Noninvasive biochemical markers and surrogate scores in evaluating nonalcoholic steatohepatitis

The histological features of nonalcoholic steatohepatitis (NASH) are the presence of hepatic steatosis with concomitant inflammation, ballooned hepatocytes, and potential fibrosis, which can lead to liver cirrhosis. To reduce the need for liver biopsy, that is still the gold standard for diagnosing NASH, various noninvasive biomarkers have been investigated. This narrative review summarizes the current knowledge about noninvasive diagnostic biomarkers and scores proposed for patients with NASH. A search was performed in the main medical literature databases. The following search terms were used: NASH, noninvasive biomarkers or NASH scores and panels. We focused only on studies assessing NASH diagnosis or predictive values for biomarkers, panels and scores. Data on their accuracy in predicting NASH were collected. Several panels such as NAFLD Fibrosis Score (NFS), Fibrosis-4 (FIB-4), and FibroMeter presented good predictive values of NASH, with novel proteomics panels such as the NAFLD Fibrosis Protein Panel (NFPP) using mainly the adisintegrin and metalloproteinase with thrombospondin motifs like 2 (ADAMTSL2) that showed an advantage in predicting NASH compared to NFS and FIB-4. Another novel panel, Index of NASH (ION) performed better than cytokeratin 18 (CK-18) in excluding severe fibrosis, but the overall accuracy of ION and CK-18 was modest compared to NFS and FIB-4 as it did not provide any significant advantage. Noninvasive biomarkers are currently unable to replace liver biopsy and histological assessment. However, they may play a key and vital role in triaging patients for liver biopsy, lowering the related financial burden. Future studies are needed to verify the predictive values of the newly emerging tests and panels as well as to find more affordable and reliable noninvasive early diagnostic tools.