In Sleep Apnea, Length of Abnormal Breathing Events Affects Mortality Risk
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The shorter a person’s apneas and hypopneas, the greater risk they have of dying compared with those who experience longer apneas over the same time period, according to a new study published by the American Thoracic Society.1
To reach this conclusion, the researchers analyzed the records of 5712 adults who participated in the National Heart, Lung, and Blood Institute’s Sleep Heart Health Study and whose health was followed for up to 11 years.
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The data showed that participants with the shortest duration of apneas and hypopneas were 31% more likely to die within that 11-year period than those who had longer apneas and hypopneas.
“This result seems counter-intuitive because you might expect longer periods of not breathing to be more severe,” said Matthew P. Butler, PhD, the study’s lead author. “On the other hand, shorter periods of disturbed breathing indicate a low arousal threshold, which would associate with sleep fragmentation, elevated sympathetic tone and greater risk for hypertension.”2
The apnea-hypopnea index (AHI) has been used as a main measure of sleep apnea severity, but Butler says that index does not predict women’s mortality risk well enough. Butler and his colleagues’ finding that the duration of abnormal breathing events can predict mortality risk for both men and women.
The connection between short apneas and hypopneas was clearest among participants whose sleep apnea severity was moderate as measured with AHI. Among those participants, the ones with the shortest duration of breathing events had a 59% increased risk of dying within the 11-year follow-up period.
The researchers also looked into the role of participants’ demographics in the length of abnormal breathing events. For example, those with shorter event duration were more likely to be younger, female, African American, and current smokers.
“These data provide new information to inform emerging initiatives to identify sleep apnea subphenotypes reflective of individuals with different underlying mechanisms who may experience different outcomes and respond differently to treatments,” the researchers concluded.1
—Colleen Murphy
References:
- Butler MP, Emch JT, Rueschman M, et al. Apnea-hypopnea event duration predicts mortality in men and women in the Sleep Heart Health Study [published online October 19, 2018]. Ann Am Thoracic Soc. https://doi.org/10.1164/rccm.201804-0758OC.
- Length of each breathing disruption in sleep apnea may predict mortality risk better than number of breathing disruptions. [press release]. New York, NY: American Thoracic Society; October 19, 2018. https://www.thoracic.org/about/newsroom/press-releases/. Accessed October 18, 2018.