Insulin Resistance, but Not Obstructive Sleep Apnea Is Associated with Hepatic Steatosis in Chinese Patients with Severe Obesity

Abstract

Introduction Severe obesity often present with nonalcoholic fatty liver disease (NAFLD) and obstructive sleep apnea (OSA). Emerging researches suggest OSA plays an important role in NAFLD development and progression while the relationship between OSA and NAFLD is still conflicting . The interaction of OSA and NAFLD should be further evaluated as obesity surges. The purpose of this study was to assess the prevalence of OSA and NAFLD in patients with obesity undergoing bariatric surgery, and evaluate the association between OSA and severity of NAFLD. Methods 141 patients with severe obesity undergoing preoperative polysomnography and intraoperative liver biopsy during bariatric surgery was investigated. Clinical, anthropometric variables, liver enzymes, fasting blood glucose, fasting serum insulin, and homeostasis model assessment (HOMA-IR) were measured. The severity of NAFLD was assessed by degree of steatosis, ballooning, intralobular inflammation and NAFLD activity score (NAS). The diagnosis and severity assessment of OSA was based on an apnea/hypopnea index (AHI). Results OSA was diagnosed in 127 (90.07%), NAFLD in 124 (87.94%), and non-alcoholic steatohepatitis (NASH) in 72 (51.06%) patients. There was a statistically difference in body mass index (BMI), waist circumstance, neck circumstance, high-density lipoprotein-cholesterol (HDL), fasting insulin, and HOMA-IR among the three groups divided by the severity of AHI. In addition, the distribution of hepatic steatosis grades among the three groups was statistically different (P=0.025). AHI was significantly associated with HOMA-IR and hepatic steatosis when assessing the association between OSA parameters and liver histology in NAFLD(P< 0.05). Patients with steatosis of grade 1-3 had significantly elevated aspartate aminotransferase(AST), alanine aminotransferase(ALT), gamma glutamyl transferase (GGT),triglycerides (TG), fasting insulin, fasting glucose, HOMA-IR, and AHI compared with the patients with steatosis of grade 0. In a multivariable logistic analysis, the positive association between AHI and hepatic steatosis attenuated after adjusting for HOMA-IR. Conclusion Prevalence of OSA and NAFLD was high in patients with obesity eligible for bariatric procedures. HOMA-IR, but not AHI, was an independent risk factor for hepatic steatosis in this population.