Obstructive sleep apnea is associated with fatty liver index, the index of nonalcoholic fatty liver disease.

Background and Objectives: 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).
Materials and Methods: 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.
Results: 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).
Conclusion: 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.