Effects of Sleep on Health-Related Quality of Life in Patients With Coronary Heart Disease
Sleep problems have been associated with a wide range of adverse health outcomes and are common in patients with coronary heart disease (CHD). Even though research working with these patients has frequently used the Pittsburgh Sleep Quality Index (PSQI) as a self-report measure to assess sleep quality, its factor structure has yet to be validated in this population. Therefore, the first aim of this study is to examine the factor structure of the PSQI in CHD patients. Additionally, this study also investigated both the cross-sectional and longitudinal relationships between sleep and health-related quality of life. Participants in the study included 167 patients with CHD enrolled in a cardiac rehabilitation program, and 109 of them also completed follow-up assessments three months later. Results from the confirmatory factor analysis revealed that the proposed two-factor structure with sleep efficiency and perceived sleep quality best fitted the data. Subsequent analyses using structural equation modelling found that sleep quality, but not sleep efficiency, significantly predicted emotional, physical, and social quality of life. Sleep quality was also found to predict physical and social quality of life, but not emotional quality of life, three months later. These findings demonstrated the usefulness of assessing sleep in terms of its dimensions, and that improving sleep quality is key to enhancing quality of life in cardiac patients.