Prevalence of nonalcoholic steatohepatitis in Japanese patients with morbid obesity undergoing bariatric surgery.

BACKGROUND: Patients with morbid obesity selected for bariatric surgery have a high prevalence of nonalcoholic steatohepatitis (NASH); however, the incidence is varied and depends on race. The prevalence of NASH in obese Japanese patients is unknown. We evaluated the prevalence of NASH in a prospective cohort of Japanese patients with morbid obesity.

METHODS: From October 2009 to July 2011, consecutive patients requiring bariatric surgery underwent a liver biopsy during the operation. The indications for bariatric surgery followed the guidelines of the Asia-Pacific Metabolic and Bariatric Surgery Society.

RESULTS: One hundred two patients (55 males and 47 females, age 42.7 ± 10.7 years) were analyzed. The mean body mass index was 42.1 ± 8.2 kg/m(2). Among the 102 patients, 84 patients (82.4%) had nonalcoholic fatty liver disease and 79 patients (77.5%) had NASH. The grading and staging of NASH by Brunt's classification were as follows: grade 0 steatosis, one patient; grade 1 steatosis, 35 patients; grade 2 steatosis, 32 patients; grade 3 steatosis, 11 patients; stage 1 fibrosis, 25 patients; stage 2 fibrosis, 38 patients; stage 3 fibrosis, 16 patients, stage 4 fibrosis, no patients. The body weight, waist-hip ratio, visceral fat area, and aspartate aminotransferase, alanine aminotransferase, γ-glutamyl transpeptidase, fasting plasma glucose, fasting plasma insulin, C peptide, hemoglobin A1c, and homeostasis model assessment insulin resistance levels were significantly elevated in the NASH group in comparison with the non-NASH group. The platelet count was significantly decreased in the NASH group. The waist-hip ratio and the alanine aminotransferase, fasting plasma glucose, and homeostasis model assessment insulin resistance levels were found to be independent predictors of NASH in a multivariate analysis.

CONCLUSION: The prevalence of NASH was 77.5% in this prospective Japanese cohort. The prevalence of NASH in Japanese morbidly obese patients was extremely high, and early intervention should be undertaken.