1000: Gestational age versus birthweight to predict outcomes in neonates with extreme prematurity

Abstract

Births < 28 weeks gestational age (GA) account for the majority of neonatal morbidity and mortality. GA mainly drives offering antepartum/delivery interventions; however, many institutions incorporate fetal weight estimate cut-offs below which intervention may not be offered. We aimed to evaluate the predictive value of birth GA and birthweight (BW), independently and combined, for neonatal mortality and morbidity in a contemporary cohort of extremely preterm infants. Secondary analysis of a multicenter RCT of umbilical cord milking vs delayed cord clamping in premature newborns (PREMOD2), with current analysis limited to newborns 230-276 weeks GA. The primary outcomes were neonatal death and a composite of severe neonatal morbidity (components in Figures). Multivariable logistic regression was used to model outcomes based on GA, BW, or both GA&BW as primary independent predictors. Receiver operator characteristics curves and area under the curve (AUC) were determined for the 3 models. AUCs were compared with contrast matrices to determine if GA, BW, or GA&BW had superior ability to predict the primary outcomes. Subgroup analysis for small for gestational age (SGA) infants was planned. Of 474 neonates in the parent trial, 182 (38%) were included in this analysis. Neonatal death occurred in 15% (n=27) and severe neonatal morbidity in 76% (n=139). For each outcome, GA or GA&BW had the highest AUCs. However, there was no significant difference between predictive value for neonatal death (AUCGA=0.85, AUCBW=0.85, AUCGA&BW=0.86) or severe morbidity (AUCGA=0.81, AUCBW= 0.80, AUCGA&BW = 0.82) between the 3 predictors (Figure 1). In the analysis of 25 (14%) SGA infants, there was similarly no difference in the predictive value based on GA, BW, or GA&BW for either primary outcome (Figure 2). GA and BW are both good predictors of neonatal morbidity and mortality in severely preterm neonates (with GA more predictive, but not significantly). Combining the two, however, is not more predictive than either alone, even in SGA infants.View Large Image Figure ViewerDownload Hi-res image Download (PPT)