[Comparison of lamivudine-induced HBsAg loss rate according to age in children with chronic hepatitis B].

Background/aims: The aim of this study was to establish the characteristics of children with hepatitis B e antigens (HBeAg) positive chronic hepatitis B who were cleared of hepatitis B surface antigens (HBsAg) as a result of lamivudine treatment.

Methods: Seventy-six children with chronic hepatitis B who were seropositive for HBeAg were treated with lamivudine for at least 6 months. HBeAg seroconversion occurred during treatment in 49 of these children, who were then followed up to assess their clearance of serum HBsAg. Various clinical variables were compared between those patients who were cleared of HBsAg and those who were not, including age, pretreatment serum levels of alanine aminotransferase (ALT) and hepatitis B virus (HBV) DNA, treatment duration, the time elapsed between initiation of treatment and ALT normalization, HBV DNA negativization, HBeAg seroconversion, and HBsAg clearance.

Results: HBsAg disappeared in 13 of the 49 (26.5%) patients who experienced lamivudine-induced HBeAg seroconversion; HBsAg did not reappear during follow-up period (1-86 months). The time that elapsed between initiation of lamivudine treatment and total HBsAg clearance was 25.9+/-27.1 months (mean+/-SD; range: 5-104 months). The age at which treatment was initiated was the only factor associated with HBsAg clearance. Children who were cleared of HBsAg were significantly younger than those who were not (5.1+/-4.3 years vs. 7.9+/-4.9 years, respectively; P=0.006). All 13 of these patients eventually produced antibodies to HBsAg.

Conclusions: Younger children (age <7 years old) have a higher chance of HBsAg clearance than older children after the treatment of HBeAg-positive chronic hepatitis B with lamivudine.