BACKGROUND: COPD increases susceptibility to sleep disturbances, which may in turn predispose to increased respiratory symptoms. The objective of this study was to evaluate, in a population-based sample, the relationship between subjective sleep quality and risk of COPD exacerbations. METHODS: Data were obtained from the Canadian Cohort Obstructive Lung Disease (CanCOLD) study. Participants with COPD who had completed 18 months of follow-up were included. Sleep quality was measured with the Pittsburgh Sleep Quality Index (PSQI) and a three-factor analysis. Symptom-based (dyspnea or sputum change $ 48 h) and eventbased (symptoms plus medication or unscheduled health services use) exacerbations were assessed. Association of PSQI with exacerbation rate was assessed by using negative binomial regression. Exacerbation-free survival was also assessed. RESULTS: A total of 480 participants with COPD were studied, including 185 with one or more exacerbations during follow-up and 203 with poor baseline sleep quality (PSQI score > 5). Participants with subsequent symptom-based exacerbations had higher median baseline PSQI scores than those without (6.0 [interquartile range, 3.0-8.0] vs 5.0 [interquartile range, 2.0-7.0]; P ¼ .01), and they were more likely to have baseline PSQI scores > 5 (50.3% vs 37.3%; P ¼ .01). Higher PSQI scores were associated with increased symptombased exacerbation risk (adjusted rate ratio, 1.09; 95% CI, 1.01-1.18; P ¼ .02) and event-based exacerbation risk (adjusted rate ratio, 1.10; 95% CI, 1.00-1.21; P ¼ .048). The association occurred mainly in those with undiagnosed COPD. Strongest associations were with Factor 3 (sleep disturbances and daytime dysfunction). Time to symptom-based exacerbation was shorter in participants with poor sleep quality (adjusted hazard ratio, 1.49; 95% CI, 1.09-2.03). CONCLUSIONS: Higher baseline PSQI scores were associated with increased risk of COPD exacerbation over 18 months' prospective follow-up.

Mechanical ventilation with high tidal volumes was associated with increased mortality in patients with congestive heart failure and post cardiac arrest in our CICU.

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