Circadian-rhythm differences among emergency department patients with chronic obstructive pulmonary disease exacerbation.

The purpose of the study was determine whether patients with chronic obstructive pulmonary disease (COPD) exacerbation who present to the emergency department (ED) during the night (00:00 to 07:59 h) vs. other times of the day have more severe COPD exacerbation, require more intensive treatment, and have worse clinical outcomes. A multicenter cohort study was completed involving 29 EDs in the United States and Canada. Using a standard protocol, consecutive ED patients with COPD exacerbation were interviewed, and their charts were reviewed. Of 582 patients enrolled, 52% were women, and the median age was 71 yrs (interquartile range, 64-77 yrs). Nighttime patients (15% of cohort) did not differ from patients presenting at other times except that they were less likely to have private insurance, more likely to have a history of corticosteroid use, and have a shorter duration of symptoms exacerbation. Except for a few features indicative of more severe COPD exacerbation (such as higher respiratory rate at ED presentation, greater likelihood of receiving noninvasive positive pressure ventilation, and increased risk of endotracheal intubation), nighttime patients did not differ from other patients with respect to ED management. Nighttime patients were approximately three-fold more likely to be intubated in the ED (odds ratio, 3.46; 95% confidence interval, 1.10-10.9). There were no day-night differences regarding ED disposition and post-ED relapse. Except for some features indicating more severe exacerbation, nighttime ED patients had similar chronic COPD characteristics, received similar treatments in the ED, and had similar clinical outcomes compared with patients presenting to the ED at other times of the day.