Research Article: Sleep-Disordered Breathing and Mortality: A Prospective Cohort Study

Date Published: August 18, 2009

Publisher: Public Library of Science

Author(s): Naresh M. Punjabi, Brian S. Caffo, James L. Goodwin, Daniel J. Gottlieb, Anne B. Newman, George T. O’Connor, David M. Rapoport, Susan Redline, Helaine E. Resnick, John A. Robbins, Eyal Shahar, Mark L. Unruh, Jonathan M. Samet, Anushka Patel

Abstract: In a cohort of 6,441 volunteers followed over an average of 8.2 years, Naresh Punjabi and colleagues find sleep-disordered breathing to be independently associated with mortality and identify predictive characteristics.

Partial Text: Sleep-disordered breathing is being increasingly recognized as a cause of substantial morbidity and mortality. Characterized by recurrent collapse of the upper airway, sleep-disordered breathing is associated with recurrent episodes of intermittent hypoxemia and arousals from sleep. Approximately 9% of women and 24% of men in the general population have sleep-disordered breathing and a majority of those affected remain undiagnosed [1]. In addition to causing excessive daytime sleepiness and impaired quality of life [2], sleep-disordered breathing has been implicated in increasing all-cause and cause-specific mortality. Evidence from clinic-based studies suggests that patients with sleep-disordered breathing have a higher mortality risk and that treatment with positive airway pressure during sleep may attenuate this risk [3]–[19]. However, previous studies based on clinical samples have yielded inconsistent results, possibly due to methodological limitations including small sample sizes and use of select patient samples. Furthermore, some of the earlier studies failed to adequately consider potential confounding by obesity and factors such as prevalent hypertension and cardiovascular disease. Recent data from two population-based cohort studies with modest sample sizes have shown that even after accounting for such confounders, sleep-disordered breathing is independently associated with all-cause mortality [20],[21].

The analysis cohort included 6,294 participants (53.3% women), which excluded 147 who reported treatment with positive airway pressure, an oral appliance, supplemental oxygen, or an open tracheostomy after the baseline visit. As expected, older age, male sex, minority race, BMI, and central adiposity were associated with increasing severity of sleep-disordered breathing (Table 1). Among men, 42.9% did not have sleep-disordered breathing, 33.2% had mild disease, 15.7% had moderate disease, and 8.2% had severe disease. In women, the corresponding percentages were 64.7%, 24.5%, 7.9%, and 3.0%, respectively. Prevalent hypertension, diabetes, and cardiovascular disease were more common in individuals with moderate to severe sleep-disordered breathing than those with mild or no sleep-disordered breathing. In total, the cohort accumulated 51,523 person–years of observation with an average follow-up duration of 8.2 y. Of the analysis cohort, 1,047 participants (460 women) died during follow-up, yielding a crude mortality rate of 20.3 deaths per 1,000 person-years (95% CI: 19.1–21.6). Men had a higher mortality rate than women (24.8 versus 16.5 per 1,000 person-years, p<0.0001; χ2 = 42.3) despite similar age and BMI distributions. Mortality rates per 1,000 person–years in the full cohort varied with the AHI category as follows: no sleep-disordered breathing (16.8; 95% CI: 15.4–18.4), mild disease (21.7; 95% CI: 19.4–24.2), moderate disease (28.3; 95% CI: 24.3–33.0), and severe disease (32.2; 95% CI: 26.0–39.8). Using a prospective cohort study, which included middle-aged and older adults from several United States communities, we examined the independent association between sleep-disordered breathing and mortality. The results of this study demonstrate that, independent of several confounding variables, sleep-disordered breathing was associated with all-cause and cardiovascular disease–related mortality. The association was most apparent in men aged 40–70 y with severe disease (AHI≥30 events/h). The degree of sleep-related hypoxemia was found to be independently associated with mortality, whereas the arousal frequency and the central sleep apnea index were not. Source: http://doi.org/10.1371/journal.pmed.1000132

 

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