HBsAg quantification for identification of liver disease in chronic hepatitis B virus carriers

Background & Aims: Quantification of hepatitis B surface antigen (HBsAg) has been proposed as a useful diagnostic marker for clinical staging (identification of inactive carrier state) and prognosis of chronic hepatitis B virus (HBV) infection. The aim of this study was to investigate the correlation between HBsAg levels in serum and histological liver damage in patients with chronic infection. Methods: HBsAg levels in serum (by Abbott Architect) were related to HBV DNA, ALT and histological score (n = 160) and covalently closed circular DNA (cccDNA) (n = 84). Results: HBsAg levels correlated with cccDNA, serum HBV DNA, ALT and high inflammation scores (P < 0.001). Among HBeAg-negative patients, an HBsAg level below 3.0 log(10) IU/ml identified minimal liver damage (normal ALT and mild inflammation) with a predictive value of 92% (alone) or 96% (in combination with HBV DNA <4.0 log(10) copies/ml), whereas an HBsAg level above 3.5 log(10) IU/ml identified severe inflammation with a predictive value of 16% (alone) or 33% (in combination with HBV DNA >5.0 log(10) copies/ml). Conclusions: HBsAg levels reflect clinical stage and liver disease, and a combined quantification of HBsAg and HBV DNA may improve clinical staging.