A predictive value of quantitative HBsAg for serum HBV DNA level among HBeAg-positive pregnant women.

ABSTRACT

BACKGROUND: The high maternal HBV DNA level is the most important factor contributing to HBV perinatal transmission. This study is to explore whether HBsAg can be used as a surrogate marker of serum HBV DNA for HBsAg-positive pregnant women. METHODS: A total of 975 HBsAg-positive pregnant women and their infants were enrolled in this study. All infants received three doses of a yeast-derived recombinant Hepatitis B vaccine at 0, 1 and 6 months. They were also given Hepatitis B immunoglobulin (HBIG) at birth. HBsAg and HBeAg were determined using Abbott Architect assays while serum HBV DNA level was detected by the Abbott Real Time HBV DNA assay. RESULTS: Of the 975 subjects, 367 (37.6%) were HBeAg-positive and 608 (62.4%) were HBeAg-negative. Among the HBeAg-positive group, the samples with HBV DNA levels of ≥7.0 logIU/mL were 76.6% (281/367), and it was only 0.7% (4/608) for the HBeAg-negative group. HBV DNA level was positively correlated with HBsAg in HBeAg-positive group (r=0.786, p<0.001) but not in HBeAg-negative group (r=0.022, p=0.593). Among HBeAg-positive group, the area under the receiver-operator curve (ROC) of HBsAg titer for high HBV DNA level (≥7.0 logIU/mL) was 0.961 (95% CI, 0.940-0.983, p<0.001). The optimum cut-off point HBsAg titer above 4.1 logIU/mL had a sensitivity of 85.1%, specificity of 96.5%, and accuracy of 87.5% to predict HBV DNA levels of ≥7.0 logIU/mL. Of 367 infants born to mothers with HBeAg-positive, perinatal transmission was detected in 24 infants (6.5%, 24/367). Their mothers all had serum HBV DNA levels of ≥7.0 logIU/mL, 23 (95.8%) had HBsAg titers of ≥4.1 logIU/mL and the other mother had HBsAg titer of 3.9 logIU/mL. Of 608 infants born to mothers with HBeAg-negative, only one (0.2%, 1/608) became HBsAg-positive at the age of 7 months, and the mother of the infant had serum HBV DNA level of 3.4 logIU/mL and HBsAg titer of 1.8 logIU/mL, respectively. CONCLUSION: Serum HBsAg titer may be used as a surrogate marker of serum HBV DNA for HBeAg-positive pregnant women.