Abstract
Aim: No previous research has assessed the epidemiology or treatment of narcolepsy in New Zealand. This study aimed to estimate its national incidence and prevalence and examine demographic trends in the prescribing of narcolepsy-related medications.
Method: From 2021 to 2023, diagnostic data from all centres conducting multiple sleep latency tests (MSLTs) were analysed to estimate incidence and prevalence. Concurrently, data on all special authority (SA) approvals for narcolepsy medications were obtained from Pharmac and analysed by medication type, region, age, gender and ethnicity.
Results: Among 342 MSLTs, 57 cases of narcolepsy were identified, giving an incidence of 0.36 per 100,000 person-years and a prevalence of 21.9 per 100,000 people. Over the same period, 223 new and 762 total SA applications were approved. The average number of new approvals (74.3 per year) was 3.9 times higher than the number of new diagnoses (19 per year). Demographic variations were observed in the SA data. Generally, methylphenidate hydrochloride was prescribed more than modafinil.
Conclusions: This is the first national estimate of the incidence and prevalence of narcolepsy in New Zealand. The mismatch between diagnosis and treatment data likely reflects limited diagnostic access, multiple medication use, the existence of imported cases with established diagnoses and the treatment of idiopathic hypersomnolence (IH) under the guise of narcolepsy. Policy and funding changes are needed to improve care access and reporting accuracy.