310 Obesity Surgery, 15, 2005 © FD-Communications Inc. Obesity Surgery, 15, 310-315 Background: Nonalcoholic fatty liver disease (NAFLD) is a common form of chronic liver disease in the United States. It is commonly associated with the components of the metabolic syndrome including obesity. From the spectrum of NAFLD, only patients with nonalcoholic steatohepatitis (NASH) have been convincingly shown to have a potential for progres- sion to cirrhosis. We report the prevalence of NAFLD and NASH as well as predictors of NASH and advanced fibrosis in morbidly obese patients. Methods: 212 consecutive patients who underwent bariatric surgery were enrolled in the study. A liver biopsy was performed at the time of the surgery. Causes of chronic liver disease other than NAFLD were excluded by clinical and laboratory evaluation. Results: The prevalence of NAFLD was 93%. Of those with NAFLD, 26% had NASH. 17 patients (9%) had advanced fibrosis (i.e., bridging fibrosis or cir- rhosis). Male gender, AST, and type 2 diabetes melli- tus were independently associated with NASH. Waist- to-hip ratio, AST, and focal hepatocyte necrosis on liver biopsy were independently associated with advanced fibrosis. Interestingly, while AST was asso- ciated with NASH and advanced fibrosis, the majority of the patients with either NASH or advanced fibrosis had normal AST. Conclusions: NAFLD and NASH are very common in morbidly obese patients undergoing bariatric sur- gery. Features associated with the metabolic syn- drome and liver cell injury are independently associ- ated with either NASH or advanced fibrosis. Key words: Morbid obesity, steatohepatitis, cirrhosis, bariatric surgery, NAFLD Introduction Nonalcoholic fatty liver disease (NAFLD) is believed to be the most common form of chronic liver disease in the United States. 1,2 The spectrum of histologic findings in NAFLD ranges from simple steatosis and steatosis with nonspecific inflammation to nonalco- holic steatohepatitis (NASH) to cirrhosis. 3,4 NASH can progress to end-stage liver disease and its com- plications, including hepatocellular carcinoma. 5 Several studies have implicated NASH as the under- lying pathology in cryptogenic cirrhosis and as such, NASH may also be an important indication for liver transplantation. 6,7 Furthermore, NASH has been shown to recur after liver transplantation. 8 NAFLD is commonly associated with obesity, hyperlipidemia, and type 2 diabetes mellitus (DM), conditions associated with the metabolic syn- drome. 9,10 Some of the earliest descriptions of NAFLD were in obese patients. 11,12 Subsequent reports have observed obesity in 30-100% of patients with NAFLD. Additionally, in patients with morbid obesity undergoing bariatric surgery, the prevalence of NAFLD ranges from 74-98%, while that of NASH can be as high as 37%. 13-17 The asso- Predictors of Nonalcoholic Steatohepatitis and Advanced Fibrosis in Morbidly Obese Patients Janus P. Ong MD, MPH 1 ; Hazem Elariny, MD, PhD 1 ; Rochelle Collantes, MD, MPH 1 ; Abraham Younoszai, BS 1 ; Vikas Chandhoke, PhD 2 ; H. David Reines, MD 1 ; Zachary Goodman, MD, PhD 3 ; Zobair M. Younossi, MD, MPH 1,2 1 Center for Liver Diseases, Inova Fairfax Hospital; 2 Center for the Study of Genomics in Liver Diseases, Molecular and Microbiology Department, George Mason University; and 3 Armed Forces Institute of Pathology, Washington, DC, USA Reprint requests to: Zobair M. Younossi, MD, MPH, Center for Liver Diseases, Inova Fairfax Hospital, 3300 Gallows Rd, Falls Church, VA 22042, USA. Fax: (703) 698-3482 or (703) 208-6655; e-mail: zobair.younossi@inova.com