Chronic intermittent hypoxia contributes to non-alcoholic steatohepatitis progression in patients with obesity

Background and purpose The association between the severity of obstructive sleep apnea (OSA) and non-alcoholic fatty liver disease (NAFLD) in patients with obesity remains unclear. We conducted this study to determine the effects of OSA on the severity of NAFLD in individuals with obesity and its link to the development of non-alcoholic steatohepatitis (NASH). Methods Patients were subjected to standard polysomnography up to 1 week before undergoing bariatric surgery, during which liver biopsy specimens were obtained. The apnea–hypopnea index (AHI) obtained by polysomnography was used to determine the severity of OSA. Results In total, 183 patients with obesity and biopsy-confirmed NAFLD were included; 49 (27%) had NASH. Patients with NASH had higher AHIs ( p = 0.014) and oxygen desaturation indices ( p = 0.031), more frequent OSA ( p = 0.001), and lower minimum oxygen saturation ( p = 0.035). The severity of OSA was directly correlated with the NAFLD activity score ( p < 0.001), NASH activity grade ( p < 0.001), semi-quantitative indices of lobular inflammation ( p = 0.001), and hepatocyte ballooning ( p = 0.006). The odds ratios (95% confidence intervals) for NASH and severe NASH (activity grade ≥ 3) associated with moderate-to-severe OSA were 3.85 (1.35–10.94; p < 0.05) and 5.02 (1.66–15.18; p < 0.01), respectively, after adjusting for sex, age, body mass index, waist circumference, insulin resistance values, and metabolic syndrome. Conclusions Chronic intermittent hypoxia caused by OSA may aggravate NAFLD and lead to a higher risk of NASH in patients with obesity.