100 - Trends and Racial Disparities in Infant Mortality Associated with Hypoxic Ischemic Encephalopathy in the United States

Neonatal hypoxic ischemic encephalopathy (NE) caused by decreased cerebral perfusion and hypoxic injury is one of the leading causes of neurodevelopmental disability and mortality in infants. However, there is scant population level data for NE-specific infant mortality rates (NE-IMR) during therapeutic hypothermia (TH) implementation era in United States.

Objective:

To report incidence of NE-IMR by live births; and to compare the overall and race-specific trends by annual percentage change (APC) estimates.

Design/Methods: We used US Centers for Disease Control and Prevention (CDC)-WONDER linked birth/infant database that provides counts for deaths of infants < 1 year of age from 2007-2019. The incidence rate of NE-IMR per 100,000 live births was calculated using annual births as denominator and we included any infant who had hypoxic ischemic encephalopathy (HIE - ICD 10 Code: P91.6 ) as cause of death. We analyzed mortality rate differences by maternal race, sex, mode of delivery and birth weight, and presented Odds Ratios (OR) with 95% confidence intervals (CI). A secondary analysis was carried out to include available data by gestational age (GA) from 2015-2020. We used descriptive statistics and Joinpoint regression with best-fit model to evaluate IMR trends as APCs with statistical significance set at p< .05.

Results: From 2007 to 2019, among 51,839,822 births, there were 2,456 deaths related NE with median NE- IMR of 4.9 (IQR: 4.1, 5.6) per 100,000 live births. Overall NE-IMR for White, Black, and Asian races were 4.5 (95% CI: 4.3, 4.7), 5.7 (95% CI: 5.2, 6.3) and 4.6 (95% CI: 3.8, 5.6), respectively. Compared to White infants, Black infants had higher (OR 1.26. 95% CI: 1.14, 1.4) mortality rate [Figure 1]. When trends were stratified by race, APC for White and Black infants were 6.3% (95% CI: 4.5, 8.2; p< .001) and 5.9% (95% CI: 3, 8.8; p=.001), respectively. Overall, we observed significant increase in HIE related infant mortality (APC 6.2%, 95% CI: 4.5, 7.9; p< .001) [Figure 2]. Subgroup analysis of infants born at GA >36 weeks showed overall APC of 7.7% [95% CI: 2.5, 13.1, p=.001]. [Figure 3]

Conclusion(s): Overall NE-IMR increased among US infants who had diagnosis of HIE in United States in last two decades. Compared to White infants, odds of risk for death are 25% higher in Black infants with HIE in the first year of life while NE-IMR increased for both the races over time. Further studies are warranted to understand the diagnostic coding patterns, nationwide incidence rates of HIE, TH use for HIE, impact of implementation of evidence-based TH practices for targeted population.