Survival In Very Preterm Infants: An International Comparison Of 10 National Neonatal Networks

Current literature demonstrates significant variation in the outcomes and survival rates of preterm infants in different health care settings and countries. The International Network for Evaluating Outcomes of Neonates (iNeo) is a nonprofit partnership consisting of 10 national and regional neonatal networks that seeks to study and improve outcomes of very preterm infants through comparison of care practices.This cohort study sought to compare gestational age (GA)-specific survival rates for very preterm infants in all neonatal networks collaborating through iNeo and to analyze variations in age at death among the very preterm population. The study cohort included infants who were born between 24 and 29 weeks' gestation, weighed less than 1500 g, and were admitted to participating neonatal units between 2007 and 2013. The primary outcome of this study was survival to discharge from the hospital, measured in 1-week GA increments, for infants admitted to neonatal care. Statistical analysis was done using standardized ratios. Survival within each network of iNeo was compared with a pooled estimate for survival from the total study population using multivariate logistic regression models with adjustment for GA, birth weight, multiple births, and sex. The total study cohort consisted of 88,327 infants with a survival to discharge rate of 87%(n = 77,172).The overall survival rate within networks differed from 78% to 93%, with the greatest difference in percentage of survival occurring at 24 weeks' gestation (49% difference, 35% vs 84%). Survival increased across the total study population and internetwork populations as GA increased. In addition, the difference between networks' survival rates decreased as GA increased (92% vs 98% at 29 weeks' gestation). Neonatal Research Network Japan had the highest standardized ratio for survival with 1.10 (99% confidence interval, 1.08-1.13), and the Spanish Neonatal Network (SEN1500) had the lowest with 0.88 (99% confidence interval, 0.85-0.90). A total of 11,155 infants did not survive to discharge, and the median age at death varied from 4 days (Finnish Medical Birth Registrar) to 13 days (Neonatal Research Network Japan). The median age at death across the total study population was 8 days.This large-scale multinational study demonstrated significantly increasing survival rates of very preterm infants born between 24 and 29 weeks' gestation. Although the cross-network survival rate difference decreased with increasing GA, the relative ranking of each network did not change. Further research is indicated into the specific practices and organization of perinatal services among the networks that account for these marked differences.