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Sleep apnea linked to increased risk of death

August 04, 2008

Sleep-disordered breathing (also known as sleep apnea) is associated with an increased risk of death, according to new results from the Wisconsin Sleep Cohort, an 18-year observational study supported by the National Heart, Lung, and Blood Institute (NHLBI) of the National Institutes of Health. Researchers found that adults (ages 30 to 60) with sleep-disordered breathing at the start of the study were two to three times more likely to die from any cause compared to those who did not have sleep-disordered breathing. The risk of death was linked to the severity of sleep-disordered breathing and was not attributable to age, gender, body mass index (an indicator of overweight or obesity), or cardiovascular health status.

"Sleep-Disordered Breathing and Mortality: Eighteen-Year Follow-Up of the Wisconsin Sleep Cohort," is published August 1 in the journal Sleep.

Researchers followed 1522 generally healthy men and women for an average of 13.8 years after testing them for sleep-disordered breathing using a standard overnight sleep test. Participants with severe sleep-disordered breathing were three times more likely to die during the study than those without breathing problems during sleep. Those who were not treated were at even greater risk. Participants with untreated severe sleep-disordered breathing were four times more likely to die from any cause and five times more likely to die from cardiovascular conditions.

The Wisconsin Sleep Cohort is the most comprehensive assessment yet of mortality risks associated with sleep-disordered breathing and the first to study a randomly selected population of adults in the United States. The findings suggest that the treatment of severe sleep-disordered breathing may be protective, especially against cardiovascular deaths. Further studies are needed to determine whether the findings are applicable across the United States, and how treatment may improve survival, quality of life, and the overall health status of affected individuals.

Michael J. Twery, PhD, director of the NHLBI National Center on Sleep Disorders Research, is available to comment on these findings, as well as on associated health risks of sleep-disordered breathing, and the importance of diagnosing and treating the condition.

An estimated 12-18 million Americans have moderate to severe sleep-disordered breathing. Periodically during sleep, the upper airway becomes narrowed or blocked, and air has trouble reaching the lungs; in some cases, breathing stops completely (called apnea) for seconds to minutes at a time. The frequent pauses in breathing disrupt sleep and prevent adequate amounts of oxygen from entering the bloodstream. Interruptions in breathing are potentially serious medical conditions and should be evaluated by a physician to determine whether treatment is needed.

Because affected individuals are asleep and typically unaware of the breathing problems, and the condition cannot be diagnosed during routine physician office visits, most people with sleep-disordered breathing are undiagnosed.

Untreated sleep-disordered breathing has been linked to a greater risk of cardiovascular disease and risk factors - including high blood pressure, stroke, and diabetes -- as well as to excessive daytime sleepiness, which can impair quality of life and performance on the job or in school, and increase the risk of injury or death from work-related accidents and vehicular crashes.

Common signs that should be discussed with a physician include complaints of snoring from bed partners, excessive daytime sleepiness, and morning headache. Sleep-disordered breathing occurs in people of all ages, but is more common in men, the elderly, and overweight individuals. With the growing prevalence of overweight and obesity in the United States and the aging population, the number of individuals with sleep-disordered breathing is likely to rise.

NIH/National Heart, Lung and Blood Institute