Association between obstructive sleep apnea and liver steatosis investigated by magnetic resonance imaging

Background and Aims: Obstructive sleep apnea (OSA) and nonalcoholic fatty liver disease (NAFLD) are frequently encountered in overweight and obese patients. Whether OSA is associated with liver steatosis investigated by magnetic resonance imagery (MRI), a robust and non-invasive physical marker of liver steatosis in a large cohort of patients suspected for OSA is unknown. Methods: 167 nondrinking patients with nocturnal polysomnographic recording for clinical suspicion of OSA were included in the study. Liver steatosis evaluation was performed by measuring the proton density fat fraction (PDFF) which is the fraction of MRI visible protons bound to fat divided by all protons in the liver. Significant liver steatosis was defined as a PDFF ?6.5%. Results: 11(6.5%) patients had no OSA, 31 (18.6%) had mild OSA, 56 (33.5%) had moderate OSA and 69 (41.3%) had severe OSA. 79 (47.3%) patients had a PDFF values ?6.5%. On univariate analysis, severe OSA (AHI ?30 events/h) was associated with a significantly increased risk of a PDFF ?6.5% (OR 2.04, 95% CI 1.09–3.80) but the association was not maintained after adjusting for confounders including age, gender, triglycerides level and body mass index (OR 1.27, 95%CI 0.63–2.56). Conclusions: Severe OSA is associated with increased liver steatosis but the association is not maintained after adjusting for confounders including BMI.