Bronchopulmonary dysplasia (BPD) is a term coined in 1967 to describe the clinical, pathologic, and radiographic features of preterm infants that require prolonged mechanical ventilation and oxygen support. Preterm infants initially developed hyaline membrane disease and, despite the high mortality rate, survived, but with severe mucosal, alveolar, and vascular changes due to the prolonged exposure to high ventilator pressures and oxygen. As survival improved and new advances in neonatal care were introduced, infants developed a different BPD, sometimes described as a “new BPD,” which was characterized by an arrest in alveolar development, less fibrosis, and a more uniform inflammation.
BPD continues to be the most prevalent sequelae among survivors following preterm birth. Defining BPD, however, has been a topic of debate ever since the initial criteria was proposed. A new study from the University of Kentucky compares the Shennan definition versus the consensus definition of BPD from the National Institutes of Health (NIH) workshop, and analyzes specific risk factors associated with each definition. The resulting paper appears in Frontiers in Pediatrics. The authors are Dr. Enrique Gomez Pomar, UK College of Medicine; Dr. Vanessa A. Concina, UK College of Medicine; Dr. Aaron Samide, Johns Hopkins All Children’s Hospital; Dr. Philip Westgate, University of Kentucky College of Public Health, and Dr. Henrietta Bada, UK College of Medicine and UK College of Public Health.
The investigators conducted a retrospective analysis of records of 274 infants admitted to a level IV intensive care unit. The infants were classified as having BPD or no BPD by both definitions. Investigators analyzed differences in incidence and risk factors; the statistical methods used included descriptive statistics, comparative tests, and marginal logistic regression modeling.
The estimated difference in prevalence was 32 percent, with the prevalence of BPD 80 percent higher based on the NIH criteria. Infants with no BPD by the Shennan definition were breathing room air with or without positive or continuous pressure support and were most likely to be discharged home on oxygen. Gestational age, birth weight, and 1-min Apgar score predicted BPD by both definitions. Chorioamnionitis increased the risk of BPD by the Shennan definition, but was associated with lower risk by the NIH criteria. Intrauterine growth restriction (IUGR) was associated with BPD by the Shennan definition and with severe BPD by the NIH criteria.
The authors conclude that “[c]ompared to the Shennan’s definition, the NIH consensus identified 80 percent more infants with BPD, and is a better predictor of oxygen requirement at discharge. Until a new, better criteria is developed, the NIH consensus definition should be used across centers.”