Refining the Apgar score cut-off point for newborns at risk

Abstract

Aim: To evaluate the Apgar score predictive power for mortality during different periods in the first year of life in a population with a very low mortality rate. Methods: The records of all singleton live births without severe congenital malformations and length of gestation >25 wk (n = 976635) were collected from the Swedish Medical Birth Registry, 1990 to 1998. Receiver operating characteristic (ROC) analysis was utilized. Results: Both the 1-min and the 5-min Apgar scores were shown to be good discriminators for early mortality, with the area under the ROC curve >0.85. For babies at risk of early death, the selected cut-off values for the 1-min Apgar score was <8 for preterm (true-positive (TP) rate: 83.9%; false-positive (FP) rate: 17.7%) and term babies (TP rate: 69.4%; FP rate: 6.7%). At 5 min, the analysis revealed that newborns with an Apgar score <9 were at risk for early death (preterm babies: TP rate: 79.8%; FP rate: 13.3%; term babies: TP rate: 73.8%; FP rate: 3.4%). Conclusions: Our analysis did not support the common practice in the clinic or in research of grouping infants at risk in Apgar score groups, i.e. a score below 4 or a score below 7. However, the data presented here allow the clinicians and researchers to identify and define a suitable cut-off point in relation to the quality of neonatal care and resources available, rather than adhering to a historical cut-off value that has not been studied in depth.