353 - Evaluating the Incidence of HIE in a Contemporary Cohort: Trends in Diagnosis And Disease Severity

Publication Number: 353.5025

Melissa Schmatz, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, United States; Sara Handley, Childrens Hospital of Philadelphia, Philadelphia, PA, United States; Kathryn McKenney, University of Colorado School of Medicine, Aurora, CO, United States; Heather H. Burris, Children's Hospital of Philadelphia, Philadelphia, PA, United States; Evan Miller, Nemours Children's Hospital, Newark, DE, United States; Moeun Son, Weill Cornell Medicine, New York, NY, United States; Jennifer Culhane, Yale School of Medicine, New haven, CT, United States; Jay S. Greenspan, Sidney Kimmel Medical College at Thomas Jefferson University, Voorhees, NJ, United States; Kevin Dysart, Nemours Children's Hospital, PHILADELPHIA, PA, United States

Background: Despite advances in obstetric and neonatal care, hypoxic ischemic encephalopathy (HIE) remains a leading cause of infant morbidity and mortality. Several recent cohort studies illustrate an increase in HIE diagnosis with an associated increased utilization of therapeutic hypothermia over time. However, these studies differ in identifying incidence of HIE and consistent trends of HIE severity.

Objective: To evaluate trends of HIE incidence and severity from 2017-2023 in a national database.

Design/Methods: This retrospective cohort study employed Epic Systems Cosmos research database, which uses aggregated electronic medical record data. Infants born between 1/1/2017 and 12/31/2023 and cared for in an organization with coding indicators of neonatal intensive care were included in analysis (N=537). HIE was identified and severity graded by ICD-10 codes in infants ≥35 weeks’ gestation. Poor biochemical indicators (pH≤7, base deficit (BD) ≥15) and 10-minute Apgar score ≤ 5 were used as additional proxies for severe disease. Statistical analysis included chi-square test for categorical variables and Mann Whitney U test for continuous variables.

Results: Among 3,705,378 eligible infants, 5,561 were ≥35 weeks with any HIE diagnosis. Infants with severe HIE were more likely to male, delivered via Cesarean birth, have poor biochemical markers, ten-minute Apgar score ≤5, seizures in the NICU, and birthing parents who experienced severe maternal morbidity (Table 1). During the study period, HIE incidence increased from 1/1000 live births in 2017 to 1.9/1000 in 2023 (P < 0.001) (Figure 1). While this increase was seen across all gestational ages, late preterm (35-36 weeks) and post-dates infants (41-42 weeks) saw a more significant increase over time (Figure 2). Additionally, the severity of HIE increased over time, both by ICD-10 code grading and the proxies of poor biochemical markers and low ten-minute Apgar score.

Conclusion(s): In this cohort, we found an increase of HIE incidence throughout study duration. In contrast to previous studies that identified an increase in mild HIE diagnosis as likely etiology for rising HIE incidence, our data suggest that patients with moderate or severe HIE and HIE with proxy disease severity indicators have increased over time. While these data suggest that patients with HIE are more ill, it may also represent heightened HIE awareness and laboratory screening by clinicians. Further analysis of drivers of these trends are needed to optimize HIE treatment and prevention.

Table 1: Birth parent and infant characteristics by severity of hypoxic ischemic encephalopathy grade


Figure 1: HIE Rate Among Infants 35-42 Weeks EGA by Year


Figure 2: HIE Rate Among Infants 35-42 Weeks EGA By Year And Gestational Age