51 - Population Trends in Infant Mortality Before, During, and After Implementation of Therapeutic Hypothermia Across Racial and Ethnic Groups: United States Period-Linked Data, 2000–2017

Publication Number: 1044.51

Janardhan Mydam, John H. Stroger Jr. Hospital of Cook County, Chicago, USA, CHICAGO, IL, United States; Nitin Chouthai, Oakland University William Beaumont School of Medicine, Dearborn, MI, United States

Background: Moderate to severe hypoxic-ischemic encephalopathy (HIE) remains a major cause of neonatal mortality and lifelong morbidity. Following publication of the NICHD Neonatal Research Network trial in 2005, therapeutic hypothermia (TH) became the standard of care for infants with moderate to severe HIE. However, national trends in HIE-related infant mortality before, during, and after TH implementation across racial and ethnic groups have not been comprehensively evaluated.

Objective: To assess the impact of therapeutic hypothermia on HIE-related infant mortality by comparing mortality rates before (2000-2005), during (2006-2009), and after (2010-2017) implementation of TH among different racial and ethnic groups in the United States.

Design/Methods: We analyzed period-linked U.S. birth and infant death data from 2000-2017. Infants with a 5-minute Apgar score ≤ 5 were used as a proxy for intrauterine or birth asphyxia. We excluded infants < 36 weeks' gestation, with Apgar > 5, or deaths unrelated to asphyxia. Disease-specific infant mortality rates (IMRs) were calculated for Latina, non-Latina Black, and non-Latina White populations. Univariable and multivariable logistic regression models were used to estimate odds ratios (ORs) and 95% confidence intervals (CIs), adjusting for maternal race/ethnicity and nativity, age, marital status, prenatal care, infant sex, hypertension, diabetes, parity, gestational age, and Apgar score. Non-Latina White mothers served as the reference group.

Results: Disease-specific IMRs due to birth asphyxia declined consistently across all racial and ethnic groups. Among Latina mothers, IMR decreased from 14.65 (before) to 3.05 (after). Among non-Latina Black mothers, IMR declined from 12.46 to 2.15, and among non-Latina White mothers, from 13.15 to 2.40. In multivariable analysis, the odds of disease-specific infant mortality were significantly lower after TH implementation. Compared with non-Latina White mothers, non-Latina Black mothers had 52% lower odds of asphyxia-related infant mortality after TH implementation (OR = 0.48; 95% CI 0.30-0.76).

Conclusion(s): Following the implementation of therapeutic hypothermia, infant deaths due to birth asphyxia have decreased substantially across all racial and ethnic groups in the United States. The most pronounced decline was observed among non-Latina Black infants, suggesting a potential narrowing of racial disparities in HIE-related mortality after adoption of TH as standard care.

Fig.1 Trends in hypoxic-ischemic encephalopathy-related infant mortality before (2000-2005), during (2006-2009), and after (2010-2017) implementation of therapeutic hypothermia across racial and ethnic groups, United States 2000-2017.


Table 1. Univariable and multivariable logistic regression models of hypoxic-ischemic encephalopathy-related infant mortality before (2000-2005), during (2006-2009), and after (2010-2017) implementation of therapeutic hypothermia among racial and ethnic groups in the United States, 2000-2017.