Clinical significance of quantitative HBsAg titres and its correlation with HBV DNA levels in the natural history of hepatitis B virus infection

Abstract Background/objective Quantification of serum hepatitis B antigen (HBsAg) is an important test that marks active infection with hepatitis B and helps in the prediction of the clinical outcome and management of hepatitis B virus (HBV) infection. Correlation with HBV DNA quantitative levels may help in developing strategies for antiviral treatment. This study is aimed to evaluate HBsAg titres in various phase of HBV infection in HBsAg positive patients, and its correlation with HBV DNA viral load levels. Methods 976 HBV related patients were analyzed in this retrospective cross-sectional study. Patients were categorized based on the phase of HBV infection: immune tolerant phase (IT, n = 123), immune clearance phase (IC, n = 192), low-replicative phase (LR, n = 476), and HBeAg-negative hepatitis (ENH, n = 185). HBsAg titers were quantified and correlated with HBV-DNA levels and clinical parameters. Results Median HBsAg titres were different between each phases of HBV infection (p < 0.001): (4.62 log10 IU/ml), IC (3.88 log10 IU/ml), LR (2.76 log10 IU/ml) and ENH (2.94 log10 IU/ml). HBsAg and HBV DNA levels showed significant correlation in the whole group (r = 0.694, p < 0.001), and this was also observed in different phases of HBV infection. Strong correlation in IT phase (r = 0.603, p < 0.001) and IC phase (r = 0.523, p < 0.001), moderate in LR phase (r = 0.362, p < 0.001) and weak in ENH (r = 0.110, p = 0.04). No correlation was observed between serum HBsAg levels and biochemical parameters. Conclusion The study demonstrated significant difference in the median baseline values of serum HBsAg titres in different phases of HBV infection and provides additional information in understanding the natural history of HBV-infection.