Prevalence and predictors of asymptomatic liver disease in patients undergoing gastric bypass surgery

Background: Nonalcoholic steatohepatitis (NASH) is a form of fatty liver disease that is increasingly recognized. There are limited data on the prevalence of NASH and the role of risk factors for NASH among the morbidly obese. Hypothesis: The prevalence of asymptomatic NASH among morbidly obese patients undergoing gastric bypass surgery is high, and there are identifiable risk factors for NASH. Design: Prospective case study. Setting: University hospital. Patients: Forty-eight consecutive patients undergoing gastric bypass surgery who had a concurrent open liver biopsy. Exclusion criteria included current consumption of more than 2 alcohol beverages monthly and known cirrhosis. A hepatopathologist blinded to clinical data reviewed biopsy specimens. Main Outcome Measures: The presence of NASH or severe fibrosis, preoperative body mass index (BMI) (calculated as weight in kilograms divided by the square of height in meters), fasting triglyceride level, and presence of type 2 diabetes mellitus (DM). Results: Patients (mean+/-SD age, 42+/-10 years; 33 women) had an initial mean BMI of 59.9+/-12. Thirty-one patients (65%) had moderate to severe steatosis. Only 6 (12%) had advanced fibrosis. Sixteen (33%) had evidence of NASH. There was no difference in mean age, sex, BMI, or fasting triglyceride level between patients with and without NASH or advanced fibrosis. The odds of NASH were 128 times greater (95% confidence interval [CI], 5.2-3137.0) and the odds of severe fibrosis 75 times greater (95% CI, 4.5-1247.0) in patients with DM than in those without DM. Preoperative BMI was not independently associated with NASH (odds ratio, 1.01; 95% CI, 0.9-1.1) or severe fibrosis (odds ratio, 0.9; 95% CI, 0.86-1.02) after adjustment for DM. Conclusions: Moderate to severe hepatic steatosis and NASH are common among individuals undergoing gastric bypass procedures. Diabetes mellitus but not BMI is associated with NASH and advanced hepatic fibrosis in these patients.