A 5-year prospective cohort study on health-related quality of life in patients with narcolepsy

OBJECTIVE: To evaluate the 5-year variation of health-related quality of life (HRQoL) and mood symptoms in a cohort of patients with narcolepsy.
METHODS: Adults attending the Sleep Centre of the Department of Neurological Sciences, University of Bologna in 1997 and meeting the International Classification of Sleep Disorders-Revised criteria for the diagnosis of narcolepsy were eligible. Included patients self-administered the Medical Outcome Short Form-36 (SF-36) and the Zung depression scale (ZDS) prospectively in 1998 and 2003.
RESULTS: There was no significant difference between 1998 and 2003 measures of SF-36 and ZDS in the 54 patients included. About 25% of them showed moderate or severe mood symptoms in both observations. ZDS score (inversely) and duration of disease (directly) explained a percentage of variance of role physical, vitality (VT), social functioning (SF) and role emotional. At the second observation VT and SF had a further percentage of variance explained by excessive daytime sleepiness (EDS) and age at onset. Self-reported diabetes frequency doubled after 5 years (from 7% to 17%).
CONCLUSIONS: Patients with narcolepsy show a stable impairment of HRQoL in a 5-year period with respect to Italian normative data. Mood status and EDS negatively influence their HRQoL while disease duration has a positive influence.