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Clinical characteristics of multiple sclerosis (MS) patients, including their response to therapies, vary based on race and ethnicity, new research shows.
The findings were presented at the Americas Committee for Treatment and Research in Multiple Sclerosis (ACTRIMS) Forum 2021 by Carlos A. Pérez, MD, a MS fellow at The University of Texas Health Science Center at Houston. The presentation’s title was “Patterns of Disease-Modifying Treatment Use and Sociodemographic Characteristics in Multiple Sclerosis by Race and Ethnicity.”
Phase 3 clinical trials are the gold standard for determining the effectiveness of potential therapies. However, in MS, these trials have historically enrolled white participants disproportionately. Minority enrollment in Phase 3 MS studies has remained below 10% since the 1990s, according to Pérez.
While African Americans and Hispanics are generally thought to be at lower risk of developing MS than Caucasians of European descent (whites), emerging data suggests that people in these groups are at a greater risk of disability. These differences, combined with the poor representation in clinical trials, limit the extent to which efficacy data for treatments can be generalized to different groups.
To shed light on this matter, Pérez and colleagues conducted a study to “compare patterns of disease-modifying therapies (DMT) use by race and ethnicity, and to characterize select sociodemographic and clinical characteristics between Hispanic, African American, and Caucasian MS patients followed in a large academic center.”
The team analyzed clinical, socioeconomic, and disability data for 150 people with MS who were treated at their institution, the University of Texas Health Science Center in Houston: 50 Hispanics, 50 African Americans, and 50 Caucasians. The three groups were matched in terms of age and gender (mean age 44.9 years, 72% female).
African Americans had significantly lower levels of vitamin D at baseline. No other significant differences between the groups were noted in terms of time to diagnosis, disease duration, smoking, body mass index (BMI), or comorbidities (health problems other than MS).
In all three groups, educational attainment was similar, with most patients having completed college. Compared to the other groups, African Americans were more likely to be unemployed (42% vs. 28% in Hispanics and 22% in Caucasians) and to become disabled (38% vs. 19% in Hispanics and 15% in Caucasians).
“Despite the similar levels of education … African Americans were more likely to become disabled and to lose employment, compared to Hispanics or Caucasian MS patients over time,” Pérez said.
At initial diagnosis, about 74% of patients in all three groups had minimal disability. However, this changed over time.
“Twice as many Hispanic patients (20%) and African Americans (18%) had substantial disability … compared to Caucasian MS patients (8%) on their most recent [disability assessment], despite similar rates of [disease] progression over time,” Pérez said.
Across the groups, individuals with lower educational attainment or with comorbidities (including hypertension and diabetes) were more likely to experience worsening disability over time.
Among African Americans, patients treated with oral therapies as their first treatment were more likely to experience disability progression over time, whereas those given an infusion therapy as their first treatment were less likely to experience greater disability over time. However, African Americans given an infusion therapy as their second or third treatment were more likely to experience disability progression.
This observation “is important, because it might suggest that it’s beneficial to start maybe an infusion therapy in the African American population from the beginning, rather than later on when disability has already accumulated,” Pérez said.
A total of 57 patients required escalation therapy, which means they moved from a less effective medication to a more effective one. The majority of these patients (62.9%) were African American.
Although there were some differences between the groups in which exact therapy patients who escalated were switched, Pérez said that differences in treatment probably do not explain the differences in disability between the groups, since all were switched to more effective therapies.
The most common reasons for switching therapies were disease progression and intolerance (i.e., side effects). Of 45 patients who switched due to intolerance, nearly half (46.7%) were African American.
African American patients were particularly likely to experience adverse reactions to interferon therapies (such as Avonex, Rebif, and Betaseron), while Caucasian patients were less likely to tolerate glatiramer acetate treatment.
Compared to the other groups, “although fewer Hispanic patients switched DMT over time, they were more often not on any treatment,” and “more of them were actually lost to follow-up,” Pérez said — about 10% lost to follow-up vs. 2% in Caucasians and 4% in African Americans.
In all three groups, patients treated with Ocrevus (ocrelizumab) were less likely to switch to a different treatment over time. Also, patients with minimal disability treated with Aubagio (teriflunomide) were less likely to switch to another therapy.
Overall, Pérez concluded there are “disparities in sociodemographic and clinical characteristics of patients with MS,” and that “therapeutic responses to individual treatments are also variable among racial/ethnic groups.”
“Increasing our understanding of how race and ethnicity might affect one’s response to therapy might help us understand better how to treat these patients,” Pérez added. “For this reason, minority representation should be increased in future MS clinical trials, in order to improve the accuracy of clinical data and evidence-based treatment guidelines.”
Pérez also noted that, based on these disparities, “individualized approaches to therapy based on race- and ethnicity-dependent patterns of DMT use/response might potentially help decrease the burden of MS-related disability in underrepresented minority groups.”
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