Chasing after novel non-invasive markers to identify advanced fibrosis in NAFLD

Non-alcoholic fatty liver disease (NAFLD) is an increasingly recognized cause of liver disease worldwide. It is estimated that approximately 20-30% of the population are affected by NAFLD in the world, including Korea. The NAFLD spectrum ranges from relatively benign simple steatosis to non-alcoholic steatohepatitis (NASH), which can progress to liver cirrhosis and its complications such as liver failure and hepatocellular carcinoma. Patients with NASH-associated liver cirrhosis are considered to have a poor prognosis. Therefore, it is important to screen subjects with advanced fibrosis. Currently, liver biopsy remains the gold standard for identifying the presence of steatohepatitis and liver fibrosis in patients with NAFLD. However, it is generally acknowledged that liver biopsy is limited by its invasiveness, cost, and potential procedure-related complications. Accordingly, there has been significant clinical interest in developing non-invasive tools for the detection of advanced fibrosis among patients with NAFLD. Recently, transient elastography, which measures liver stiffness non-invasively, has been proposed for identifying advanced fibrosis in NAFLD. Along with the assessment of the degree of liver fibrosis, a novel technology based on the properties of ultrasonic signals of transient elastography, referred to as the controlled attenuation parameter (CAP), has been proposed for the measurement of hepatic fat content. Although the recent studies support the use of CAP as a non-invasive method for assessing the degree of hepatic steatosis, its use for identifying advanced fibrosis in NAFLD remains to be explored. Several clinical scoring systems have been developed for distinguishing advanced fibrosis in patients with NAFLD. Some of these scoring systems include the NAFLD fibrosis score, the BARD score, and the FIB-4 score. The major advantage of using these scoring systems is that they are readily available from clinical and laboratory indices. Several biomarkers also have been investigated for the diagnosis of advanced fibrosis in NAFLD. Since the constituents of extracellular matrix (ECM) are expected to be released into circulation in advanced liver fibrosis, the ECM components have been studied for their association with liver fibrosis. These biomarkers include serum hyaluronic acid, type IV collagen 7S domain, tissue inhibitor of metalloproteinase 1 (TIMP1), and procollagen III (PIIINP). However, studies on these scoring systems and biomarkers showed conflicting results and thus further validation is required prior to their widespread use. The red blood cell distribution width (RDW), an automated Chasing after novel non-invasive markers to identify advanced fibrosis in NAFLD