Self-reported sleep quality and acute exacerbations of chronic obstructive pulmonary disease

BACKGROUND Many patients with chronic obstructive pulmonary disease (COPD) suffer from poor sleep quality. We hypothesized that poor sleep quality in otherwise stable patients predicted exacerbations in these patients. METHODS This is a secondary analysis of the results of a previously published randomized trial of azithromycin in 1,117 patients with moderate to severe COPD who were clinically stable on enrollment. Sleep quality was measured using the Pittsburgh Sleep Quality Index. Other quality of life indices included the Medical Outcome Study 36-item Short Form Health Survey and the St Georges Respiratory Questionnaire. Outcomes included time to first exacerbation and exacerbation rate. RESULTS Sleep quality was "poor" (Pittsburgh Sleep Quality Index >5) in 53% of participants but was not related to age or severity of airflow obstruction. Quality of life scores were worse in "poor" sleepers than in "good" sleepers. Major classes of comorbid conditions, including psychiatric, neurologic, and musculoskeletal disease, were more prevalent in the "poor" sleepers. Unadjusted time to first exacerbation was shorter (190 versus 239 days) and exacerbation rate (1.7 versus 1.37 per year) was greater in the poor sleepers, but no differences were observed after adjusting for medications and comorbid conditions associated with poor sleep. CONCLUSION Poor sleepers had greater exacerbation rates than did good sleepers. This appeared to be due largely to them having more, or more severe, concomitant medical conditions and taking more medications.