Is multiple sclerosis more disabling in North African patients?

Abstract

Ethnic and environmental factors are major determinant of prevalence and severity of Multiple Sclerosis (MS). Data relating to the severity of MS in North-African are scarce and conflicting and concern mainly migrants to Europe. To Answer this question, the authors have conducted a multicenter study enrolling patients with MS (Revised Mc Donald Criteria 2005) seen between 1998 and 2010 in the university hospitals of Casablanca, Fes and Marrakesh. Severity of MS was evaluated by the Progression Index (PI), time to reach an EDSS of 6.0 and the Multiple Sclerosis Severity Score (MSSS). The study included 460 patients. The sex ratio was 2.1. The mean age of MS onset was 30.2 years, with a mean follow up of 88.8 months. The relapsing-remitting MS accounted for 82.1% and the primary progressive form represented 17.9%. The median MSSS was 6.39, fast progressor (MSSS>5) represented 62.6%.The mean PI was 0.97 with 20% of Malignant forms (PI>1.2). Time to reach an EDSS score of 6 was 18 years (16.5–19.5). Previous studies comparing the MS severity between Caucasian and NA migrants in Europe have concluded to more severe disease in NA population. Our study is the first conducted in the autochthone population (Morocco) founding a similar result with a rapidly disabling disease. Subsequent Multicenter study from Algeria corroborates these findings. The Authors review and discuss possible factors and bias that could explain these data.