Comparação das curvas de crescimento Fenton & Kim e INTERGROWTH-21st na classificação de prematuros

Abstract

Prematurity and low birth weight are important predictors of neonatal morbidity and mortality. Premature newborns correctly classified with an adequate growth curve, allow that specific care is applied in order to avoid consequences, often irreversible. The present study aimed to compare the agreement in the classification, according to weight for the gestational age of preterm infants at birth using the Fenton & Kim and INTERGROWTH-21st growth curves. A retrospective longitudinal study was conducted using registers of premature babies born between 2009 and 2019 in a hospital for high-risk pregnant women in the city of Rio de Janeiro. From data on birth weight and gestational age, z scores were calculated using the calculation tools provided by the two curves studied. Accordingly, preterm infants were classified in: SGA that newborn with weight <-2 Z score, AGA that with weight between -2 and +2 Z score and LGA that with weight> +2 Z score. To facilitate the comparison of results, preterm infants were categorized by degree of prematurity into: late / moderate (between 32 weeks of gestational age and 36 weeks and 6 days) and severe / extreme (less than 32 weeks of gestational age). To agreement between the curves, was measured by weighted Kappa coefficient and a 95% confidence interval. Among the 1296 preterm infants analyzed it was observed that the curve INTERGROWTH-21st classified a higher percentage of newborn as SGA than the Fenton & Kim curve, particularly in the severe / extreme category (21.6% vs. 9.6%). When comparing the agreement between the classifications, in the total number of preterm infants, there was a moderate agreement between the curves with a Kappa coefficient of 0.66 (p value <0.0001). Agreement was higher in the late / moderate category and it was lower in the severe / extreme category. Classifications were also analyzed as a possible predictor of mortality. The agreement of the classifications among the premature infants who died during the hospitalization period showed a moderate agreement between the curves. Of the 74 preterm infants classified as PIG by the Fenton & Kim curve, 10.8% died, and of the 134 preterm infants classified by the INTERGROWTH-21st curve, 15% died, that is, discordant preterm infants were placed in the AIG category on the curve Fenton & Kim. Based on these results, it was concluded that the INTERGROWTH-21st curve was able to identify a greater number of SGAs in premature newborns and suggest that this curve is the best predictor of neonatal mortality since it was able to identify a greater number of PIGs among deaths in this population. Other studies with larger samples, if the results obtained are confirmed, may show the superiority of the INTERGROWTH-21st curve, either for epidemiological evaluation or for use in health services.