Obstructive Sleep Apnea Doubles Sudden Death Risk

A new meta-analysis summarizes the dangers posed sleep apnea, which include a doubling of the risk of sudden death from cardiac causes. It is still unclear whether continuous positive airway pressure (CPAP), one of the main treatments for obstructive sleep apnea, lowers that risk.

A new meta-analysis is helping to clarify the health consequences of obstructive sleep apnea (OSA), finding that people with the condition have nearly double the risk of sudden death.

The study, published in BMJ Open Respiratory Research, highlights the life-threatening consequences of the OSA, which by some estimates affects more than 1 billion people worldwide and up to 15% of adults in the United States.

A number of factors associated with OSA have negative implications for the lives of patients. The poor sleep quality from OSA can lead to daytime sleepiness and lower quality of life. Several cardiovascular problems, including coronary heart disease, are more common in people with OSA. And patients with high apnea-hypopnea index scores — a measure of OSA severity — have been shown to have a three-fold increase in risk of all-cause mortality.

The co-author of the meta-analysis, Paddy Ssentongo, M.D., Ph.D., M.P.H., an assistant research professor at Penn State, says OSA’s grim implications are not always appreciated by the public.

“Apart from disturbing their partner’s sleep from snoring, the public has not grasped the danger of sleep apnea,” Ssentongo tells Managed Healthcare Executive.® “Like most clinical conditions that do not cause pain, sleep apnea has not yet gained the attention it deserves.”

Although a growing body of evidence has shown OSA can lead to major negative health implications, the risk of sudden death specifically is not well characterized. Existing studies have been inconclusive or contained insufficient evidence to draw broad conclusions. In hopes of changing that, Ssentongo and colleagues constructed a meta-analysis and review of more than 22 observational studies that collectively comprised a study population of 42,000 participants from 5 continents. The goal was to see how OSA affected risk of mortality in general, and cardiovascular mortality in general.

The study population had an average age of 62, and most (64%) of the study volunteers were men. The data showed OSA led to a heightened risk of all-cause sudden death and almost doubled cardiovascular mortality.

A dose-response relationship was identified between OSA severity and risk of death, though the investigators said the effect was only marginally significant. On the other hand, older age was found to be a significant contributing factor to risk, with older patients facing higher mortality.

The reasons for increased mortality are not fully understood, but Ssentongo and colleagues wrote that intermittent hypoxia and oxygen desaturation during sleep can arouse the central nervous system and increase both systolic and diastolic blood pressure during sleep, which can increase cardiovascular risk. They added that sustained oxidative stress associated with OSA has been linked with the development of atherosclerosis and endothelial dysfunction.

Ssentongo says the new meta-analysis helps put in context the importance of preventing obstructive sleep apnea prevention.

“First, we know what prevents the majority of sleep apnea, and we should pay more emphasis on the prevention of sleep apnea than its treatment,” Ssentongo says. “Public health intervention geared toward weight loss, particularly reduction in abdominal obesity, can prevent some cases of sleep apnea.”

Screening also plays a key role, he says. Physicians need to actively initiate conversations about sleep apnea and begin interventions and management promptly when patients are diagnosed with the condition. Yet, he adds that more research needs to be done to see what effect treatments like continuous positive airway pressure (CPAP) therapy have on mortality risk.

“Importantly, although we know that CPAP significantly reduces snoring, daytime sleepiness and improves health-related quality of life, the data on the effect of CPAP on death from cardiovascular causes is still not clear,” he says.