Objectives: To investigate the characteristics of two ethnic groups, African Americans (AA) and Caucasians (C), and the relationship of therapy adherence to MS relapses and disability, among patients who have completed the Therapy Optimization in MS (TOP MS) study.
Methods: Enrollees in TOP MS, a prospective, open-label, observational study, had a diagnosis of MS and received disease-modifying therapies (DMT), either glatiramer acetate (GA) or beta interferon (IFN), dispensed by a specialty pharmacy. Signed informed consents were returned to the pharmacies; study enrollment produced log-on instructions for the study website where responses were entered at regular intervals. Inclusion criteria for these analyses involved relapsing forms of MS and self-reported EDSS scores at baseline and Month 24, without simultaneous confirmed relapses. AA and C ethnic cohorts were compared using descriptive statistics and logistic regression.
Results: Of the 2,243 eligible TOP MS completers, 127 (5.7%) reported AA and 2,116 C ethnicities. There were no baseline differences in the distribution of DMT used (50.8% GA; 49.2% IFN), or prior use of another DMT (34.6%) and the reasons for change. However, the AA cohort was younger than the C cohort (mean age 46.2 vs. 50.0 years; p <0.001), experienced first MS symptoms more recently (mean 8.2 vs. 11.9 years), had a higher mean EDSS score (3.7 vs. 3.0; p < 0.0001) at baseline and was more likely to be disabled due to MS, or unemployed (p < 0.0001). The AA cohort also reported missing 40% more DMT doses each month (p < 0.001) than the C cohort. There were no significant differences between the cohorts on-study in the number of physician-confirmed relapses, proportion relapse free or change from baseline in EDSS but there were significantly fewer relapses in both ethnicities with a DMT adherence greater than 90% (p = 0.03).
Conclusions: The AA vs. C group in the TOP MS Study showed a more severe disease profile at entry and reported poorer DMT adherence during the two-year study. Although mean relapse and EDSS change on study did not differ, relapse rate was significantly less in patients with DMT adherence greater than 90%.