Chronic Hepatitis B affects about 9% of the adult population in Hong Kong. Nowadays, oral antiviral drugs are very effective in suppressing the replication of hepatitis B virus (HBV). However, most patients experience relapse of hepatitis after stopping the antiviral drug. As doctors have little guidance on the timing of stopping medication, most patients are put on life-long treatment. 


Hepatitis B surface antigen (HBsAg) is a unique protein produced by HBV. Researchers at the Center for Liver Health at CUHK monitored 53 chronic hepatitis B patients who were treated by lamivudine for an average of three years. The researchers found that seven of the nine patients who achieved HBsAg of ≤100 IU/ml at the end of lamivudine treatment did not have a relapse one year after stopping medication, while relapse occurred in 42 of the 44 patients with HBsAg levels >100 IU/ml at the end of treatment. 


In conclusion, an HBsAg level of ≤100 IU/ml is a good predictor for disease control after stopping antiviral therapy. Therefore, CUHK recommends regular monitoring of serum HBsAg in chronic hepatitis B patients on antiviral drugs to decide when to stop therapy.