Ethnic and Socioeconomic Associations with Multiple Sclerosis Risk

Epidemiological research in multiple sclerosis (MS) has mainly been performed in socioeconomically and ethnically limited populations; influences on MS risk have not been studied in prospectively collected non-White populations. We set out to study the influence of previously described MS risk factors in an ethnically diverse population.

A nested case-control study was created using primary care records of >1 million individuals, >50% of whom identify as Black, Asian, and Minority Ethnic (BAME). MS cases were compared to an age- and sex-matched control cohort (1:4), and to a large unmatched cohort. Odds ratios (ORs) of disease were determined according to exposure of interest, and a multivariate model including all exposures was created. Potential pairwise interactions were considered where both indicated a significant effect.

A total of 1,344 confirmed MS cases were included. MS OR in blacks aged <40 years was 1.15 (95% confidence interval [CI] = 0.81-1.62) compared to whites. MS odds in BAME current (OR = 1.71, 95% CI = 1.24-2.31) and ex-smokers (OR = 2.83, 95% CI = 2.14-3.72) were considerably higher than in Whites (OR = 1.09, 95% CI = 0.88-1.34; OR = 1.44, 95% CI = 1.19-1.74, respectively). Prior infectious mononucleosis was associated with increased odds of MS in Blacks (OR = 4.94, 95% CI = 1.23-17.89). An increase in MS odds was seen in the least-deprived quintile (OR = 2.46, 95% CI = 1.40-4.24), but no effect across deprived quintiles was seen.

This cohort provides novel data on factors potentially driving MS susceptibility in a diverse population, one-third of whom live in poverty. Environmental exposures have differential risk across ethnicity. ANN NEUROL 2020;87:599-608.