Nonalcoholic fatty liver disease (NAFLD) encompasses nonalcoholic fatty liver (NAFL) and nonalcoholic steatohepatitis (NASH), which may progress to liver fibrosis, cirrhosis, and even hepatocellular carcinoma.NAFLD has recently become one of the most common causes of chronic liver injury in many countries, particularly Asia [1]. NASH has been defined as steatosis with inflammation, hepatocellular injury, and possible fibrosis [2]. It is necessary to distinguish NASH as early as possible. Patients with fibrosis ≥ 3 would be candidates for monitoring and treatment. The gold standard tool to diagnose NAFLD is liver biopsy. Histological scoring was performed according to the steatosis grade (S0, <5%;S1, 5% to 33%;S2, 33% to 66%; S3,more than 66%) and fibrosis (F0,absence of fibrosis;F1,perisinusoidal or portal fibrosis;F2, perisinusoidal and portal/periportal fibrosis; F3, septal or bridging fibrosis; F4,cirrhosis) [3]. However, disadvantages include the invasive nature, complications, and sampling variation.

FibroScan based on ultrasonication is a new technique that allows rapid and noninvasive measurement of steatosis and fibrosis simultaneously, and the median values are used to quantify liver fibrosis and steatosis [4]. FibroScan comprises two parameters, the controlled attenuation parameter (CAP) to estimate steatosis and liver stiffness measurement (LSM) to estimate fibrosis. FibroScan is equipped with two probes for adults: the M probe and XL probe. Liver stiffness measurement often fails in obese patients, but the success rate can be improved using the XL probe. The first is designed for the distance from the skin to the liver capsule (SCD) of general patients < 2.5 cm or a BMI < 30 kg/m². The second is designed for obese patients 2.5 cm ≤ distance from the skin to the liver capsule ≤ 3.5 cm or a BMI greater than 30 kg/m². However, the clinical use of FibroScan is limited because of uncertainty regarding optimal cut-offs and the influence of covariates [5], [6]. Some researchers are studying the cut-offs of steatosis and fibrosis using FibroScan, but the percentage of NAFLD is usually <50% [7]. We aimed to determine the diagnostic value of FibroScan in the stage of steatosis and fibrosis in NAFLD and the optimal CAP and LSM cut-offs for steatosis and fibrosis grades. Therefore, we conducted a meta-analysis. Larger studies are warranted to evaluate the relationship between steatosis and fibrosis and the value of FibroScan in the diagnosis of NASH, using the biopsy as a reference [8].