Narcolepsy is associated with an increased risk of HLA-related autoimmune diseases: Evidence from a nationwide healthcare system data in South Korea

To determine the incidence rate of narcolepsy in South Korea and closely examine the relationship between narcolepsy, which is believed to be an autoimmune response, and other systemic autoimmune diseases. We examined data from the South Korean nationwide health insurance claims database from 2010 to 2019. Our study included patients with narcolepsy as well as age- and sex-matched controls without narcolepsy. We estimated the incidence of narcolepsy and the odds ratio of narcolepsy and associated autoimmune comorbidities in South Korea. We identified 8710 patients with narcolepsy (59.8% men and 40.2% women). The incidence of narcolepsy was 0.05%. Patients with narcolepsy were at a significantly high risk of ankylosing spondylitis, rheumatoid arthritis, and Sjögren's syndrome, which diseases are known to be related to human leukocyte antigen (HLA) genes. Narcolepsy is closely related to systemic autoimmune diseases, particularly those related to HLA genes.