(15) Population Trends in Infant Mortality Before, During and After Implementation of Therapeutic Hypothermia as a Standard of Care

Janardhan Mydam, John H. Stroger Jr. Hospital of Cook County, Wheeling, IL, United States; Helen Atkinson, none, United States; Nitin Chouthai, Cardinal Glennon Children's Hospital, St. Louis,, MO, United States

Background: Moderate to severe hypoxic ischemic encephalopathy (HIE) is a major cause of mortality and lifelong morbidity. Following publication of the NICHD Neonatal Research Network (NRN) trial of therapeutic hypothermia (TH) in 2005, TH became standard of care for newborns with moderate to severe HIE. Data showing population-level time trends of survival among infants with intrauterine and/or birth asphyxia relative to the implementation of TH are lacking in the literature.

Objectives: To assess the impact of hypothermia treatment on the mortality of infants at risk for HIE by comparing mortality rates before, during, and after implementation of TH.

Design/Methods: We studied data from the National Center for Health Statistics (NCHS) period-linked US birth/infant death files for the years before (2000-2005), during (2006-2009) and after (2010-2018) the implementation of TH. We selected births with a 5-minute Apgar score ≤ 5 as a proxy indicator for intrauterine and/or birth asphyxia. We excluded infants with gestational age < 36 weeks, 5-minute Apgar score >5, and deaths related to causes other than asphyxia. We calculated disease-specific IMRs (deaths due to intrauterine and/or birth asphyxia) for each of the three time intervals (2000-2005, 2006-2009, 2010-2018). Deaths were further categorized by type of asphyxia: intrauterine, birth, and intrauterine and/or birth asphyxia. We used chi-square test to evaluate the differences in mortality rates across the three time intervals.

Results: The IMRs for our study population, regardless of type of asphyxia (intrauterine asphyxia and/or birth asphyxia) were 20.32 before (2000-2005), 5.71 during (2006-2009), and 4.18 after (2010-2018) implementation of hypothermia treatment (P < 0.001). Stratified by type of asphyxia, IMRs in the before, during and after periods were 2.81, 1.28, and 1.36 for infants with intrauterine asphyxia (P < 0.001) and 17.51, 4.42 and 2.28 for infants with birth asphyxia (P < 0.001).

Conclusion: In the United States, deaths related to intrauterine asphyxia and birth asphyxia have decreased significantly since implementation of TH.