CRIB score, birth weight and gestational age in neonatal mortality risk evaluation

Objective To evaluate the mortaliry rate of very low birth weight babies born at a Neonatal Intensive Care Unit (NICU) during a specified period of time according to variations in CRIB (Clinical Risk Index for Babies) score, birth weight and gestational age. Methods From January 1997 to December 2000, the CRIB score was prospectively applied to all newborn infants admitted to the NICU of an university hospital of Londrina, Brazil, with birthweight under 1, 500 g and/or gestational age of less than 31 weeks. The exclusion criteria were: death before 12 hours of life, presence of lethal congenital malformations and newborns who had been referred from other hospital. Results Two hundred and eighty-four infants met the inclusion criteria. Mean birth weight was 1, 148 248 g (median = 1, 180), mean gestational age was 30.2 +/- 2.4 weeks (median = 30.0) and mean CRIB score was 3.8 +/- 4.4 (median = 2.0). The neonatal mortality rate was 23.2%, varying according to mean birthweight <750 g (72.7%), gestational age <29 weeks (57.1%) and CRIB score >10 (79.4%). Receiver Operating Characteristic (ROC) curves were composed for CRIB score, birth weight and gestational age to assess the ability of each to predict hospital mortality and the areas under the curve were respectively 0.88, 0.76 and 0.81. Sensitivity, specificity and predictive values were evaluated and all variables were considered predictors of mortality (p<0.0001). The optimal cut off point based on the ROC curve for the CRIB score was 4 with sensitivity 75.8%, specificity 86 7, positive predictive value 63.3% and negative predictive value 92.2%. Conclusions In this study infants with birthweight of less than 750 grams, less than 29 weeks gestational age and CRIB scores above 10 had higher mortality rates. However a CRIB score higher than 4 proved to be a better predictor of mortality when compared to birthweight and gestational age.