The prevalence and incidence of narcolepsy in the United States: a real-world observational study using a validated narcolepsy case definition

Study Objectives Narcolepsy is a chronic condition affecting the sleep/wake cycle that is challenging to diagnose. Epidemiological data from large US-focused studies remain limited, with no validated claims-based case selection definitions for narcolepsy. We estimated the prevalence/incidence of diagnosed narcolepsy (type 1 [NT1], type 2 [NT2], overall) in an insured US population using validated, claims-based narcolepsy case definitions. Materials and Methods This observational study used HealthVerity administrative claims-linked electronic medical records to develop case definitions identifying individuals with NT1, NT2, and overall narcolepsy from diagnosis, medication, and procedure codes. Claims-based case definition performance (NT1, NT2, overall narcolepsy) was assessed using positive predictive values (PPVs). Prevalence (per 100 000 persons, on December 31, 2023) and annual incidence (per 100 000 person-years [PY], 2020 − 2023) were calculated/adjusted using PPVs for each case definition. Results Unadjusted point prevalence among individuals with ≥12 months of continuous enrollment were 15.5/100000 (NT1), 51.1/100000 (NT2), and 67.0/100000 (overall narcolepsy). Unadjusted incidence rates were stable from 2020 − 2023 for NT1 (range, 2.0 − 2.3/100000 PY) but declined across years for NT2 (9.1 − 7.6/100000 PY) and overall narcolepsy (11.3 − 9.6/100000 PY). PPVs (95% confidence interval) of NT1, NT2, and overall narcolepsy were 0.81 (0.72 − 0.88), 0.84 (0.75 − 0.91), and 0.80 (0.71 − 0.87), contributing to epidemiologic estimates being reduced by ~20% after PPV adjustment. Prevalence and incidence were higher in females than males. Individuals with NT1 were ~ 4 years younger versus NT2. Conclusions Validated definitions for narcolepsy can reduce potential misclassification. Our findings highlight a relatively low NT1 prevalence in the US. In contrast, NT2 prevalence estimates were > 3 times higher than NT1.