Predictive Ability of Neonatal Illness Severity Scores for Early Death in Extremely Premature Infants

Background: The predictive ability of neonatal illness severity scores for mortality or morbidity in extremely premature infants has not been extensively studied. We aimed to evaluate the ability of neonatal illness severity scores [Clinical Risk Index for Babies II (CRIB II), Score for Neonatal Acute Physiology II (SNAP-II), and SNAP-Perinatal Extension II (SNAPPE-II)] in predicting mortality and short-term morbidity of extremely premature infants.

Methods: This retrospective study involved 171 infants with gestational age (GA) between 22 and 27 weeks who were admitted to the NICU during 2010-2017. Predictive ability of neonatal illness severity scores for mortality and short-term morbidity (bronchopulmonary dysplasia, retinopathy of prematurity, intraventricular hemorrhage, necrotizing enterocolitis, and gastrointestinal perforation) was assessed by comparing their area under the receiver operating characteristic curve.

Results: The overall mortality rate was 11.1%. Mortality at 23 weeks' gestation was higher than that at 24-27 weeks' gestation ( < .01, adjusted residual 4.5). Neonatal illness severity scores were significantly higher in infants who died than in those who survived ( < .01). CRIB II (AUC 0.93, 95% CI 0.85-1.00), SNAP-II (AUC 0.90, 95% CI 0.76-1.00), and SNAPPE-II (AUC 0.95, 95% CI 0.91-0.99) appeared to be excellent predictors and were superior to birth weight (AUC 0.88, 95% CI 0.80-0.95) or GA (AUC 0.84, 95% CI 0.72-0.96) alone in predicting early death (died on <28th postnatal day). CRIB II, SNAP-II, and SNAPPE-II were better predictors of early death than mortality in extremely premature infants. Neonatal illness severity score and short-term morbidity were not strongly associated.

Conclusions: The neonatal illness severity scores were excellent predictors of early death in extremely premature infants and might be useful for selecting extremely preterm infants who need intervention.