The study also showed that men aged 30 to 39 have three times the risk of dying, while those in their forties have twice the risk. But those aged 50 or older don't have a higher risk of dying than the same age group in the general population.
"We were surprised to find a sharp decline in the risk of dying after age 50," says lead researcher Professor Peretz Lavie of the Lloyd Rigler Sleep Apnea Research Laboratory at the Technion-Israel Institute of Technology.
"Older patients have more risk factors, especially cardiac ones, so we expected relative mortality to increase with age," he notes. "The fact that they don't suggests that patients with sleep apnea develop a mechanism, as yet unknown, that protects their cardiovascular system."
In light of these findings, Lavie recommends a change in sleep apnea testing guidelines. Currently, patients seek help only when their symptoms become noticeable and disturbing, and the average age of sleep clinic patients is around 50. Lavie believes screening should be conducted not only for twenty somethings with sleep apnea symptoms, but also for other groups known to have a high prevalence of sleep apnea " even if they do not have characteristic symptoms. These include the young obese, people who developed hypertension at a young age or children of sleep apnea sufferers. Diagnosing and treating sleep apnea at an early age, he says, would lower fatalities.
According to Lavie, sleep apnea testing could be conducted using outpatient facilities, and tests could be made available for home use by patients, encouraging patients to be diagnosed and treated accordingly. He is careful to point out that sleep apnea patients who are older than 50 should still be treated, as such treatment will improve their condition and quality of life, and reduce the risks of automobile and work-related accidents.
Sleep apnea is characterized by interruptions in breathing during sleep that last 10 seconds or more, at least five times per hour. They cause repeated interruptions of sleep and decreased oxygen levels in the blood, and have been linked with cardiovascular diseases, especially hypertension. The condition affects up to 10 percent of adult men, who in most cases are not aware that their breathing stops during sleep but who complain of chronic fatigue, excessive sleepiness, tendency to doze off during the day and loud, intermittent snoring.
The study, which appears in the March 2005 European Respiratory Journal, was based on the largest population of sleep apnea patients (nearly 15,000 men) ever to be studied. All were recorded in the Technion sleep clinics in Israel from 1991 through 2000. The researchers compared the risk of dying for men with severe sleep apnea -- having at least 50 breathing stops per hour -- with the general population.
The Technion-Israel Institute of Technology is Israel's leading science and technology university. Home to the country's only winners of the Nobel Prize in science, it commands a worldwide reputation for its pioneering work in computer science, biotechnology, water-resource management, materials engineering, aerospace and medicine. The majority of the founders and managers of Israel's high-tech companies are alumni. Based in New York City, the American Technion Society is the leading American organization supporting higher education in Israel, with 17 offices around the country.
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European Respiratory Journal (Mar-2005)