Hypoxic Burden of Sleep Apnea Predicts CVD Mortality

Study Questions:

Is sleep apnea severity predictive of mortality among adults aged ≥40 years?

Methods:

Data from two cohort studies (MrOS [Outcomes of Sleep Disorders in Older Men] and the SHHS [Sleep Heart Health Study]) were used for the present analysis. MrOS is a community-based prospective cohort of 5,994 men aged ≥65 years recruited from six centers in the United States between 2000 and 2002. Men who completed an ancillary sleep study in 2005 and were not using continuous positive airway pressure (CPAP) or a similar device were eligible for the present analysis. SHHS is a community-based prospective cohort study of 6,441 men and women aged ≥40 years with baseline exams in 1995-1998. The primary exposure of interest was hypoxic burden determined by measuring the respiratory event-associated area under the desaturation curve from pre-event baseline. Outcomes of interest were all-cause and cardiovascular disease (CVD)-related mortality. Mean follow-up was 10 ± 3.5 years in MrOS and 10.9 ± 3.1 years in SHHS.

Results:

For the present analysis, 2,743 men, aged 76.3 ± 5.5 years from MrOS and 5,111 men and women (52.8% women), aged 63.7 ± 10.9 years from SHHS were included. A total of 440 CVD-related deaths and 1,270 all-cause deaths were identified in MrOS, and 313 CVD-related deaths and 1,142 all-cause deaths were identified in SHHS. The hypoxic burden predicted CVD mortality, while prediction of all-cause mortality was only observed in MrOS. Individuals in the MrOS study with hypoxic burden in the highest two quintiles had hazard ratios of 1.81 (95% confidence interval [CI], 1.25–2.62) and 2.73 (95% CI, 1.71–4.36), respectively. The SHHS group with hypoxic burden in the highest quintile had a hazard ratio of 1.96 (95% CI, 1.11–3.43).

Conclusions:

The investigators concluded that hypoxic burden, an easily derived signal from overnight sleep study, predicts CVD mortality across populations. The findings suggest that not only the frequency but the depth and duration of sleep-related upper airway obstructions are important disease characterizing features.

Perspective:

These data support the importance of CVD prevention including an assessment of sleep apnea. These results suggest that hypoxic burden may be particularly important.

Clinical Topics: Heart Failure and Cardiomyopathies, Prevention, Sleep Apnea

Keywords: Airway Obstruction, Cardiovascular Diseases, Continuous Positive Airway Pressure, Hypoxia, Brain, Osteoporotic Fractures, Polysomnography, Primary Prevention, Sleep Apnea Syndromes, Sleep Disorders, Sleep-Wake Transition Disorders


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