Sleep apnea is associated with an increased risk of death, according to new results from a multi-year observational study conducted by U.S. researchers.

Researchers found that adults with sleep apnea at the start of the study were two to three times more likely to die from any cause compared with those who did not have the sleep breathing disorder.

The risk of death was linked to the severity of sleep apnea and was not attributable to age, gender, body mass index or cardiovascular health status.

The results were published Friday in the journal Sleep.

Researchers followed 1,522 generally healthy men and women for an average of 13.8 years after testing them for sleep apnea using a standard overnight sleep test.

Participants with severe sleep apnea were three times more likely to die during the study than those without breathing problems during sleep. Participants with untreated severe sleep apnea were four times more likely to die from any cause and five times more likely to die from cardiovascular conditions.

The findings suggest that the treatment of severe sleep apnea may be protective, especially against cardiovascular deaths, said the researchers. Further studies are needed to determine how treatment may improve survival, quality of life, and the overall health status of affected individuals.

An estimated 12-18 million Americans have moderate to severe sleep apnea. Periodically during sleep, the upper airway becomes narrowed or blocked, and air has trouble reaching the lungs; in some cases, breathing stops completely for seconds to minutes at a time.

The frequent pauses in breathing disrupt sleep and prevent adequate amount 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.

(Xinhua News Agency August 2,2008)