Quantitative hepatitis B virus DNA testing for the early prediction of themaintenance of response during lamivudine therapy in patients with chronichepatitis B

To determine whether a dramatic decrease in hepatitis B virus (HBV) DNA lev els within the first months of lamivudine therapy can predict the emergence of YMDD variants in patients with chronic hepatitis B, quantitative testin g was done every 3 months on serum samples from 35 patients who were treate d with lamivudine for >1 year. The decline in HBV DNA levels from baseline to month 3 was higher in 22 responders than in 13 nonresponders (mean +/- S D, 4.16 +/- 1.06 vs 2.88 +/- 1.77 log(10) copies; P = .002), whereas no dif ferences were observed in patients with and without YMDD variants at 1 year of therapy. At 3 months, HBV DNA was undetectable in 77% of the responders , whereas, after 1 year, it was undetectable in 23% of nonresponders, 40% o f patients with YMDD variants, and 74% of those without variants. Therefore , quantitative HBV DNA testing is very useful in deciding whether to contin ue therapy, because of the low likelihood of response in patients who remai n HBV DNA positive at month 3 of treatment.