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

Abstract

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. 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 <9IU/mL. Viral responses at 6months were classified as PCR negativity, partial virologic response (PVR, HBV DNA <2000 IU/mL), or inadequate virologic response (IVR, HBV DNA≥2000IU/mL). 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 6months showed significant differences among the three groups (P<0.0001 and P= 0.0005, respectively). Pre-treatment HBV DNA level and viral response at 6months is associated with treatment outcome for adefovir-add on therapy in lamivudine resistance.