Epidemiological Study on Multiple Sclerosis in Brazil: Demographic and Clinical Characteristics According to Geographic Distribution – a BRANDO study

Introduction: Multiple Sclerosis (MS) is an inflammatory and neurodegenerative disorder. The prevalence of MS varies across Brazil (15 to 18 per 100,000 in average - South: 27 per 100,000) and the absence of an extensive national study limits the epidemiological understanding of MS in a nation as diverse as Brazil.

Objective: to describe the epidemiological differences among people with MS across four Brazilian regions.

Methods: Data from 2974 MS patients in the Collaborative Latin American Database for Multiple Sclerosis (BRANDO) were analysed. We assessed demographic (sex, ethnicity) and clinical outcomes (age at onset, disability status, relapse frequency and topography, MS phenotype, initial treatment) to elucidate regional differences.

Results: The cohort was predominantly female (72.5%) with MS onset age of 30.6 years. Ethnicity: Caucasian (75.8%), Mixed – Pardo/Mulato (18.5%), African descent (5.3%), and Asian (0.4%). Relapse topography involved the optic nerve (48.8%), brain (51.4%), posterior fossa (37.6%), and spinal cord (53.6%). Relapsing-Remitting (RR) was the most common phenotype (81.0%). Natalizumab (18%) and Beta-interferon 1A (10.4%) were the most prevalent initial treatments. Regional differences: Lower predominance of female (68.7%, p=.003) in the Southeast; Higher Mixed ethnicity (p=.000), 40.3% and 63.7%, in the Central-West and Northeast, respectively; Differences (p=.000) in number of relapses (Southeast [1.6] = Northeast [1.5]> South [.98] > Central-West [.51]); Higher EDSS score in Northeast (4.0, p=.000) compared to all other regions (mean range, 2.6 – 3.2); Higher prevalence of RR in the Southeast and Central-West (87%, p<.001), while the Northeast presented (p<.001) the highest rates of Primary Progressive (15.8%) and Secondary Progressive MS (18%). Glatiramer Acetate (19.7%) was the prevalent initial treatment in Northeast compared to Natalizumab (15% - 21%) in the others regions. Conclusions: Marking Brazil's first extensive MS cohort study, our findings underscore regional epidemiological variations, advocating for tailored approaches in MS management and research.