A prospective study of the evolution of lamivudine resistance mutations in patients with chronic hepatitis B treated with lamivudine

Summary.  Lamivudine resistance has been described in subjects with chronic hepatitis B infections, associated with mutations in the viral polymerase gene. The objective of this study was to estimate the emergence rate of lamivudine‐resistant viral strains and their consequences over a 2‐year period. We evaluated 283 lamivudine‐naïve subjects with chronic hepatitis B. Clinical and virological features were assessed at inclusion and every 6 months thereafter. Viral DNA was characterized using polymerase chain reaction (PCR)‐based sequencing. Potential risk factors for the emergence of lamivudine resistance mutations were assessed using logistic regression analysis. The annualized incidence rate for viral polymerase mutations was 22%. The only independent risk factor identified was high viral load, at inclusion. Detectable viral DNA and elevated transaminases were more frequent in subjects harbouring mutant viral strains, and these underwent a lower rate of hepatitis B e seroconversion. All subjects responded favourably to treatment, with no difference in symptoms between the two groups. This prospective cohort study identified lamivudine‐resistant mutations emerging in 22% of subjects, yearly, which were apparently not associated with clinical aggravation over the study period.