Abstract: Objective To investigate the dynamic changes of quantitative hepatitis B surface antigen concentration in predicting virologic response to entecavir（ETV） therapy in patients with HBeAg-positive chronic hepatitis B（CHB）. Methods Seventy-eight treatment-naive patients with HBeAg-positive CHB receiving ETV （0.5 mg/daily） were recruited and followed up for 1 year from January 2011 to January 2012. Serum samples were collected at baseline and every 3 months after ETV treatment. Serum HBsAg and HBeAg concentrations were quantitatively determined by chemiluminescence assay and serum HBV DNA levels were determined by real-time polymerase chain reaction. The correlation of HBsAg and HBV DNA level was analyzed by Pearson correlation analysis. The receiver operating characteristic curve（ROC） was used to predicted HBV virologic response and determine the optimal threshold. Results Sixty-nine（88.5%）patients achieved virologic response（VR）,while 9 did not;there was no significant difference for baseline levels of serum ALT in patients with VR [（141.8±27.2）IU/ml] and without [（136.2±29.7） IU/ml,t=0.27,P=0.793];serum HBV DNA levels in patients with VR[（6.7±1.0）lg IU/ml] was significantly lower than that in patients without[（7.6±0.8）lg IU/ml,t=-2.27,P=0.033];there was no significant difference in HBsAg concentration between patients with VR and without[（3.8±0.6） lg IU/ml vs.（4.0±0.4）lg IU/ml,t=-1.75,P=0.094]. HBsAg and HBV DNA levels were positively correlated（r=0.45,P=0.02）. there was a rapid decline in HBsAg concentration during the first 3 months of therapy,followed by a much slower decline in the subsequent periods;from the baseline to month 3,the reduction of HBsAg concentration in patients with VR was faster than in patients without[（0.3±0.2） lg IU/ml vs.（0.2±0.1） lg IU/ml,t=2.245,P=0.035]. The lg HBsAg concentration at month 3 showed the biggest area under the curve （AUC）（AUC=0.840,P=0.005）,and the max Youden index（0.602） was appeared at the cut-off value of 3.85 lg IU/ml,with a diagnostic sensitivity and specificity of 84.2% and 78.7%,respectively. Conclusions lg HBsAg≤3.85 lg IU/ml after 3 months of ETV treatment can be used as an indicator to predict the virologic response of patients with CHB 1-year after ETV treatment.

Key words: Chronic hepatitis B, Hepatitis B surface antigen, Hepatitis B e antigen, Entecavir, Treatment