NAFLD INDEX: A SIMPLE SCREENING TOOL REFLECTING NONALCOHOLIC FATTY LIVER DISEASE IN THE KOREAN POPULATION

Abstract

Background and 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 that reflects the presence of NAFLD in the Korean population. Methods: A cross-sectional study was conducted on 10,724 health checkup subjects at a healthcare center (5,362 cases with NAFLD versus ageand sex-matched controls). Study subjects were randomly assigned to a derivation cohort or a validation cohort. An index reflecting the presence of NAFLD was derived in the derivation cohort and validated in the validation cohort. Results: Multivariable analysis indicated that body-mass index (BMI), serum alanine aminotransferase (ALT) to serum aspartate aminotransferase (AST) ratio, sex, and the presence of diabetes mellitus were independent predictors of NAFLD. Using these variables, a formula was derived using a linear regression model: NAFLD index (NAFLDI) = 8×ALT/AST ratio + BMI (+3, if female; +2, if diabetes mellitus). NAFLDI had an area under receiver-operating characteristics curve of 0.812 (95% confidence interval, 0.801−0.824). At a value of <31.0, NAFLDI ruled out NAFLD with a sensitivity of 89.0% and a negative likelihood ratio of 0.22, and at a value of >36.0, NAFLDI detected NAFLD with a specificity of 91.2% and a positive likelihood ratio of 5.42. In the validation cohort, the predictive power of NAFLDI was maintained at similar levels. NAFLDI had significant correlation with sonographic fatty liver grade (adjusted r2 = 0.334, P<0.001) (Figure 1). Conclusion: NAFLDI was a simple, efficient screening tool for NAFLD that could be utilized for selecting individuals for liver ultrasonography and for determining the need for lifestyle modifications.