Impaired Endothelial Function in Persons With Obstructive Sleep Apnea: Impact of Obesity
Does obstructive sleep apnea (OSA) contribute to endothelial dysfunction independent of obesity?
Seventy-one subjects were recruited from a population-based study in Norway. Subjects were categorized as obese (body mass index [BMI] ≥30 kg/m2), nonobese (BMI <30 kg/m2) with OSA (apnea–hypopnea index [AHI] ≥10), or nonobese without OSA (AHI <5). Endothelial function was measured by brachial artery ultrasound and expressed as percentage of flow-mediated dilation (FMD%).
Endothelial function was found to be impaired in subjects with OSA compared to nonobese subjects without OSA (FMD%; 6.4 ± 3.2 vs. 10.1 ± 6.3; p = 0.003). FMD% did not differ between obese (6.0 ± 3.4) and nonobese (6.7 ± 3.1) OSA subjects (p = 0.3). AHI, BMI, gender, and baseline brachial artery diameter were significantly associated with FMD%. In a multivariate model, only AHI was significantly associated with FMD%.
The authors concluded that OSA is associated with endothelial dysfunction independently of obesity and conventional risk factors.
OSA has been previously associated with cardiovascular disease (CVD); however, the relationship between OSA and CVD is confounded by obesity and other associated risk factors. Although a continuous positive airway pressure intervention arm would have been highly informative, this study lends support to a causal relationship between OSA severity and impaired endothelial function. The mechanisms responsible for this relationship will require further study.
Keywords: Body Mass Index, Norway, Continuous Positive Airway Pressure, Obesity, Sleep Apnea Syndromes
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