The utility of visceral fat area for screening nocturnal hypoxemia in non-obese subjects

<bold>Background and Objectives:</bold> Non-obese individuals are at risk of obstructive sleep apnea syndrome (OSAS) and nocturnal hypoxemia, and easily underdiagnosed. We aimed to devise a screening tool for nocturnal hypoxemia in such population. <bold>Methods:</bold> Between 2016 and 2017, non-obese subjects who were suspected of having OSAS and underwent polysomnography were enrolled. The physiological features, such as waist circumference and neck circumference, were collected, and percent of body fat and visceral fat area (VFA) were measured using InBody 770 for each participant. The association between nocturnal mean arterial oxygen desaturation (SpO2_mean) and the collected physiological variables were evaluated. <bold>Results:</bold> Of 92 participants, 30, 37, and 25 subjects were categorized into normal (body mass index (BMI) 18.9-24.9 kg/m²), overweight (BMI 25-29.9 kg/m²), and obese (BMI≧30 kg/m²) study groups, respectively. Logistic regression analysis demonstrated that each 1cm² increase in VFA was associated with a 1.1-fold higher in odds of SpO2_mean <90% (95% CI 1.022-1.097, p-value=0.001). The area under the curve, sensitivity and specificity for predicting nocturnal SpO2_mean <90% with VFA were 0.865 (an optimal cut-off of 83.7cm²), 83.3% and 76.4%, respectively. <bold>Conclusions:</bold> VFA can be used as a screening tool for nocturnal hypoxemia in normal-overweight subjects, thus to predict the risk of OSAS.