Predictive value of HBsAg quantification for determining the clinical course of genotype C HBeAg-negative carriers

Background/Aims: Hepatitis B virus surface antigen (HBsAg) quantification has been suggested to discriminate inactive carriers from hepatitis e antigen (HBeAg) negative chronic hepatitis, but it could be genotype-dependent. We studied the predictive value of HBsAg quantification in genotype C HBeAg-negative hepatitis B virus (HBV) carriers. Methods: We recruited 104 HBeAg-negative HBV carriers with HBV DNA levels < 2,000 IU/ml and normal alanine aminotransferase (ALT) levels for at least 12 months and prospectively followed them for > 36 months. Patients were classified into two groups: inactive carriers (IC) who showed HBV DNA levels < 2,000 IU/ml and persistently ALT ≤ 40 IU/ml throughout the follow-up period and patients with HBeAg-negative chronic hepatitis (ENH). Results: After follow-up, 73 patients were categorized into the IC group and 31 patients into the ENH group. HBsAg levels were significantly lower in the IC group than in the ENH group. The diagnostic accuracy of single-point HBsAg levels for predicting viral activation was favourable (AUROC = 0.710, P < 0.001). Diagnostic accuracy improved when HBsAg was combined with baseline HBV DNA levels (AUROC = 0.750, P < 0.001). The combination of HBsAg levels > 850 IU/ml and HBV DNA > 850 IU/ml predicted the reactivation of HBV replication with 84.6% diagnostic accuracy. Conclusions: Although it is inferior to other genotypes and to serum HBV DNA alone, single-point HBsAg level has a favourable diagnostic accuracy in genotype C HBeAg-negative HBV carriers and is expected to provide additional information for managing chronic hepatitis B.