Role of HBsAg levels in guiding hepatitis B virus prophylaxis in pregnancy: Insights from a multi‐ethnic cohort

Abstract

Pregnant mothers with chronic hepatitis B infection (CHB) need peri‐partum antiviral prophylaxis (PAP) to reduce the risk of mother‐to‐child‐transmission. Currently, PAP is recommended in those with high viral load (VL) that is, HBV DNA >200,000 IU/mL. Quantitative hepatitis B surface antigen (qHBsAg) >10,000 IU/mL, a cut‐off derived primarily from hepatitis B e‐antigen (HBeAg) positive antenatal cohorts in Chinese populations, is advocated as a surrogate marker of VL for guiding PAP. We investigated the utility of qHBsAg to predict high‐VL in a multi‐ethnic urban cohort with CHB. A consecutive cohort of women with CHB was identified from Barts Health NHS Trust databases in the United Kingdom. We included women with paired HBV DNA and qHBsAg during pregnancy. Women already on antiviral at conception were excluded. A total of 769 pregnancies in 678 CHB pregnant mothers (median age 31 years‐old, 8.6% HBeAg+) were included. At median gestational age of 15.3 weeks, HBV DNA was 336 (IQR 44–2998) IU/mL, with 65 (8.5%) being high‐VL. Serum qHBsAg was most useful in Black/Black‐British/Caribbean/African (AUROC 0.946) with 100% sensitivity and 80.6% specificity to predict high‐VL; but it performed less well for other ethnicities: Asian (AUROC 0.877), White (AUROC 0.797) and mixed ethnicities (AUROC 0.742). In conclusion, for settings where healthcare resources are not limited, HBV DNA remains the optimal marker to identify highly viraemic pregnancies for guiding PAP. For resource‐limited settings where the prevailing cost is treatment, serum qHBsAg can be used in Black/Black British/Caribbean/African sub‐cohorts, but not for other ethnicities.