Global Prevalence of Neuromyelitis Optica Spectrum Disorder: A Systematic Review and Meta-Analysis with New Data from...

Neuromyelitis optica spectrum disorder (NMOSD) is a rare autoimmune astrocytopathy with geographic and ancestral variability in prevalence. Despite growing international epidemiological evidence, population-based prevalence studies of NMOSD remain scarce in Brazil.

The aim of the study was to integrate global evidence from a systematic review and meta-analysis with new regional prevalence data from southeastern Brazil using complementary epidemiological and statistical methods.

A systematic review was conducted to identify studies reporting crude NMOSD prevalence between 2000 and 2025. In parallel, a multi-source prevalence study was performed in the Volta Redonda-Barra Mansa intermediate region of Rio de Janeiro State. Crude prevalence, classical two-source capture-recapture estimators, and Bayesian modeling were applied. A random-effects meta-analysis combined international estimates with Brazilian data and compared pooled results across continents.

We identified 44 eligible studies from 28 countries, with substantial heterogeneity reflecting differences in diagnostic criteria, case-ascertainment strategies, and geographic coverage. Crude NMOSD prevalence ranged from 0.23 to 10.0 per 100,000 inhabitants. In the Brazilian regional study, 24 confirmed cases among 782,004 inhabitants yielded a crude prevalence of 3.07 per 100,000, with capture-recapture estimates ranging from 3.53 to 5.60 per 100,000 and Bayesian posterior mean estimates of 3.84-3.87 per 100,000. The global meta-analysis produced a pooled prevalence of 2.02 per 100,000 inhabitants, with continent-specific differences: the Americas showed the highest prevalence, followed by Asia, Europe, and Oceania.

This study provides an integrated evaluation of NMOSD prevalence through a global systematic review, a regional population-based analysis in southeastern Brazil, and a meta-analysis, demonstrating that prevalence in this region is higher than the global pooled estimate and consistent with the higher prevalence observed in the Americas, particularly in populations with substantial African ancestral backgrounds.