Source Liver Research Unit, Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Taipei, Taiwan.
BACKGROUND & AIMS: Serum levels of hepatitis B surface antigen (HBsAg) decrease gradually during chronic hepatitis B virus (HBV) infection. We investigated the association between levels of HBsAg and HBsAg seroclearance.
METHODS: We studied data from 46 patients who underwent spontaneous seroclearance of HBsAg (median age at seroclearance, 48 years; 87% male; 76% infected with genotype B). Controls were 46 patients matched for age, sex, and HBV genotype, with persistently normal levels of alanine aminotransferase and were seropositive for HBsAg. Levels of HBsAg were assessed in serum specimens collected 5 years, 3 years, and 1 year before HBsAg seroclearance (or at the last examination, for controls).
RESULTS: The decrease in level of HBsAg was significant and accelerated within the 3 years before HBsAg seroclearance; there was no significant decrease in serum level of HBsAg among controls (P<.0001). The positive predictive value (PPV) for HBsAg seroclearance within 1 year was 36% among patients with HBsAg levels of 200 IU/mL, increasing to 44%, 54%, and 67% among those with 100 IU/mL, 50 IU/mL, or 10 IU/mL respectively; the negative predictive value (NPV) for these levels was ≥96%. The combination of HBsAg level <200 IU/mL and a decrease of ≥1 log10 IU/mL in a preceding 2-year period had PPVs of 97% and 100% for HBsAg seroclearance at 1 and 3 years, respectively; the NPVs were 100% and 92%, respectively.
CONCLUSIONS: The decrease in the level of HBsAg accelerates during the 3 years before HBsAg seroclearance. Levels of HBsAg ≤200 IU/mL have high NPVs for HBsAg seroclearance; PPVs increase to 97%-100% when combined with a ≥1 log IU/mL decrease in level of HBsAg over a 2-year period.