Intergrowth versus Fenton: há diferença na concordância do indicador de peso para idade gestacional ao nascimento e durante o internamento hospitalar?

Abstract

Introduction – Preterm birth is the leading cause of mortality in children under five years of age, with substantial impacts on growth and child development. Preterm infants face considerable nutritional risks due to biological immaturity and high metabolic demands, requiring accurate nutritional assessments to guide interventions. However, the lack of consensus regarding which neonatal growth chart to use (Fenton, INTERGROWTH, or Olsen) precludes diagnostic standardization. Discrepancies among these charts may result in divergent classifications of the nutritional status of preterm infants, with potential clinical consequences. Objective: To assess the concurrence between Fenton, INTERGROWTH, and Olsen growth charts in classifying the nutritional status of preterm newborns, both at birth and during hospitalization, and to examine their implications for nutritional diagnosis and their association with body composition. Methods – This dissertation was based on two retrospective observational studies. The first study included 2,529 preterm infants admitted to public neonatal units in Salvador, Brazil (2018-2021), and assessed the concurrence of weight-for-gestational-age Z-scores at birth between Fenton and INTERGROWTH charts. Bland-Altman plots were used, with stratified analyses by gestational age and birth weight adequacy, both individually and jointly. The second study involved 258 preterm infants hospitalized in four U.S. neonatal units (2012-2023). It compared Fenton, INTERGROWTH, and Olsen charts regarding the diagnosis of malnutrition during hospitalization, based on changes in weight Z-scores and their association with body composition measured by air displacement plethysmography (fat-free mass, FFM; and fat mass, FM). Analyses included agreement tests (kappa, Bowker’s test), regression models, and non-parametric tests. Results – In the first study, overall concurrence between Fenton and INTERGROWTH charts at birth was reasonable; however, substantial discrepancies were observed among small-for-gestational-age (SGA) newborns, particularly those between 28 and 32 weeks of gestation. In these cases, the Fenton chart tended to overestimate Z-scores, potentially influencing therapeutic decisions. In the second study, despite the strong association among charts (R² ranging from 0.76 to 0.86), malnutrition diagnoses varied considerably (kappa values between 0.29 and 0.56). INTERGROWTH identified the fewest cases of malnutrition. Fenton chart classified a higher proportion of infants with low FFM as malnourished (46.1% vs. 16.4%), whereas INTERGROWTH underestimated malnutrition in cases of excess FM. The Olsen chart showed no significant association with body composition parameters. Conclusion – Growth charts differ substantially in identifying the nutritional status of preterm infants at birth and during hospitalization. More refined concordance analyses revealed that overlap varies according to the value of the evaluated indicator, being lower for lower Z-scores, and disproportionately affecting more immature SGA infants. The Fenton chart identified fewer cases of malnutrition at birth but more during follow-up (many associated with fat-free mass deficits) while the INTERGROWTH chart exhibited the opposite pattern. The choice of growth chart should be contextualized and, whenever possible, complemented by objective body composition measures to reinforce more accurate clinical decision-making.