Increased mortality in narcolepsy

Objective: To evaluate the mortality rate in patients with narcolepsy.

Design: Data were derived from a large database representative of the US population, which contains anonymized patient-linked longitudinal claims for 173 million individuals.

Setting: Symphony Health Solutions (SHS) Source Lx, an anonymized longitudinal patient dataset.

Patients/participants: All records of patients registered in the SHS database between 2008 and 2010.

Interventions: None.

Measurements and results: Identification of patients with narcolepsy was based on ≥ 1 medical claim with the diagnosis of narcolepsy (ICD-9 347.xx) from 2002 to 2012. Dates of death were acquired from the Social Security Administration via a third party; the third party information was encrypted in the same manner as the claims data such that anonymity is ensured prior to receipt by SHS. Annual all-cause mortality rates for 2008, 2009, and 2010 were calculated retrospectively for patients with narcolepsy and patients without narcolepsy in the database, and standardized mortality ratios (SMR) were calculated. Mortality rates were also compared with the general US population (Centers for Disease Control data). SMRs of the narcolepsy population were consistent over the 3-year period and showed an approximate 1.5-fold excess mortality relative to those without narcolepsy. The narcolepsy population had consistently higher mortality rates relative to those without narcolepsy across all age groups, stratified by age decile, from 25-34 years to 75+ years of age. The SMR for females with narcolepsy was lower than for males with narcolepsy.

Conclusions: Narcolepsy was associated with approximately 1.5-fold excess mortality relative to those without narcolepsy. While the cause of this increased mortality is unknown, these findings warrant further investigation.