(RxWiki News) Having one health condition can often put someone at risk for another health condition. Such is the case with obstructive sleep apnea, a common but underdiagnosed sleep disorder.
During obstructive sleep apnea, a person frequently stops breathing for at least 10 seconds at a time while asleep, or else has a decrease in breathing followed by an arousal.
The individuals were part of a 20-year study in Western Australia. The study did not find those with sleep apnea to be at a higher risk for coronary artery disease but may have been too small to show links to heart disease.
"Treat your obstructive sleep apnea."
The study, led by Nathaniel S. Marshall, PhD, of the Woolcock Institute of Medical Research at the University of Sydney in Australia, looked at whether obstructive sleep apnea was a risk factor for various chronic conditions and for death.
The researchers specifically looked at the risk of cardiovascular disease, coronary heart disease, stroke and cancer in addition to looking at the risk for death from any cause.
The researchers tracked 400 residents of a Western Australian town, all of whom underwent a sleep study at the end of 1990 and were followed through the end of 2010.
Among the group, 77 people died, 31 had strokes, 59 had coronary heart disease, and 125 had cancer — including 39 who died from cancer.
Then the researchers compared which participants had sleep apnea to those who died or had other chronic conditions.
In calculating the risks for those with obstructive sleep apnea, the researchers adjusted their analysis to take into account the following other risk factors: age, sex, obesity, smoking status, blood pressure, cholesterol levels, angina (chest pain) and diabetes.
The analysis also excluded the four people who had previously had a stroke and the seven people who had previously had cancer.
The researchers found that those with moderate-to-severe obstructive sleep apnea were four times more likely to have died during the study follow-up.
Participants with moderate-to-severe obstructive sleep apnea were also 2.5 times more likely to have cancer and more than 3 times more likely to have died from cancer.
The individuals with moderate-to-severe obstructive sleep apnea were also 3.7 times more likely to experience a stroke, but they were no more likely than other participants to have cardiovascular disease or coronary heart disease in this study.
However, according to William Kohler, MD, the director of the Florida Sleep Institute in Spring Hill, Florida, this study may have been too small, with only 400 individuals, to identify risks with cardiovascular disease as past research has shown.
"Other studies have shown very definite correlations between hypertension and sleep apnea," Dr. Kohler said. "Hypertension is considered a cardiovascular disease, so saying that there's no significant cardiovascular is not really accurate because other studies have shown association there."
Meanwhile, those who had mild sleep apnea were only slightly more likely to have died than those without (not even doubled) and were no more likely to experience the other outcomes.
These findings do not mean the sleep apnea caused stroke or cancer.
It's possible those who experienced stroke or cancer and obstructive sleep apnea shared other underlying conditions that the researchers did not take into account.
However, the findings do mean that those with obstructive sleep apnea may be at increased risk for stroke or cancer. Dr. Kohler emphasized that this study is important because it shows significant risks associated with the sleep disorder.
"This study further confirms the serious nature of obstructive sleep apnea, that we need to be aware of it, diagnose it and treat it," Dr. Kohler said.
The standard treatment for obstructive sleep apnea is continuous positive airway pressure, or CPAP.
CPAP involves wearing a mask during sleep that pushes air into a person's airways.
The study was published April 15 in the Journal of Clinical Sleep Medicine. The research was funded by the Australian National Health and Medical Research Council.
One author has received funding for a sleep apnea clinical trial from Teva Cephalon. No other conflicts of interest were reported.