HBV DNA level at 24 weeks is the best predictor of virological response to adefovir add-on therapy in patients with lamivudine resistance

Background: The aim of this study was to investigate the relationship between HBV DNA levels at baseline and on-treatment and the virological response at 96 weeks after adefovir add-on therapy in chronic hepatitis B (CHB) patients with lamivudine resistance. Methods: Lamivudine and adefovir combination therapy was administered to 122 CHB patients for >24 months. Results: Virological response (HBV DNA negativity) was achieved in 53 (43.3%) and 62 patients (50.8%) at 48 and 96 weeks, respectively. The receiver operating characteristic curve analysis showed that the HBV DNA level at week 24 had a greater power (area under the receiver operating characteristic curve 0.978; 95% CI 0.949, 1.000; P<0.001) to predict the virological response at week 96 of treatment than did the pre-treatment HBV DNA level (area under the receiver operating characteristic curve 0.771; 95% CI 0.640, 0.902; P<0.001). The best cutoff value for the HBV DNA level, at week 24, for the prediction of the virological response at week 96 was 200 IU/ml (3 log(10) copies/ml), with a sensitivity and specificity of 90.3% and 95.0%, respectively. Using this time frame and cutoff value, 56 (90.3%) out of 62 patients that had a virological response at 96 weeks had <200 IU/ml HBV DNA at 24 weeks. Conclusions: Although the HBV DNA level at baseline is often used to predict the antiviral potency of lamivudine and adefovir combination treatment in CHB patients with lamivudine resistance, the results of this study suggest that the HBV DNA level at 24 weeks is a better marker for the virological response.