Inter-ethnic differences of quantitative hepatitis B surface antigen (qHBsAg) in predicting highly viraemic pregnancy with chronic hepatitis B infection

Abstract

Background & Aims: Pregnant mothers with chronic hepatitis B infection (CHB) need antiviral prophylaxis if they have high viral load, defined as HBV DNA >200,000 IU/ml or qHBsAg levels >10,000 IU/ml – a cut-off derived primarily from high-risk hepatitis B e-antigen (HBeAg) positive antenatal cohorts in Taiwan and China. We investigated the utility of qHBsAg to predict highly viremic pregnancy in a multi-ethnic urban cohort with CHB. Approach & Results: A consecutive cohort of women with CHB were identified from Barts Health NHS Trust databases and prospectively collected by screening midwives across the Trust. We included women with paired HBV DNA and qHBsAg during pregnancy between December 2012-February 2022. Women already on antiviral treatment 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 a median gestational age of 15.3 weeks, HBV DNA was 318 (IQR 39-2969) IU/mL, with 65 (8.5%) pregnancies being highly viremic. Serum qHBsAg was most useful in Black/Black-British/Caribbean/African (area under receiver-operating characteristic curve [AUROC] 0.946), and a cut-off level of 4 logs was 100% sensitive and 80.6% specific to predict highly viremic pregnancy. Comparatively, qHBsAg performed least well for White subjects (AUROC 0.797), and the same cut-off level was 71.4% sensitive and 89.2% specific to predict highly viremic pregnancy. HBV DNA profile at the index pregnancy was 100% consistent with subsequent pregnancy. Conclusions: Serum qHBsAg can predict highly viremic pregnancies in Black/Black British/Caribbean/African patients but it’s utility in Caucasian CHB patients is less clear.