Association between Congenital Anomalies and Late-Onset Bacterial Infections in Neonates Admitted to Neonatal Intensive Care Units in Australia and New Zealand: A Population-Based Cohort Study

Introduction: Compromised neonatal intensive care unit neonates are at risk of acquiring late-onset infections (late-onset sepsis LOS). Neonates born with congenital anomalies (CAs) could have an additional LOS risk. Methods: Utilising the population-based Australian and New Zealand Neonatal Network data from 2007 to 2017, bacterial LOS rates were determined in very preterm (VPT, 32 week), moderately preterm (MPT, 32–36 weeks), and term (FT, 37–41 weeks) neonates with or without CA. Stratified by major surgery, the association between CA and bacterial LOS was evaluated. Results: Of 102,808 neonates, 37.7%, 32.8%, and 29.6% were born VPT, MPT, and FT, respectively. Among these, 3.4% VPT, 7.5% MPT, and 16.2% FT neonates had CA. VPT neonates had the highest LOS rate (11.1%), compared to MPT (1.8%) and FT (1.8%) neonates. LOS rates were higher in CA neonates than those without (8.2% versus 5.1% adjusted relative risk aRR 1.67, 95% confidence interval CI: 1.45–1.92). Neonates with surgery had a higher LOS rate (14.2%) than neonates without surgery (4.4%, p 0.001). Among the neonates without surgery, CA neonates had consistently higher LOS rates than those without CA (VPT 14.3% vs. 9.6% aRR 1.32, 95% CI: 1.11–1.57; MPT 4% vs. 0.9% aRR 4.45, 95% CI: 3.23–6.14; and FT 2% vs. 0.7% aRR 2.87, 95% CI: 1.97–4.18). For the neonates with surgery, CAs were not associated with additional LOS risks. Conclusion: Overall, we reported higher rates of LOS in neonates with CA compared to those without CA. Regardless of gestation, CA was associated with an increased LOS risk among non-surgical neonates. Optimisation of infection prevention strategies for CA neonates should be explored. Future studies are needed to evaluate if the infection risk is caused by CA or associated complications.