The NAFLD fibrosis score: a noninvasive system that identifies liver fibrosis in patients with NAFLD

Patients with nonalcoholic fatty liver disease (NAFLD) and advanced liver fibrosis are at the highest risk for progressing to end-stage liver disease. We aimed at constructing and validating a scoring system consisting of routinely measured and readily available clinical and laboratory data to separate NAFLD patients with and without advanced fibrosis. A total of 733 patients with liver biopsy confirmed NAFLD were divided into two groups to construct (n=480) and validate (n=253) a scoring system. Routine demographic, clinical, and laboratory variables were analyzed by multivariate modeling to predict presence/absence of advanced fibrosis. Age, hyperglycemia, body mass index, platelet count, albumin and AST/ALT ratio were independent indicators of advanced liver fibrosis. A scoring system with these six variables had an area under the receiver operating characteristic curve of 0.88 and 0.82 in the estimation and validation groups, respectively. Applying the low cutoff score (-1.455), advanced fibrosis could be excluded with high accuracy (negative predictive value of 93% and 88% in the estimation and validation groups, respectively). Applying the high cutoff score (0.676), the presence of advanced fibrosis could be diagnosed with high accuracy (positive predictive value of 90% and 82% in the estimation and validation group, respectively). By applying this model, a liver biopsy would have been avoided in 549 (75%) of the 733 patients, with correct prediction in 496 (90%). In conclusion: a simple scoring system accurately separates NAFLD patients with and without advanced fibrosis, rendering liver biopsy for identification of advanced fibrosis unnecessary in a substantial proportion of patients.