ≤ 6.5). General linear mixed model was used for statistical analysis. FreeSurfer was used for volumetric analysis.
Results: The Black cohort had overrepresentation of females (78% vs. 62%, p = 0.013), lower age (median, 45 (IQR 39-51) vs. 49 (38-58), p = 0.08), lower Vitamin D levels (33 (21-45) vs. 40 (29-52), p = 0.002), and higher EDSS (4 (2-6) vs. 2.5 (1-6), p = 0.019). There was no progression of EDSS scores over the 2-year observation period. The covariates with significant influence on the baseline EDSS scores were older age, race, longer disease duration, prior MS treatment, and lower vitamin D levels. No differences were observed between the racial groups over time in the cortical, thalamic, caudate, putamen, and brainstem gray matter volumes nor in the cortical thickness or total lesion volume.
Conclusion: In this real-world clinical and radiological study, ocrelizumab treatment was highly effective in stabilizing clinical and MRI measures of disease progression in Blacks and Whites, despite higher baseline disability in the Black cohort.
Keywords: Brain atrophy; Expanded disability status scale; Multiple sclerosis; Ocrelizumab; Racial differences; Therapeutic response.
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