Growth phenotypes of very low birth weight newborns for the prediction of neonatal outcomes of a Brazilian cohort

Abstract

Introduction: Preterm birth is the main cause of perinatal mortality and is a consequence of inadequate intrauterine conditions. 

Objective: To assess the predictive value of selected growth phenotypes for neonatal morbidity and mortality in very low birth weight (VLBW) infants and to compare them with INTERGROWTH-21st (IG21). 

Method: Retrospective analysis of data from the Brazilian Neonatal Research Network (BNRN) database for VLBW at 20 public tertiary-care university hospitals. Outcome: the composite neonatal morbidity and mortality (CNMM) consisted of in-hospital death, oxygen use at 36 weeks, intraventricular hemorrhage grade 3 or 4, and Bell stage 2 or 3 necrotizing enterocolitis. Selected growth phenotypes: small-for-gestational-age (SGA) defined as being below the 3rd (SGA3) or 10th (SGA10) percentiles of BW, and large-for-gestational-age (LGA) as being above the 97th percentile of BW. Stunting as being below the 3rd percentile of the length and wasting as being below the 3rd percentile of BMI. Single and multiple log-binomial regression models were fitted to estimate the relative risks with respective 95% confidence intervals of CNMM, comparing them to IG21. 

Results: 4,072 infants were included. The adjusted relative risks of CNMM associated with selected growth phenotypes were (BNRN/IG21): 1.45 (0.92-2.31)/1.60 (1.27-2.02) for SGA; 0.90 (0.55-1.47)/1.05 (0.55-1.99) for LGA; 1.65 (1.08-2.51)/1.58 (1.28-1.96) for stunting; and 1.48 (1.02-2.17) for wasting. Agreement between the two references was variable. The growth phenotypes had good specificity (> 95%) and positive predictive value (70-90%), with poor sensitivity and low negative predictive value. 

Conclusion: The BNRN phenotypes at birth differed markedly from the IG21 standard and showed poor accuracy in predicting adverse neonatal outcomes.