Prevalence and incidence of neuromyelitis optica spectrum disorder and multiple sclerosis in Korea

Background: The epidemiology of neuromyelitis optica spectrum disorder and multiple sclerosis varies depending on the region and ethnicity. Objective: To estimate the prevalence and incidence of neuromyelitis optica spectrum disorder and multiple sclerosis in Korea during 2010–2016. Methods: We analyzed the National Health Insurance research database, which contains single-payer health insurance data collected in Korea. Neuromyelitis optica spectrum disorder was defined based on the 2006 Wingerchuk criteria (for 2010–2015), and the 2015 International Panel for Neuromyelitis Optica Diagnosis criteria (for 2016). Multiple sclerosis was defined by the 2005 International Panel criteria for multiple sclerosis. Results: In 2016, the age-standardized prevalence per 100,000 persons was 2.56 (95% confidence interval: 2.43–2.7) for neuromyelitis optica spectrum disorder and 3.23 (95% confidence interval: 3.08–3.39) for multiple sclerosis. The age-standardized incidence of neuromyelitis optica spectrum disorder and multiple sclerosis were 0.73 (95% confidence interval: 0.66–0.8) and 0.50 (95% confidence interval: 0.44–0.56) per 100,000 persons in 2016. The prevalence of neuromyelitis optica spectrum disorder and multiple sclerosis have increased over time during 2010–2016 (18.5% and 5.4% annually; both p-trend < 0.001). The incidence of neuromyelitis optica spectrum disorder increased annually (10.0%, p-trend < 0.001), while the incidence of multiple sclerosis remained stable. Conclusion: While the prevalence of neuromyelitis optica spectrum disorder and multiple sclerosis are comparable in Korea, the incidence of neuromyelitis optica spectrum disorder is higher than that of multiple sclerosis. Both the prevalence and incidence of neuromyelitis optica spectrum disorder are rapidly increasing in Korea.