Supplementary Material for: Sleep Duration and Its Associations with Mortality and Quality of Life in Chronic Obstructive Pulmonary Disease: Results from the 2007–2015 KNAHNES

Background: While extreme sleep duration negatively affects mortality and health-related quality of life (HRQOL) in general populations, the relationship remains uncertain in patients with chronic obstructive pulmonary disease (COPD). Objectives: To evaluate the association between sleep duration and mortality and HRQOL in patients with COPD. Methods: We analyzed 3,349 participants with COPD enrolled in the 2007–2015 Korea National Health and Nutrition Examination Survey (KNHANES). Participants aged 40 years or older with a smoking history and prebronchodilator forced expiratory volume in 1 s/forced vital capacity (FEV1/FVC) <0.7 were eligible. The participants were categorized as short sleepers (<6 h), 6–8 h, and long sleepers (>8) according to self-reported sleep duration. The outcome variables were all-cause mortality and HRQOL. HRQOL was measured using the European Quality of Life-5 Dimensions (EQ-5D) index. Results: During a median of 6.5 years, 386 (11.5%) participants died. In unadjusted Cox regression analysis, short sleepers with COPD had an increased risk of death (hazard ratio, 1.35; 95% confidence interval [CI]: 1.07–1.71). However, this association was not significant after adjusting for sociodemographic factors, BMI, FEV1, and comorbidities. In unadjusted and adjusted multiple linear regression, short sleepers had significantly worse HRQOL. The adjusted means of the EQ-5D index were 0.88 (95% CI: 0.87–0.89) for short sleepers, 0.90 (95% CI: 0.90–0.91) for 6- to 8-h sleepers, and 0.89 (95% CI: 0.87–0.91) for long sleepers (p = 0.01). Conclusions: In patients with COPD, sleep duration was not associated with all-cause mortality. However, short sleep duration was significantly associated with worse HRQOL.