Background & aims: The non-invasive identification of steatohepatitis (NASH) in patients with Non-Alcoholic Fatty Liver Disease is an unmet need in clinical practice. Index of NASH (ION) is a new tool for the prediction of NASH. We aimed to externally validate ION and to compare it with CK-18. Since necroinflammation precedes fibrosis, we also tested ION in combination with non-invasive tools for fibrosis.
Methods: We analysed data from 292 Italian patients (169 Southern cohort, and 123 Northern cohort) with an histological diagnosis of NAFLD. The ION, FIB-4 and NFS scores were calculated according to published algorithms. Serum cytokeratin18-Aspartate396 levels and liver stiffness (LS) by Fibroscan were assessed within three months from liver biopsy.
Results: The diagnostic accuracy of ION for the identification of NASH was not as satisfactory as reported (area under the ROC curve, AUROC = 0.687 [95% CI = 0.62-0.75]). The proposed cut-off value ≥50 showed a poor sensitivity (Se) (28%) and a good specificity (Sp) (92%), with a positive predictive value (PPV) of 91% and a negative predictive value (NPV) of 30%. A new cut-off value >26 improved Se (73%) but decreased Sp (60%) (PPV of 84% and a NPV of 43%). ION performed slightly better in obese NAFLD (AUROC = 0.700). The combination of ION and markers of fibrosis did not improve the identification of advanced liver disease.
Conclusions: ION is not feasible for the non-invasive diagnosis of NASH across different populations of NAFLD patients, mainly because its limited reproducibility in non-obese subjects.
Keywords: fibrosis; non-invasive marker; steatohepatitis.
© 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.