Predicting hepatitis B e Antigen seroconversion after pregnancy-The SydPregScore

Background and Aims: Achieving Hepatitis B e antigen seroconversion (HBeAg SC) at an earlier age confers a better prognosis. We examined baseline and postpartum factors associated with HBeAg SC after pregnancy. We developed a tool, the SydPregScore, to estimate the likelihood of HBeAg SC in the years after pregnancy. Methods: A retrospective analysis of an HBeAg-positive pregnant cohort was conducted. Variables including baseline age, parity, alanine aminotransferase level, HBV viral load, quantitative HBsAg, use of antiviral therapy and post-partum flare were collected. Univariate and multivariate Cox regression analyses to determine predictors of HBeAg SC and develop a predictor score were performed. Results: We analysed HBeAg SC rates in 220 pregnancies to 149 HBeAg-positive women from 2006 to 2019. At baseline, their median age was 33 (IQR 29-37), ALT 23 U/L (IQR 17-33) and viral load 8 log(10) IU/mL (IQR 6.3-8.2 log(10) IU/mL). The majority (133/198, 67.2%) received short-course antiviral therapy to prevent mother-to-child transmission, and 109/192 (56.8%) had a post-partum flare. HBeAg SC occurred in 74/220 (33.6%) after pregnancy (median follow-up 814days, IQR 405-1531). Multivariate analysis identified baseline viral load <8 log(10) IU/mL (HR 2.426 [1.224-4.809], p = .011), baseline ALT >= 2 ULN (HR 2.726 [1.299-5.721], p = .008) and age <35 (HR 2.859 [1.255-6.513], p = .012) to be positive predictors of HBeAg SC. The 'SydPreg Score' estimated the probability of HBeAg SC at 2000days as 10%, 30%, 70% and 80% for 0, 1, 2, and 3 predictors respectively. Conclusion: The SydPreg Score allows the prediction of HBeAg SC in the years after pregnancy. Even in those without elevated ALT, age <35 and viral load <8 log(10) IU/mL can identify women with a good chance of subsequent HBeAg SC. Those without a chance may benefit from viral suppression.