Prevalence, incidence, and medications of narcolepsy in Japan: a descriptive observational study using a health insurance claims database.

The objectives of this study were to describe prevalence, incidence, and medications among patients who were diagnosed with narcolepsy in Japan using a claims database. Patients diagnosed with narcolepsy were identified from January 2010 to December 2019 using an employment-based health insurance claims database compiled by JMDC Inc. The prevalence and incidence of narcolepsy were estimated annually in the overall population and by age and sex among employees and their dependents aged < 75 years. Medications, examined for each quarter in the overall population, were modafinil, methylphenidate, pemoline, tricyclic antidepressants, selective serotonin reuptake inhibitors, and serotonin-norepinephrine reuptake inhibitors. We identified 1539 patients with narcolepsy. The overall annual prevalence increased from 5.7 to 18.5/100,000 persons in 2010 and 2019, respectively. Large increases were found from 2010 to 2019 in patients aged 20-29 years and 10-19 years, with the highest prevalence in 2019 (9.7-37.5/100,000 persons and 5.0-27.1/100,000 persons). The overall incidence slightly increased from 3.6 to 4.3/100,000 person-year from 2010 to 2019, and the highest incidence was found in patients aged 20-29 years and 10-19 years (5.8-11.3/100,000 person-year, and 3.8-7.4/100,000 person-year from 2010 to 2019, respectively). Methylphenidate and modafinil were commonly prescribed in 2010 (27.3-38.9% and 17.5-45.5%, respectively). Methylphenidate prescriptions declined during the 10 years, whereas modafinil prescriptions increased (15.6-17.1% and 43.8-45.8% in 2019, respectively). The estimated prevalence and incidence of narcolepsy appeared to increase from 2010 to 2019, especially in teenagers and 20-year olds. Supplementary Information: The online version contains supplementary material available at 10.1007/s41105-022-00406-4.