Viral response at 6 months is associated with treatment outcome of adefovir add-on therapy for lamivudine-resistance


  • Author contributions: All the authors cooperated to make this manuscript and they all had the original idea for the study. We equally shared the responsibility for data collection, data handling, statistical analyses, writing, and reviewing the manuscript.

Professor Seung Woon Paik, 50 Irwon-dong, Gangnam-gu, Seoul 135-710, Korea. E-mail:


Background and Aim:  Adefovir add-on therapy is recommended for patients infected with lamivudine-resistant hepatitis B virus (HBV). We aimed to describe the long-term treatment outcome and predictors for good response of adefovir add-on therapy.

Methods:  A total of 559 chronic hepatitis B (CHB) patients who had been treated for at least 12 months with adefovir add-on therapy due to resistance to lamivudine were retrospectively included. Complete virologic response (CVR) was defined as serum HBV DNA < 9 IU/mL. Viral responses at 6 months were classified as PCR negativity, partial virologic response (PVR, HBV DNA < 2000 IU/mL), or inadequate virologic response (IVR, HBV DNA ≥ 2000 IU/mL).

Results:  The median duration of follow-up was 31.5 months (range, 12–56). The cumulative probabilities of CVR during adefovir add-on therapy were 58%, 70%, 78%, and 80% at 12, 24, 36, and 43 months, respectively. The cumulative rates of resistance to adefovir were 0.4%, 0.8%, and 3.1% at 12, 24, and 36 months, respectively. The only baseline factor associated with CVR (hazard ratio 0.83, 95% confidence interval 0.62–0.91, P ≤ 0.001) and resistance to adefovir (hazard ratio 1.925, 95% confidence interval 1.13–3.30, P = 0.017) was serum HBV DNA level. Comparison of the cumulative rates of CVR and resistance to adefovir according to viral response at 6 months showed significant differences among the three groups (P < 0.0001 and P = 0.0005, respectively).

Conclusions:  Pre-treatment HBV DNA level and viral response at 6 months is associated with treatment outcome for adefovir-add on therapy in lamivudine resistance.