Nonalcoholic fatty liver disease (NAFLD) has become the predominant cause of chronic liver injury worldwide, which refers to the presence of ≥ 5% hepatic steatosis (HS) without other competing etiologies, including chronic viral hepatitis, excessive alcohol consumption, use of steatogenic medication or hereditary disorders [1]. Its spectrum ranges from nonalcoholic fatty liver (NAFL), nonalcoholic steatohepatitis (NASH) to cirrhosis or even carcinoma, and is associated with the features of metabolic syndrome such as hypertension, insulin resistance, diabetes mellitus (DM) and dyslipidemia, increases risks of cardiovascular disease, and accelerates the progression of underlying disease, leading to severe consequences [2–4]. NALFD patients with DM is prone to develop NASH, liver fibrosis and cirrhosis, and even liver cancer. The overall prevalence of NAFLD among patients with type 2 diabetes mellitus (T2DM) is 55%, more than 2-fold higher than in the general population, with a very high rate of NASH [5–7]. In the course of NAFLD, liver fibrosis, an important predictor of adverse prognosis, is the most relevant target for early diagnosis and treatment, as it has been associated with further deterioration of cirrhosis and increased overall mortality [8, 9]. In our recent study, fibrosis occurred in up to 50% of patients with both NAFLD and T2DM [10]. Considering the huge number of patients with T2DM, the burden of the management of NAFLD seems to be enormous. Although the effective therapies for NAFLD has not been established, early intervention can significantly improve the poor prognosis of NAFLD. Therefore, the accurate and early detection of NAFLD in patients with abnormal glucose metabolism, especially the staging of liver fibrosis, is crucial [8, 11, 12].
Liver biopsy, an invasive procedure, has been recommended as the gold standard for diagnosis and classification of NAFLD, but the limitations of possible bleeding risks and sampling errors make it unsuitable for screening and frequent monitoring [13–15]. Therefore, non-invasive alternatives to liver biopsy have been investigated, such as serum biomarkers, clinical scoring systems and imaging tests including ultrasonography, FibroScan, magnetic resonance elastography (MRE), proton magnetic resonance spectroscopy (1H-MRS) and magnetic resonance imaging-derived proton density fat fraction (MRI-PDFF) etc. [16, 17] Among them, FibroScan (EchoSens, Paris, France) is recommended by the 2018 NAFLD guidance because of its convenience, clinically accessibility, low cost and simultaneous measurement of fibrosis and steatosis16. Liver stiffness measurement (LSM) obtained using FibroScan is one parameter for the diagnosis and quantification of liver fibrosis by measuring mechanical or ultrasound shear wave propagation through the hepatic parenchyma [18, 19].
There exist several studies assessing diagnostic performance of FibroScan, most of which targeted at patients with chronic hepatitis B [20, 21], while others focused on NAFLD [18, 22, 23]. Transient elastography expert consensus pointed out that there are differences in the cut-off values in patients with liver fibrosis caused by various etiologies, consists of Hepatitis B, Hepatitis C and NAFLD etc. Factors such as liver inflammation activity manifested by alanine aminotransferase (ALT) or increased bilirubin levels, excessive alcohol intake and eating may lead to increase of LSM values [24]. In view of the promoting effect of abnormal glucose metabolism on liver disease, NAFLD patients with abnormal glucose metabolism may have specific cut-off values differentiated from general NAFLD patients. However, up to now, there are no studies focusing on these population and lack of cut-off values for them.
The aim of this study was to evaluate the diagnostic performance of FibroScan and obtain cut-off values in NAFLD patients with abnormal glucose metabolism, and investigate whether metabolic indicators would affect the measurement of FibroScan, in order to provide a clinical advice for the application of FibroScan in the diagnosis and evaluation of NAFLD patients.