Journal Review

by William Clark, MD

Casey BM. McIntire DD, Leveno KJ. The continuing value of the Apgar score for the assessment of newborn infants. New Engl J Med 2001; 344(7): 467-471.

Introduction: The 10-point Apgar score has been used worldwide to assess the condition and prognosis of infants for almost 50 years. The value of Apgar scores has been questioned because of attempts to use it as a predictor of neurologic development, for which it was never intended. Some investigators propose that pH measurement in umbilical-artery blood is a more objective method of assessing newborns. This study examined whether the original intent of the Apgar system, to predict survival during the neonatal period, remains pertinent.

Methods: This was a retrospective cohort analysis of 151,891 live–born singleton infants without malformations who were delivered at >26 weeks’ gestation at an inner-city hospital between January 1988 and December 1998. Paired Apgar scores and umbilical-artery blood pH values were available for 145,627 infants. The primary outcome measure was death in the first 28 days of life.

Results: Of the 13,399 preterm infants (26–36 weeks’ gestation) with 5-minute Apgar scores of 0–3, the neonatal mortality rate was 315/1000 infants, compared to a rate of 5/1000 for preterm infants with 5-min. Apgar scores of 7–10. For 132,228 term infants (>37 weeks’ gestation), the mortality rate was 244/1000 for infants with 5-min. Apgar scores of 0–3 compared with a mortality rate of 0.2/1000 infants with 5-min. Apgar scores of 7–10. The risk of neonatal death in term infants with 5-min. Apgar scores of 0–3 (relative risk, 1460; 95% CI, 835–2555) was 8 times the risk in term infants with umbilical-artery blood pH values <7.0 (relative risk 180; 95% CI, 97–334). The severity of umbilical-artery acidemia did not appreciably modify the relative risk of neonatal death associated with 5-min. Apgar scores of <3 in either preterm or term infants. But, a combination of 5-min. Apgar scores <3 and pH value <7.0 did increase the risk of neonatal death in both preterm and term infants. The relative risk of neonatal death in term infants with 5-min. Apgar scores <3 and umbilical-artery blood pH of <7.0 was 3204 (95% CI 1864–5508).

Discussion: This large study enrolled over 150,000 infants in 10 years. One study limitation is the few infants with a 5-min. Apgar score <3 (178 of the 145,627 study infants). However, study results suggest that a very low 5-min. Apgar score (0–3), although rare, remains strongly predictive of early neonatal death. Another study limitation is the 6264 infants from whom umbilical-artery blood gas values were not available. These infants had an incidence of neonatal death of 4.5/1000 compared with 1.2/1000 in infants for whom blood gas analysis was performed. Finally, possible differences in treatment of very immature infants might alter the predictive value for low Apgar scores in this cohort. For example, very immature infants with very low Apgar scores might have been treated less aggressively than infants of similar maturity with higher Apgar scores. This would potentially overestimate the value of very low Apgar scores as a predictor of neonatal mortality in this group.

In 1952, Apgar reported that neonatal survival through 28 days was related to the condition of the infant in the delivery room. This study results validate that the Apgar scoring system remains a good predictor of neonatal mortality.