6317 Apgar score and the risk of cause-specific neonatal mortality: a population-based cohort study

Objectives In preterm infants the predictive and discriminative validity of the Apgar score regarding neonatal mortality and cause-specific neonatal death remains uncertain.¹–³ Methods Population-based study using Scottish National Health Service administrative linked data of all births in Scotland between 1st January 2007 and 31st December 2019. Apgar score was assessed and recorded at 5-min after birth into one of three categories: low (Apgar score of 0–3), intermediate (Apgar score of 4–6), and normal (Apgar score of 7–10). The primary outcome was overall and cause-specific neonatal mortality based on WHO's application of the ICD-10 system for mortality in the perinatal period.⁴ We used multivariable Poisson regression models with a robust sandwich estimator to determine adjusted absolute risks and relative risks (RRs) for Apgar score categories. Results Over the period from January 1, 2007, to December 31, 2019, a total of 677,520 infants were delivered in Scotland, with 39,676 of them born prematurely. There were 521 neonatal deaths (1.3%) in total. The predominant causes of neonatal deaths included respiratory and cardiovascular disorders (n=203, 0.5%), complications arising from low birthweight and prematurity (n=179, 0.5%), and congenital malformations (n=142, 0.4%). As gestational age increased the adjusted relative risk of neonatal death increased substantially for babies with low scores compared to those with medium or high Apgar scores (figure 1). For instance, among infants born at 22 to 24 weeks with a low Apgar score, the relative risk of neonatal death was 5.7 (95% CI 3.2–10.13, p<0.001) times greater compared to those with high Apgar scores. In contrast, for infants born at 35 or 36 weeks, the corresponding relative risk was significantly higher, exceeding 80 (95% CI 56.89–112.61, p<0.001) times. The Apgar score remained informative for extremely preterm infants and discriminated between deaths due to prematurity (RR22–24 wk 12.26 (95%CI 5.1, 29.48, p-value <0.001)) and maternal factors leading to death (RR22–24 wk 3.47 (95%CI 1.13, 10.62, p-value = 0.03)) for babies with low Apgar score compared to high. However, as gestational age increased the Apgar score became less discriminatory for specific causes of death. Conclusion Apgar score is a valuable prognostic tool for neonatal mortality, even among extremely preterm infants. At extreme prematurity, the APGAR score can also discriminate cause-specific deaths however this diminishes as gestational age increases. References The Apgar score, American College of Obstetricians and Gynecologists 2015. Iliodromiti S, et al. Apgar score and the risk of cause-specific infant mortality: a population-based cohort study 2014. Cnattingius S, et al. Apgar Score and Risk of Neonatal Death among Preterm Infants 2020. World Health Organization. WHO's application of the ICD-10 coding system for neonatal deaths 2016.