The risk of hospitalization for motor vehicle accident injury in narcolepsy and the benefits of stimulant use: A nationwide cohort study in Taiwan

Study Objectives: To examine the risk of hospitalization for motor vehicle accident injury (MVAI) in patients with narcolepsy and the effects of stimulant use on MVAI occurrence in patients with narcolepsy. Methods: This is a population-based, retrospective cohort study using Taiwan’s National Health Insurance Research Database between 2000 and 2013. We included patients with narcolepsy based on the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes, 347. The case and matched control participants were selected in a ratio of 1:3, and the traffic accident (ICD-9-CM codes: E810–E819) plus injury codes (ICD-9-CM codes: 800.xx–999.xx) due to MVAI following hospitalization were used for the study outcome. The type of injury, causes, intentionality, and the effects of stimulant use on patients with narcolepsy were also assessed. Results: A total of 1,316 participants were enrolled, including 329 participants with narcolepsy and 987 participants without narcolepsy. During a 14-year follow-up period, a total of 104 participants had MVAI, of whom 47 (1,559.54 per 100,000 person-years) belonged to the narcolepsy cohort and 57 (556.21 per 100,000 person-years) to the non-narcolepsy cohort. After adjusting for covariates, the risk of hospitalization for MVAI among participants with narcolepsy was still significantly higher than those without narcolepsy (adjusted hazard ratio = 6.725; 95% confidence interval = 4.421–10.231; P < .001). The use of modafinil or methylphenidate, as monotherapy or combined treatment, was associated with a lower risk of MVAI in the narcolepsy cohort. Conclusions: Patients with narcolepsy may have a higher risk of hospitalization for MVAI and stimulant use could mitigate such risk.