April 2018 Volume 16, Issue 4, Pages 491–494
Hepatic Steatosis and its Effects on Fibrosis in Patients With Chronic Hepatitis B Virus Infection
Mauricio Garcia-Saenz-de-Sicilia, MD, Andres Duarte-Rojo, MD, MS, DSC
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Obesity rising prevalence has reawakened interest in the potential interactions between chronic viral hepatitis and hepatic steatosis. The metabolic syndrome and its components are independent risk factors associated with fibrosis progression, development of cirrhosis,1 and potentially with lack of fibrosis reversal following antiviral therapy in chronic viral hepatitis.2 However, the particular role of hepatic steatosis, the hallmark of nonalcoholic fatty liver (NAFLD), has been less of a focus of attention in chronic hepatitis B virus (HBV) infection when compared with chronic hepatitis C, in part because of the lack of proper evaluation tools.3
Liver biopsy is considered to be the gold standard for steatosis grading. However, it is invasive, has potential life-threatening complications, can result in sampling errors particularly when fatty infiltration is unevenly distributed (typical biopsy represents 1/50,000 of liver), and interpretation reaches only moderate interobserver or intraobserver agreement.4 Furthermore, repeated monitoring following a therapeutic intervention is hard to justify because of the invasive nature of the procedure and cost, and the fact that noninvasive options are now available. Imaging techniques provide reliable noninvasive alternatives to assess steatosis. Proton density fat fraction from magnetic resonance is perhaps the most accurate method for steatosis quantification; however, it is not a point-of-care method, and has associated high costs and limited availability, making it impractical for routine clinical care at most institutions. All of these limitations are at least partially overcome by the controlled attenuated parameter (CAP) feature from FibroScan (Echosens, Paris, France). This technique, based on the principle that fat affects ultrasound propagation, quantifies variations in M-mode (unidimensional) ultrasound attenuation during liver stiffness measurement (LSM) with vibration-controlled transient elastography, to yield a steatosis estimate. When testing CAP against steatosis grading by liver biopsy, fair to excellent performance has been reported across studies, and discrepancies are likely explained by variations in liver disease etiology, population body composition, and spectrum bias (Table 1). Although CAP interpretation has been limited by uncertainty as to the optimal cutoff values between grades of steatosis, Karlas et al5 have recently brought some certainty to this issue. In a meta-analysis including 2735 cases with histology and CAP analysis, the authors defined cutoff values and variables influencing the output, such as body mass index (BMI), diabetes, and etiology.
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