Health-related quality of life in Italian patients with narcolepsy: the SF-36 health survey.

OBJECTIVE: To evaluate the psychometric performances of the 36-item short form (SF-36), a tool measuring health-related quality of life (HRQoL) in patients with narcolepsy or other sleep disorders, presenting excessive daytime sleepiness (EDS) as the main symptom. To compare the HRQoL of patients with narcolepsy with the Italian norm. To disclose the clinical predictors influencing the HRQoL.

PATIENTS AND METHODS: One hundred and eight adults with narcolepsy, 115 with obstructive sleep apnea syndrome (OSAS) and 42 with idiopathic hypersomnia (IH) enrolled for a multicentric cross-section study employing self-administered questionnaires investigating the HRQoL (SF-36), EDS and cataplexy. A psychometric analysis and the standardized scoring of the 8 scales of the SF-36 were performed. The correlation between SF-36 scales and clinical features of narcolepsy was measured by a multiple linear regression analysis.

RESULTS: SF-36 satisfied the recommended psychometric standards. Patients with narcolepsy had all domains except Bodily Pain lower than the Italian norm. Some of the variance of Physical Functioning (R(2) 0.07), Role functioning-Physical (R(2) 0.31), General Health (R(2) 0.15), Vitality (R(2) 0.10), Social Functioning (R(2) 0.21) and Role functioning-Emotional (R(2) 0.15) was explained both by EDS (inverse correlation) and disease duration (direct correlation).

CONCLUSIONS: The SF-36 form is a reliable outcome measure for hypersomniac disorders. Narcolepsy seriously impacts patients' HRQoL in terms of physical and mental well-being and impairs physical and emotional functions, restricting social life. EDS is the main symptom determining this impairment. However, disease duration plays a role in counterbalancing this feature, probably by means of adaptation.