Risk factors and prevalence of liver disease in review of 2557 routine liver biopsies performed during bariatric surgery

Background: Obesity is a known risk factor for nonalcoholic fatty liver disease (NAFLD). However, among individuals undergoing bariatric surgery, the prevalence and risk factors for NAFLD, as well as distinct phenotypes of steatosis, nonalcoholic steatohepatitis (NASH), and fibrosis remain incompletely understood. Objectives: To determine the prevalence and risk factors for steatosis, NASH, and fibrosis in individuals undergoing routine bariatric surgery. Setting: Academic medical center in the United States. Methods: Liver wedge biopsies were performed at the time of surgery between 2001 and 2017. Pathology reports were reviewed, and individuals were grouped by NAFLD phenotype. Covariates including demographic characteristics, co-morbidities, and preoperative laboratory values were compared between groups using Student's t test, Pearson's χ², and logistic regression. Results: Liver biopsies were obtained in 97.7% of first-time bariatric procedures, representing 2557 patients. Mean age was 45.6 years, mean body mass index was 46.7, and most were non-Hispanic white (76.1%) and female (71.6%). On histologic review 61.2% had steatosis and 30.9% NASH. Fibrosis was identified in 29.3% of individuals, and 7.8% had stage ≥2 fibrosis. On logistic regression, elevated aspartate aminotransferase (odds ratio [OR] 1.87; P < .001) and elevated alanine aminotransferase (OR 1.62; P < .001) were independently associated with fibrosis. Elevated hemoglobin A1C of 5.7% to 6.5% (OR 1.29; P < .01) and >6.5% (OR 3.23; P < .001) were also associated with fibrosis. A similar trend was seen for NASH. Conclusions: NASH and/or fibrosis is present in nearly one third of patients undergoing routine bariatric surgery. Risk factors include diabetes, elevated liver enzymes, and diabetes. Risk assessment and aggressive screening should be considered in patients undergoing bariatric surgery.