The relationship between obstructive sleep apnea (OSA) and nonalcoholic fatty liver disease (NAFLD) is gaining increased attention. The aim of the present study was to examine the relationship of OSA with NAFLD defined by an elevated fatty liver index (FLI).
A total of 319 consecutive patients who underwent standard polysomnography were enrolled. Fasting blood samples were obtained from all patients for biological profile measurements, and demographic data were collected. Values of FLI were determined and assessed as predictors of the presence of NAFLD, as measured by ultrasound. The discriminative ability of FLI was estimated on the basis of the area under the receiver operator characteristic curve.
An FLI of 60 achieved the highest diagnostic accuracy and yielded an area under the receiver operator characteristic curve of 0.822 (95% confidence interval: 0.729–0.916) in the detection of NAFLD. Patients with an FLI of 60 or higher had a significantly lower lowest O2 saturation (73 vs. 83%, P<0.001), a lower mean nocturnal oxygen saturation (93 vs. 95%, P<0.001), a higher apnea–hypopnea index (39.7 vs. 18.4, P<0.001), a higher oxygen desaturation index (39 vs. 10.6, P<0.001), and a higher percentage of sleep time spent with SpO2 less than 90% (4.63 vs. 0.92%, P<0.001) compared with those with FLI less than 60. In multivariate analysis, the presence of OSA was independently associated with elevated FLI after adjusting for confounding factors (odds ratio: 5.141, 95% confidence interval: 1.414–18.696, P=0.013).
Our results suggest a positive association between the severity of OSA and NAFLD defined by an elevated FLI, which may serve as a good biomarker for detecting NAFLD in OSA patients.
aDepartment of Intensive Care Unit
bLaboratory of Respiratory Disease of the Fujian Medical University, Department of Respiratory Medicine, Fujian Provincial Sleep-disordered Breathing Clinic Center, the First Affiliated Hospital of Fujian Medical University, Fuzhou
cDepartment of Respiratory Medicine, Hospital of Integrated Traditional Chinese and Western Medicine, Southern Medical University, Guangzhou
dDepartment of Respiratory Medicine, Zhangzhou Affiliated Hospital of Fujian Medical University, Zhangzhou, China
* Xiao Chen and Xian Lin contributed equally to the writing of this article.
Correspondence to Qi-Chang Lin, MD, NO 20, Chazhong road, Taijiang district, Fuzhou, Fujian Province, China Tel: +86 59 187 981 697; fax: +86 59 187 981 697; e-mail: firstname.lastname@example.org
Received November 17, 2015
Accepted January 11, 2016