Development and validation of a novel non-invasive test for diagnosing fibrotic non-alcoholic steatohepatitis in patients with biopsy-proven non-alcoholic fatty liver disease

Background and Aim There is an immediate need for non-invasive accurate tests for diagnosing liver fibrosis in patients with non-alcoholic steatohepatitis (NASH). Previously, it has been suggested that MACK-3 (a formula that combines homeostasis model assessment-insulin resistance with serum serum aspartate aminotransferase and cytokeratin [CK]18-M30 levels) accurately identifies patients with fibrotic NASH. Our aim was to assess the performance of MACK-3 and develop a novel, non-invasive algorithm for diagnosing fibrotic NASH. Methods Six hundred and thirty-six adults with biopsy-proven non-alcoholic fatty liver disease (NAFLD) from two independent Asian cohorts were enrolled in our study. Liver stiffness measurement (LSM) was assessed by vibration-controlled transient elastography (Fibroscan). Fibrotic NASH was defined as NASH with a NAFLD activity score (NAS) >= 4 and F >= 2 fibrosis. Results Metabolic syndrome (MetS), platelet count and MACK-3 were independent predictors of fibrotic NASH. On the basis of their regression coefficients, we developed a novel nomogram showing a good discriminatory ability (area under receiver operating characteristic curve [AUROC]: 0.79, 95% confidence interval [CI 0.75-0.83]) and a high negative predictive value (NPV: 94.7%) to rule out fibrotic NASH. In the validation set, this nomogram had a higher AUROC (0.81, 95%CI 0.74-0.87) than that of MACK-3 (AUROC: 0.75, 95%CI 0.68-0.82; P < 0.05) with a NPV of 93.2%. The sequential combination of this nomogram with LSM data avoided the need for liver biopsy in 56.9% of patients. Conclusions Our novel nomogram (combining MACK-3, platelet count and MetS) shows promising utility for diagnosing fibrotic NASH. The sequential combination of this nomogram and vibration-controlled transient elastography limits indeterminate results and reduces the number of unnecessary liver biopsies.