April 17, 2008

Nearly 600,000 babies were born premature in the U.S. in 2006 for a total societal cost of more than $26 billion (Source: “Births: Preliminary Data for 2006,” Centers for Disease Control, December 5, 2007; “Preterm Birth: Causes, Consequences, and Prevention,” IOM, July 13, 2006). 

These infants experience an increased risk of death or serious sequellae as compared to their full term counterparts.  Physicians traditionally assess risk as a function of gestational age however, this measurement can be subject to error, underestimating or overestimating gestational age by one or two weeks.  A new study published in the New England Journal of Medicine (Source: “Intensive Care for Extreme Prematurity – Moving beyond Gestational Age,” New England Journal of Medicine, 358(16), April 17, 2008) identifies other factors that predict the likelihood of complications or death for these babies.  Researchers with the National Institute of Child Health and Human Development Neonatal Research Network studied 4446 infants born between 22 and 25 weeks gestational age (gestational age at birth is typically 40 weeks) for factors impacting the likelihood of specific birth outcomes: survival without impairment, survival with impairment, survival with profound impairment, and death. 

Researchers identified four factors impacting the birth outcomes of these extremely premature infants, each resulting in a significant reduction in death or impairment and associated with as much as a one-week increase in gestational age:
• female sex
• singleton birth
• mother’s use of antenatal corticosterioids in the week prior to delivery
• higher birthweight (per each 100-g increment)

This method was better at predicting outcomes than the traditional method of gestational age alone.  As a result, physicians were able to deliver increasingly individualized, systematic, cost effective, and transparent treatment.  Researchers developed an online screening tool, Extremely Preterm Birth Outcome Data, based on these four factors to assess the likelihood of a child’s survival.  Rainbow Babies & Children’s Hospital was one of 19 study sites participating in this landmark study. 

The study raises several important issues for policy and practice including:
• whether the findings should be adapted in neonatal intensive care units as a standard of care
• whether the data, drawn from tertiary care centers, are applicable to other settings
• the potential for use of the risk prediction model as a basis for outcome evaluations and potentially as an input for pay-for-performance assessments