Narcolepsy and risk of traumatic injury: a population-based matched cohort study.

Study objectives: We evaluated the risk of traumatic injury in patients with narcolepsy compared to the general population.

Methods: We conducted a population-based matched cohort study using a Japanese health insurance claims database. For each patient with narcolepsy, up to 5 individuals from the general population without narcolepsy were matched by variables such as sex, age, and cohort entry month. The primary outcome was traumatic injury, and the secondary outcome was fracture. The study population was followed for up to 5 years from the cohort entry date. We estimated crude incidence rates, adjusted incidence rate differences, adjusted hazard ratios, and their 95% confidence intervals (CIs) for study outcomes using crude and multivariable Poisson and Cox regression models.

Results: We included 2,451 patients with narcolepsy (mean age, 30.3 years; male, 58.0%) and 10,591 matched individuals (mean age, 30.6 years; male, 58.4%). Crude incidence rate of traumatic injury was 11.4 per 100 person-years for patients with narcolepsy compared with 6.2 per 100 person-years for matched individuals (adjusted incidence rate difference, 6.2 excess events per 100 person-years [95% CI, 4.9-7.4]; adjusted hazard ratio, 1.8 [95% CI, 1.5-2.2]). Crude incidence rate of fracture was 2.3 per 100 person-years for patients with narcolepsy compared with 1.3 per 100 person-years for matched individuals (adjusted incidence rate difference, 1.2 excess events per 100 person-years [95% CI, 0.7-1.7]; adjusted hazard ratio, 1.7 [95% CI, 1.4-2.1]).

Conclusions: Narcolepsy was associated with increased risk of traumatic injury. For patients with narcolepsy, optimized approaches to injury prevention should be considered.

Citation: Zheng Y, Fukasawa T, Masuda S, Takeuchi M, Kawakami K. Narcolepsy and risk of traumatic injury: a population-based matched cohort study. J Clin Sleep Med. 2024;20(10):1657-1662.