A Low Viral Load Predicts a Higher Initial Virologic Response to Adefovir in Patients with Lamivudine-Resistant Chronic Hepatitis B

Abstract

Adefovir (ADV) is the preferred drug for treating lamivudine (LAM)-resistant hepatitis B. However, not all patients who face virologic breakthrough during LAM treatment respond to ADV. The aim of this study was to determine the factors associated with efficacy of ADV in LAM-resistant hepatitis B patients. The medical records of 231 patients who received ADV due to LAM-resistance were reviewed. Efficacy was assessed by the initial virologic response (IVR), defined as hepatitis B virus (HBV) DNA not being undetectable by real-time PCR at 6 months of ADV treatment. Seventy patients (30%) achieved IVR. While 'add-on' modality, hepatitis B e antigen (HBeAg) negativity, and low baseline HBV DNA levels were associated with IVR in univariate analysis, multivariate analysis revealed HBeAg status and the DNA level to be the significant factors. The probability of IVR achievement increased sharply per each log(10) copies/mL decrement in the baseline viral load, which was 133 times in patients who had HBV DNA <10(5) copies/mL compared with those who had ≥10(8) copies/mL. Factors associated with the IVR were HBeAg negativity and a low baseline viral load. Therefore, when virologic breakthrough with genotypic resistance emerges during LAM therapy, ADV treatment should be considered immediately before further increases in viral load. Additional long-term follow-up data are warranted.