RESUMO
BACKGROUND: There is a scarcity of information on the prevalence of demyelinating diseases in Chile and other Latin American countries. The aim of this study was to determine the prevalence of multiple sclerosis (MS) and neuromyelitis optica spectrum disorder (NMOSD) in a region of central-northern Chile. METHODS: A cross-sectional study was performed. All patients in the region with a confirmed diagnosis of MS or NMOSD under control of the program by the end of 2020 and were included in the study, totalling sixty patients with a diagnosis of MS and eight patients with NMOSD. Sociodemographic and clinical variables for these patients were recorded by the neurologists in charge of the MS programs at each public and private facility in the Coquimbo region between January and March of 2021. RESULTS: The prevalence of MS was 7.18 per 100,000 inhabitants (95% CI: 5.36â8.99) and NMOSD, 0.95 per 100,000 population (95% CI: 0.9â1.62). Both diseases were several times more prevalent in women than in men (female/male ratio: MS, 5:1 and NMOSD, 7:1). The mean age at diagnosis was 32.2 for MS and 32.2 years for NMOSD. No relevant risk factors were identified. In terms of the type of MS, 86.6% patients had a diagnosis of relapsing-remitting MS, 6.7% had primary progressive MS, and 6.7% had secondary progressive MS. Overall, 20% of patients with MS and 12.5% with NMOSD presented score over 5 in the Expanded Disability Status Scale, and 87.5% of the NMOSD patients were receiving rituximab. CONCLUSION: The prevalence of demyelinating diseases in a central-northern region of Chile corresponds to the reported rates for other Latin American countries. This is an important contribution, given the scarcity of evidence on the prevalence of demyelinating diseases in Chile. These illnesses mainly affect young adult women and are a cause of disability among productive adults.