Relationship between quality of life and mood or depression in patients with severe obstructive sleep apnea syndrome

Study objectives: To assess the quality of life (QOL) in patients with severe obstructive sleep apnea (OSAS), and the relationship between the QOL and severity of OSAS, excessive daytime sleepiness (EDS), and mood. Methods: Sixty patients with OSAS and 34 normal control subjects were assessed for QOL using the Medical Outcomes Study Short-Form 36 Health Survey questionnaire (SF-36), for EDS using the Epworth sleepiness scale (ESS), and for mood using the Zung self-rated depression scale (SDS). The associations between each domain and the total score on the SF-36 and the baseline characteristics, polysomnographic parameters, ESS score, and SDS score were examined by simple regression analysis and stepwise multiple regression analysis. Results: Six of eight domains and the total score on the SF-36 were significantly lower than those in the control subjects. The ESS and SDS scores were also more impaired in the patients than in the control subjects. There was no relationship between each domain on the SF-36 and the severity of OSAS and ESS score. Five of eight domains and the total score on the SF-36 were significantly correlated with the SDS score. Stepwise multiple regression analysis selected three variables, the SDS score (partial R-2 = 0.505), the lowest arterial oxygen saturation during sleep (partial R-2 = 0.064), and ESS score (partial R-2 = 0.053), as independent factors for predicting the total score on the SF-36. These three variables accounted for 62.2% of the total variance in the total score on SF-36 (R-2 = 0.622, p < 0.0001) Conclusions: The QOL of patients with severe OSAS was decreased compared with normal control subjects. The QOL of patients was strongly correlated with the depression scale on simple regression analysis. However, EDS score and oxygen desaturation during sleep also affected the QOL, although the magnitude of its effect was small.