Disease Progression and Therapy Response Vary in MS by Ethnicity

Randy Dotinga

March 11, 2021

Multiple sclerosis (MS) affects Whites, African Americans, and Hispanics differently, a new study finds, and there are big gaps in how they respond to disease-modifying therapies (DMTs).

"Hispanics and African Americans develop a more severe disease course and accumulate more MS-related disability over time despite similar sociodemographic backgrounds and similar patterns of DMT use throughout their disease, suggesting that socioeconomic status and access to health care may not be the main determinants of health," said neurologist Carlos Pérez, MD, of the University of Texas Health Science Center, Houston. He spoke at the annual meeting held by the Americas Committee for Treatment and Research in Multiple Sclerosis and in a follow-up interview.

"In addition," Pérez said, "therapeutic responses to individual DMTs, as well as tolerance and side-effect profiles, are also variable among racial/ethnic groups."

The researchers tracked 150 patients with MS at the University of Texas Health Science Center – 50 Whites, 50 African American, and 50 Hispanic – who were age and gender matched. The average age of the subjects was 45, and 74% of those in each group were women.

While educational levels between the groups were similar, African Americans had a much higher rate of lost employment because of disability (38%) than Hispanics (19%) and Whites (15%, P = .02). Fifty-seven patients (38%) needed escalation of therapy, and 63% were African American.

About 30% of subjects switched DMTs because of intolerance/adverse events, and 47% of those were African American. Interferons most commonly caused adverse effects in African Americans (61%), and Whites were the most likely to not tolerate glatiramer acetate (39%) than Hispanics (8%) and African Americans (13%).

What might be behind the disparities? "It is possible that genetic factors may play a greater role than previously thought. A recent study reported that Hispanic and African American patients with MS have higher levels of peripheral blood plasmablasts, which may provide indirect evidence for potential biological mechanisms underlying racial and clinical disparities in MS," Pérez said. "These mechanisms appear to involve higher degrees of inflammation in the central nervous system. This may explain why African Americans may respond better to higher-efficacy therapies initially, when inflammatory processes predominate MS-related pathology, rather than at later stages of the disease when inflammation plays a less prominent role. Neurologists should consider higher-efficacy DMT as first line. We have begun to do this in our practice."

Pérez said the findings offer other lessons. "Neurologists should consider that Caucasian patients tolerate glatiramer acetate less frequently, compared with other racial groups, and potentially consider using alternative DMTs unless the benefits outweigh the risks, such as during pregnancy."

He also noted that African Americans treated with oral DMTs at baseline were more likely to develop worsening disability over time. "This argues in favor of infusion therapies as first-line treatment," he said, adding that more Hispanics with MS were not on treatment – or discontinued treatment – compared with Whites and African Americans.

Close Patient Monitoring Is Key

Atlanta-area neurologist Mitzi Joi Williams, MD, who was asked to comment on the study findings, said in an interview that it "adds to the body of real-world evidence to assist understanding of MS in minority populations."

She noted that African American patients who started on infusions appeared to be more stable. "There are a great deal of questions surrounding starting patients on injectables versus higher-efficacy therapy initially to prevent disability and this may lend credence to the need for closer examination of initial therapy for these patients. It is important to closely monitor patients and consider a switch in DMT if there is any clinical or radiologic progression, especially for African American and Hispanic patients since there is a great deal of data to suggest they may have more aggressive disease."

Moving forward, more research like this is needed, she said. "Patients did all have insurance and were largely educated, but there could be other social determinants of health – i.e., transportation, lapses in insurance, or technology barriers – that may have led to worse outcomes."

No study funding was reported, and Pérez reported no disclosures. Williams disclosed research support from EMD Serono, Genentech, and Novartis and advisory committee/consultant relationships with AbbVie, Biogen Idec, Bristol-Myers Squibb, EMD Serono, Genentech, Novartis, and Sanofi Genzyme.

This article originally appeared on MDedge.com, part of the Medscape Professional Network.

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