Black Americans Suffer Greater Multiple Sclerosis Disease Burden Than Whites

Black Americans with multiple sclerosis (MS) have more severe indicators of clinical disability and pathological disease than their white counterparts, even after adjusting for measures of socioeconomic status. However, MS-related disability in Black Americans (BAs) is less dependent on socioeconomic indicators than for white Americans (WAs). These findings from an analysis of a multicenter database including 8,744 Americans with MS were recently published in Neurology by a team of researchers from the participating U.S. centers.

“This large cross-sectional study confirmed observations in our practices and in the literature that Black Americans tend to have more severe MS,” says study author Daniel Ontaneda, MD, PhD, a neurologist with Cleveland Clinic’s Mellen Center for Multiple Sclerosis Treatment and Research. “It also provided intriguing insights at the intersection of disease and social determinants of health.”

Indicators of racial discrepancies in MS

Evidence has been emerging that BAs fare worse with MS than WAs. But existing studies for the most part have been limited by being retrospective, small or based on semi-quantitative outcome scales. In addition, the role of socioeconomic status in MS has not been well described. This study aimed to address some of those data gaps.

Study design and results

Participants were drawn from the Multiple Sclerosis Partners Advancing Technology Health Solutions (MS PATHS) network, a database sponsored by Biogen that includes seven MS centers in the U.S., including Cleveland Clinic.

Clinical factors (including self-reported disability and objective neurologic function assessments) and imaging measures were compared between 1,214 self-identified BAs (14%) and 7,530 self-identified WAs (86%). Adjustments were made for age, sex, disease subtype and duration, treatment, body mass index, smoking status and socioeconomic indicators (education, employment and insurance).

Findings included statistically significant differences in the following areas:

• Clinical disability. BAs had worse disability outcomes compared with WAs in several clinical measures, including self-reported disability, cognitive processing speed, walking speed and manual dexterity.
• Imaging findings. BAs had more brain MRI lesions and lower overall and gray matter brain volumes, including reduced thalamic, cortical and deep gray matter volumes, compared with WAs.
• Demographic and socioeconomic. BAs were likelier than WAs to be younger, disabled or unemployed, as well as to have Medicaid insurance and a lower education level. Lower socioeconomic indicators correlated with worse neuroperformance scores and MRI findings in WAs, but these trends were not as clear in BAs.

“Considering that socioeconomic status is linked with poor health outcomes in many diseases, it was surprising that this association, although evident among white Americans, was not found among Black Americans,” observes study co-author Kedar Mahajan, MD, PhD, of Cleveland Clinic’s Mellen Center.

Additionally, the analysis revealed that BAs were more likely than WAs to be currently treated with higher-efficacy (infusion) medications.

More-nuanced study needed

The multicenter researchers note that their study provides novel and confirmatory evidence that BAs generally fare worse with MS than WAs, a difference that held true for inflammatory and neurodegenerative measures as well as neurological performance. The reasons for this difference remain unclear and are worth investigating further, the authors write. They recommend the following directions for future study:

• Increase racial diversity in MS clinical trials. In addition to conducting more racially representative clinical trials, it might be useful to conduct studies that specifically focus on BAs, for example, to help determine whether more aggressive early treatment can mitigate later disability.
• Focus on social determinants of health in longitudinal studies. Factors such as systemic racism may also play a measurable role in health outcomes, and identifying their impacts may ultimately help to shape optimal treatment strategies, the researchers observe. For example, one could conclude that genetic differences might explain why BAs have worse disability despite the fact that they are likelier to be treated with higher-efficacy MS medications. On the other hand, bias-related undertreatment of blacks early in their disease course could potentially be to blame.

“Factors related to systemic racism may explain outcomes in ways that are not easy to measure, especially in a relatively short-duration study,” notes Dr. Ontaneda. “We suspect that social determinants of health that have yet to be identified are likely contributors to some of the differences observed in this study.”

“The partnerships we have with MS PATHS allow for continued assessment of determinants of clinical disability using real-world observational data,” adds Dr. Mahajan. “These studies also trigger basic science questions into identifying mechanisms that could discriminate differences in neurodegeneration and/or repair mechanisms between cohorts of patients.”