MS and Disability Progression in Latin America, Africa, Asia and the Middle East: A Systematic Review.

ABSTRACT

BACKGROUND: There is evidence of an increased prevalence and disease burden of Multiple Sclerosis (MS) in parts of the world where the risk was once considered low, such as Latin America (LA), Sub-Saharan Africa, Asia and the Middle East-North Africa (MENA). Despite the growing number of clinical reports, the phenotype and course of MS in these regions remains understudied compared with Europe and North America. We aimed to investigate MS phenotypes and long-term clinical outcomes across these regions. METHOD: A Boolean search of the medical literature was conducted between January 1980 and April 30, 2020. PubMed, SCOPUS, Global Health, and the Cochrane databases, were used to identify all relevant citations. Articles were collated and managed on Covidence® software. We independently appraised the articles for meeting study criteria and for quality using the Critical Appraisal Skills Program (CASP) and the Specialist Unit for Review Evidence (SURE) system. RESULTS: A total of 1,639 studies were imported for screening. After removing 545 duplicates, two authors assessed 1,094 abstracts and selected 515 for full-text screening. 72 articles met study criteria, including 19 studies from LA, 4 from sub-Saharan Africa, 24 from Asia and 25 from MENA. The overall sex ratio was 2.51 (female male). Disability was assessed using the Expanded Disability Status Scale (EDSS). Longitudinal disability progression and time to standard endpoints was compared by region and with relevant Western reports. Patients with MS living in the MENA region appear to reach disability milestones faster than those in the Western world, although this finding is not uniform. South Asia shows distinct disability features compared with East Asia, more closely resembling those of the West. Disease morbidity in East Asia appears more benign than in the West after careful exclusion of neuromyelitis optica spectrum disorder cases. Populations in LA tend to have similar MS features to the Western world, but some exceptions exist, including African descendants that reach disability milestones earlier. Using all studies with appropriate survival analysis, the mean time to EDSS 6.0 was 16.97 years with a heterogeneity index of 24.59. CONCLUSION: The clinical phenotypes and disability progression of MS in LA, Africa, Asia and the MENA region have similarities to Western MS. In some regions and subpopulations there is evidence of a more aggressive course, possibly due to a combination of genetic and environmental factors. More population-based longitudinal data are needed, particularly in Sub-Saharan Africa.