Incidence and determinants of spontaneous seroclearance of hepatitis B e antigen and DNA in patients with chronic hepatitis B

Abstract

Background & aims: The spontaneous seroclearance of hepatitis B e antigen (HBeAg) and hepatitis B virus (HBV) DNA are important markers of progression of chronic HBV infection. We performed a long-term cohort study to elucidate the incidence and determinants of HBeAg and HBV DNA seroclearance in patients with chronic hepatitis B.

Methods: A total of 1289 participants with a serum HBV DNA level of 10,000 copies/mL or more and without cirrhosis when the study began (1991-1992) were followed up until June 2004. A subset of patients that tested positive for HBeAg at baseline (n = 439) was included in the analysis of HBeAg seroclearance. Cox proportional hazards models were used to estimate seroclearance rate ratios for various determinants associated with the outcomes.

Results: After 3161.2 person-years of follow-up evaluation, HBeAg seroclearance occurred in 187 participants (incidence rate, 5.9 per 100 person-years). The cumulative lifetime incidence of HBeAg seroclearance among patients who were 30 to 40, or 50, 60, 70, or 74 years old was 38.8%, 69.4%, 81.9%, 89.1%, and 95.5%, respectively. Major predictors of HBeAg seroclearance included female sex, genotype B, the precore 1896 mutant, increased serum levels of alanine aminotransferase, and low baseline serum levels of HBV DNA. The median (interquartile range) serum level of HBV DNA at the time of HBeAg seroclearance was 177,801 copies/mL (4941-3,247,560 copies/mL). HBV DNA seroclearance occurred in 199 participants (15.4%) during the mean follow-up period of 7.8 years (incidence rate, 1.97 per 100 person-years). The cumulative lifetime incidence of HBV DNA seroclearance at 40, 50, 60, 70, and 77 years old was 10.0%, 25.0%, 38.8%, 54.2%, and 82.8%, respectively. Lower levels of HBV DNA at study entry and among those with the precore 1896 wild-type variant were associated with an increased rate of HBV DNA seroclearance. Among individuals who were HBeAg-seropositive at study entry and cleared serum HBV DNA during the follow-up period, 89% had cleared HBeAg by the time they had an undetectable serum level of HBV DNA.

Conclusions: Serum level of HBV DNA is the most important predictor of seroclearance of HBeAg and HBV DNA. This finding supports current clinical guidelines for antiviral treatments of chronic hepatitis B.