Outcome of adefovir add‐on lamivudine rescue therapy of up to 5 years in patients with lamivudine‐resistant chronic hepatitis B

Background and Aim: We investigated the long‐term efficacy of adefovir add‐on lamivudine rescue therapy in lamivudine‐resistant chronic hepatitis B and the optimal cutoff hepatitis B virus (HBV) DNA level that predicts complete virological response (CVR) among patients without CVR after 1 year of treatment. Methods: We reviewed 167 lamivudine‐resistant chronic hepatitis B patients who received adefovir add‐on rescue therapy for up to 5 years. Multivariate analysis, area under the receiver operating characteristic curves, and Youden index were used. Results: Median age was 47.0 years; 112 patients were male. Median baseline HBV DNA level was 6.6 log 10  IU/mL; hepatitis B e antigen was positive in 130 (77.4%) patients. Five‐year CVR, alanine aminotransferase normalization, hepatitis B e antigen seroconversion, and adefovir resistance rates were 86.9%, 92.5%, 16.7%, and 6.0%, respectively. One‐year HBV DNA level independently associated with CVR. Optimal cutoff HBV DNA level to predict CVR among patients who failed to achieve CVR at 1 year was 800 IU/mL (area under receiver operating characteristic curve 0.752; sensitivity 49.3%, specificity 93.5%). During the 5‐year treatment, 92.1% of patients with favorable response (HBV DNA < 800 IU/mL at 1 year) achieved CVR; 45.6% achieved CVR among suboptimal responders (HBV DNA ≥ 800 IU/mL at 1 year) ( P  < 0.001). Conclusion: Complete virological response or HBV DNA level < 800 IU/mL after 1 year adefovir add‐on lamivudine rescue therapy can favorably predict CVR.