Sleep Apnea Boosts Death Risk
But it's unclear whether treating the breathing disorder cuts the danger, one expert says
FRIDAY, Aug. 1, 2008 (HealthDay News) -- The interrupted nighttime breathing of sleep apnea appears to increase the risk of dying, Australian researchers report.
Earlier studies have linked sleep apnea to increased risk for death. However, these studies were done in sleep centers rather than in the general community. This new study suggests that the risk is present among all people with obstructive sleep apnea.
"This is the first study to demonstrate an independent association between all-cause mortality and sleep apnea in a community-based study," researcher Nathaniel Marshall, a postdoctoral fellow at the Woolcock Institute of Medical Research in Sydney, said in an American Academy of Sleep Medicine news release.
"The size of the increased mortality risk was surprisingly large," Marshall said. "In our particular study, a sixfold increase means that having significant sleep apnea at age 40 gives you about the same mortality risk as somebody aged 57 who doesn't have sleep apnea," he said.
Sleep apnea is a common problem in which one has pauses in breathing or shallow breaths during sleep.
The report was published in the Aug. 1 edition of Sleep.
For the study, Marshall's team collected data on 380 men and women, 40 to 65 years old, who participated in the Busselton Health Study. That study is an ongoing survey of residents in the rural town of Busselton in the state of Western Australia.
Among these people, three had severe obstructive sleep apnea, 18 had moderate sleep apnea, and 77 had mild sleep apnea. The remaining 285 people did not suffer from the condition.
During 14 years of follow-up, about 33 percent of those with moderate to severe sleep apnea died, compared with 6.5 percent of those with mild sleep apnea and 7.7 percent of those without the condition, Marshall's group found.
For patients with mild sleep apnea, the risk of death was not significant and could not be directly tied to the condition, the researchers note.
"Our findings ... remove any reasonable doubt that sleep apnea is a fatal disease," Marshall said. "People who have, or suspect that they have, sleep apnea should consult their physicians about diagnosis and treatment options."
Dr. David M. Claman, director of the Sleep Disorders Center at the University of California, San Francisco, believes this study strengthens the conclusion that severe obstructive sleep apnea does contribute to cardiovascular illness and death.
"This Australian data has additional strengths in that it is a population-based prospective sample with a long period of follow-up," Claman said.
However, the researchers could not assess whether there were any beneficial effects of a common apnea treatment called Continuous Positive Airway Pressure, Claman said. Continuous Positive Airway Pressure (CPAP) treatment blows air into a person's nose to keep the airway from collapsing.
"Further work is needed to see if mild obstructive sleep apnea is associated with adverse effects and if Continuous Positive Airway Pressure treatment reduces cardiovascular risk in larger populations," he said.
In another report in the same issue of the journal, researchers from the University of Wisconsin uncovered findings similar to those in Australia.
In the Wisconsin study, researchers found severe sleep apnea was associated with a threefold increased risk of dying. In addition, for those with moderate to mild sleep apnea, the risk of death was increased 50 percent compared with people without sleep apnea. However, this increased risk was not statistically significant, the researchers report.
"Our findings of significant mortality risk with untreated sleep disordered breathing, in conjunction with prior evidence that Continuous Positive Airway Pressure can effectively treat severe sleep disordered breathing, underscore the immediate need for heightened clinical recognition and treatment of sleep disordered breathing," the researchers concluded.
For more about sleep apnea, visit the U.S. National Library of Medicine.