BACKGROUND/AIMS To optimize management of nonalcoholic fatty liver disease (NAFLD), a simple screening tool is necessary. In this study, we aimed to devise a simple index of NAFLD.

STUDY A cross-sectional study with 10,724 health check-up subjects (5362 cases with NAFLD versus age- and sex-matched controls) was conducted. Study subjects were randomly assigned to a derivation cohort or a validation cohort.

RESULTS Multivariate analysis indicated that high serum alanine aminotransferase (ALT) to serum aspartate aminotransferase (AST) ratio, high body mass index (BMI), and diabetes mellitus were independent risk factors of NAFLD (all P<0.001). Using these variables, a formula was derived by a logistic regression model: hepatic steatosis index (HSI)= 8 x(ALT/AST ratio)+BMI (+2, if female; +2, if diabetes mellitus). HSI had an area under receiver-operating curve of 0.812 (95% confidence interval, 0.801-0.824). At values of <30.0 or >36.0, HSI ruled out NAFLD with a sensitivity of 93.1%, or detected NAFLD with a specificity of 92.4%, respectively. Of 2692 subjects with HSI <30.0 or >36.0 in the derivation cohort, 2305 (85.6%) were correctly classified. HSI was validated in the subsequent validation cohort.

CONCLUSION HSI is a simple, efficient screening tool for NAFLD that may be utilized for selecting individuals for liver ultrasonography and for determining the need for lifestyle modifications.