O116 HEPATITIS B SURFACE ANTIGEN (HBsAg) LEVELS DIFFER ACROSS HBV GENOTYPE AND PHENOTYPE: RESULTS FROM THE ADULT COHORT STUDY OF THE NIDDK-SPONSORED HEPATITIS B RESEARCH NETWORK

Abstract

O116 HEPATITIS B SURFACE ANTIGEN (HBsAg) LEVELS DIFFER ACROSS HBV GENOTYPE AND PHENOTYPE: RESULTS FROM THE ADULT COHORT STUDY OF THE NIDDK-SPONSORED HEPATITIS B RESEARCH NETWORK W.P. Brouwer, Y.K. Cloonan, J.J. Feld, R.P. Perrillo, M.W. Fried, D.K. Wong, H.L.A. Janssen, for the NIDDK-Sponsored Hepatitis B Research Network (HBRN). Center for Liver Disease, Toronto Western Hospital, University Health Network, Toronto, ON, Canada; Data Coordination Centre, University of Pittsburgh, Pittsburgh, KS, United States; Center for Liver Disease, Toronto Western and General Hospital, University Health Network, Toronto, ON, Canada; Hepatology, Baylor University Medical Center, Dallas, TX, UNC Liver Center, University of North Carolina, Chapel Hill, NC, United States E-mail: w.p.brouwer@erasmusmc.nl Background and Aims: HBsAg-levels reflect the interaction between the immune system and the hepatitis B virus (HBV) and are used as a predictor of response to interferon. However, large studies investigating all major HBV-genotypes and their impact on HBsAg-levels during the course of HBV-infection are lacking. Methods: At 22 US/Canadian centres, 1745 HBV-infected adults were enrolled. Analyses included non-treated participants with chronic HBV mono-infection, with available data on HBsAg-levels, ALT, HBVDNA-levels and HBV-genotype. Disease phenotypes were defined using HBeAg-status, ALT and HBVDNA-levels. Overall and within HBV-genotype, median HBsAg-levels were compared across phenotype using Kruskal–Wallis tests. Results: In total, 741 participants were analyzed. Median age was 42 years, 51% were male and 75% were Asian. Fifty-three (7%) were immune tolerant (IT), 101 (14%) HBeAg(+) active (IA+), 120 (16%) HBeAg(−) active (IA−), 202 (27%) inactive carriers (IC) and 265 (36%) indeterminate (ID). The most common HBVgenotypes were A (17%), B (37%), C (34%) and D (8%). HBsAglevels differed across phenotypes (p < 0.01), with highest levels observed in IT (median =4.8 log10 IU/ml; IQR=4.4–4.9), and lowest in IC (median =3.1 log10 IU/ml; IQR=2.1–3.7). Also, median HBsAglevels (log10IU/mL) differed across HBV-genotypes and were 4.0 (A), 3.0 (B), 3.5 (C) and 3.3 (D) (p < 0.01). Within HBV-genotype, HBsAglevels differed across phenotype (p < 0.01 for HBV-genotype A–C, and p=0.04 for genotype D; figure). Interestingly, mean HBsAglevels for IC infected with HBV-genotype A were comparable to HBsAg-levels of IA+ in the other HBV-genotypes investigated.