Fast multiple sclerosis progression in North Africans: Both genetics and environment matter.

Abstract

To compare multiple sclerosis (MS) disability progression among North Africans (NAs) living in France (NAF) and in Tunisia (NAT) and Caucasian patients born and living in France (CF). Patients with MS admitted to the day hospital in the Neurology Department at Pitié-Salpêtrière Hospital (France) and Razi Hospital (Tunisia) were questioned on their place of birth and the place of birth of their parents. To compare delay to outcomes, log-rank tests were used. Univariate and multivariate Cox models were used to determine factors influencing time to Expanded Disability Status Scale (EDSS) 6. We consecutively included 462 patients: 171 CF, 151 NAT, and 140 NAF. Sex ratio, disease forms, and delay from disease onset to diagnosis were similar between the groups. NAF differed from other groups, with a shorter median time to reach EDSS 3, 4, and 6, and a more frequent incomplete recovery after first relapse (<i>p</i> < 0.0001). Furthermore, the NA second-generation group showed the youngest median age at onset (26.5 ± 8.8 years, <i>p</i> = 0.001), the shortest median time to EDSS 6 in relapsing-remitting patients, and an increased mean number of relapses during the first 5 years of the disease (6.1 ± 3.7, <i>p</i> = 0.01) compared to CF. The Cox proportional hazard models demonstrate that (1) NA ethnicity is a significant predictor of fast progression even when adjusting for major covariates and (2) treatment did not influence the models. Our study further supports severity of MS in NAs and unravels the particular severity in NAs living in France, mainly for the second generation.