National Estimates of Narcolepsy in Korea

BACKGROUND AND PURPOSE: Epidemiological data on narcolepsy are rare in South Korea. We aimed to provide an overview of the burden of narcolepsy and its temporal trend in South Korea. METHODS: Patients with narcolepsy were identified by their registration in the Rare and Intractable Disease (RID) register and the Health Insurance Review and Assessment database. Individuals registered in the RID program with the code V234 were considered as having ‘definite narcolepsy’, while those who claimed health insurance with G47.4 as the primary diagnostic code were considered as having ‘probable narcolepsy’. We estimated the annual prevalence, incidence, and medical costs of narcolepsy between 2010 and 2019. RESULTS: The prevalence of definite narcolepsy was 8.4/100,000 in 2019, peaking at 32.0/100,000 in those aged 15–19 years. The prevalence was higher in males, with a relative risk of 1.72. The prevalence has increased over the past 6 years, with an average annual growth rate (AAGR) of 12.2%. The prevalence of probable narcolepsy was 10.7/100,000 in 2019. The incidence of definite narcolepsy increased up to 1.3/100,000 in 2019 with an AAGR of 7.1%. Annual medical expenditure for definite narcolepsy gradually increased up to 4.1 billion KRW in 2019, with a compound annual growth rate of 11.9%. CONCLUSIONS: This study has provided the first nationwide estimates for narcolepsy in South Korea. The prevalence of diagnosed narcolepsy in South Korea was at the low end of the range of narcolepsy prevalence rates reported for other countries. However, the prevalence and incidence have been steadily increasing over the past decade.