Sleep apnoea a stand-alone mortality risk

An independent link between sleep apnoea and mortality has been discovered by a group of Australian researchers, suggesting the prevention and treatment of this condition should be a higher priority for government bodies working to improve community health.

The study conducted by the Woolcock Institute of Medical Research in Sydney found moderate to severe obstructive sleep apnoea (OSA) was associated with 33% mortality over 14 years compared to 7.7% mortality in people with no sleep apnea.

This is the first report to demonstrate an independent association between all-cause mortality and obstructive sleep apnea in a population-based cohort. The community-based sample of 380 people comprised men and women from the Western Australian town of Busselton who underwent investigation with a home sleep apnoea monitoring device in 1990.

The study results confirm the pattern seen in clinic or hospital-based studies where people more severely afflicted by the disease may have potentially biased results.

Dr Nathaniel Marshall, from the Woolcock Institute said the findings of the study have important implications for the direction of health policy in Australia.

“We already know that approximately 25% of men and 9% of women in the middle-age bracket in Australia stop breathing during sleep at least five times per hour,” he said.

“However because sleep apnoea is strongly associated with obesity, and its related diseases, it has been difficult in the past to produce clear evidence that increased mortality is a result of OSA and not because of other established causes.

“That evidence is now available and shows that moderate to severe sleep apnoea is associated with about five times the risk of dying after you control for other factors that are already known to cause premature death.”

Dr Marshall said the study results highlight a need to increase research funding to investigate whether treatment of sleep apnoea can decrease heart attacks, strokes and premature deaths.

“There is a need for high quality clinical trials looking at treatments for sleep apnoea that are large enough and long enough to find out whether we can prevent disease or reduce mortality risk.”

Professor Ron Grunstein, Head of Sleep and Circadian Research, Woolcock Institute said, “Obstructive sleep apnoea is a deadly disease and it is now time for public health and medical practitioners as well as the general public to take it seriously.

“The health profession needs to look closely at ways of detecting sleep apnoea in children, adolescents and young adults to prevent sleep apnea in the over 40 yrs age group.

“Sleep apnea prevention is different to obesity prevention as genetic factors related to facial shape and structure also play a role in pathogenesis,” he said.

(Source: Woolcock Institute: August 2008)