Friday, August 29, 2008

HEALTH: Deadly Risk - Sleep Apnea

(previously published here at

University of Wisconsin-Madison researchers have found that people with severe sleep apnea are up to three times more likely to die early from the disorder, and more so if the disorder remains untreated.

Sleep apnea is a common, chronic sleeping disorder in which a person has frequent pauses in breathing, ranging from a few seconds or even minutes, often accompanied by snoring and constant waking. Normal breathing typically begins again, but sleep deprivation night after night is dangerous.

"This is not a condition that kills you acutely. It is a condition that erodes your health over time," said Dr. Michael J. Twery, director of the National Center on Sleep Disorders Research.

Published in the international journal Sleep, the 18-year study of 1,522 men and women, ages 30 to 60, confirms smaller studies that have linked an increased risk of death with sleep-disordered breathing. Eighty people died during this time - about 19 percent of whom had severe sleep apnea and only 4 percent of whom had normal sleep patterns.

According to the report, heart disease and heart-related death was tied to 26 percent of all deaths among those with normal sleep patterns and 42 percent of deaths among those who had severe sleep apnea. Other risk factors for development of the disorder include excess weight, high blood pressure, family history of the condition, being male and use of alcohol or sedatives.

Participants in the study spent one night under observation at a sleep laboratory where they were screened for sleep apnea. Those diagnosed with the disorder were divided into groups according to the severity of their condition. Severity was measured by the average number of breathing pauses and sleep disruptions. Those with normal sleep patterns constituted the baseline group.

The findings implied that risk of death was reduced when participants underwent proper treatment, such as the use of continuous positive airway pressure (CPAP), which keeps airways open during sleep and prevents pauses during breathing. There has been debate over whether to use airway pressure to treat patients who are not sleepy during the daytime.

Overall, those experiencing sleep apnea had a risk of death 3.2 times higher than those at the baseline, even after adjusting for other risk factors such as age, sex and body mass index. For participants who had untreated (non-CPAP) sleep apnea, the risk of death was 3.8 times higher.

"I was surprised by how much the risks increased when we excluded people who reported treatment with CPAP," Dr. Terry Young, Ph.D., professor of epidemiology at the University of Wisconsin-Madison, said in a news release. "Our findings suggest - but cannot prove - that people diagnosed with sleep apnea should be treated, and if CPAP is the prescribed treatment, regular use may prevent premature death."

Researchers did note that 95 percent of the study's participants were white and most had both a stable income and health care.

"It is likely that our findings may underestimate the mortality risk of [sleep disordered breathing] in other ethnic groups or the lowest socioeconomic strata where there is poor awareness and access to health care," the researchers said.

The same issue of the journal Sleep included a separate 14-year study from Australia's Woolcock Institute for Medical Research, which came to a similar conclusion, finding that individuals with severe sleep apnea have six times the risk of death as those without the disorder.

However, the number of participants in each group was significantly skewed, weakening the conclusion's impact. The study followed 380 men and women between ages 40 and 65 in Western Australia, for up to 14 years. Out of 18 people with sleep apnea, 33 percent (6 people) died; of 285 people without sleep apnea, 7.7 percent (around 22 people) died.

The U.S. study was supported by the National Institutes of Health. The Australian study was supported by the Australian National Health and Medical Research Council.

Heather J. Chin can be reached at

©The Evening Bulletin 2008

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