New Stroke Risk Factor: Sleep Apnea
Death, Stroke Risk Doubles With Obstructive Sleep Apnea
Nov. 9, 2005 -- Sleep apnea can cause fatal strokes, a new study shows.
As many as one in four men and one in 10 women have obstructive sleep apnea -- abnormal breathing in which the throat closes over and over again during sleep. In its mild forms, it causes industrial-strength snoring. As it becomes more serious, a person finds it very hard to stay awake during the day.
Sleep apnea is linked to heart disease. It's also linked to stroke. But it's never been clear whether sleep apnea causes stroke or the other way around. Now it is, report Yale researcher H. Klar Yaggi, MD, MPH, director of the VA Connecticut sleep laboratory, and colleagues.
Yaggi's team looked at more than 1,000 people seeking medical help for nighttime breathing problems. Two-thirds of these age-50-or-older people turned out to have sleep apnea; some, but not all, chose to be treated.
"Those patients with obstructive sleep apnea had about a twofold increased risk of stroke or dying compared to those without sleep apnea," Yaggi tells WebMD. "Those with more severe obstructive sleep apnea had threefold risk of stroke or death from any cause -- and that was after adjusting for other stroke risk factors."
The findings appear in the Nov. 10 issue of The New England Journal of Medicine. So does a commentary by Virend K. Somers, MD, PhD, professor of medicine and consultant in cardiovascular disease at the Mayo Clinic in Rochester, Minn.
"This is the best data so far implicating sleep apnea as a probable cause of stroke," Somers tells WebMD.
Can Sleep Apnea Treatment Save Lives?
The Yaggi study was not designed to test the effects of treatment. But it raises questions about how well doctors treat patients with obstructive sleep apnea.
"The problem is these patients were being treated in different ways. And even though they were treated, their risk of stroke was very high," Somers says. "This could mean, gosh, if they weren't being treated, their risk of stroke would have been even higher. Or it could mean that treatment was not as good as it could be in preventing stroke."
Yaggi says there's a strong suggestion that treatment did help.
"We think perhaps the risk would have been even greater if those people had not gotten treated," he says. "But the design of our study was not such that we could draw any conclusions about the impact of therapy. That is the next study that needs to be done."
There's no argument that sleep apnea treatment can get quick results in treating many of the symptoms of obstructive sleep apnea. Treatment not only helps snoring and daytime drowsiness, but it also reduces the high blood pressure caused by sleep apnea, says David M. Rapoport, MD, director of the sleep medicine program at New York University. Rapoport was not involved in the Yaggi study.
"Maybe it takes a long time to accumulate the effects of treatment, and even though patients get better they may not eliminate the stroke risk right away," Rapoport tells WebMD. "There is a cumulative effect of sleep apnea. It is like smoking. If you smoke for 20 years and then stop, you are at higher risk of lung cancer for a while."