Severity of Bronchopulmonary Dysplasia Using a Contemporary Canadian Definition and Early Childhood Outcomes: A Population-Based Cohort Study

OBJECTIVES: To determine the association between a bronchopulmonary dysplasia (BPD) definition used by the Canadian Neonatal Network (CNN) for grading and childhood outcomes and to compare that with the Neonatal Research Network (NRN) 2019 BPD definition. STUDY DESIGN: We conducted a population-level, retrospective cohort study of neonates born at <29 weeks' gestational age and admitted to Canadian tertiary neonatal intensive care units within the CNN for whom follow-up data were available. Eligible neonates admitted between 2016 and 2020 were categorized as having no, mild, moderate, or severe BPD. The primary outcomes were significant respiratory morbidity during early childhood and significant neurodevelopmental impairment (sNDI), both with and without mortality, by age 18-24 months. RESULTS: Of 5511 eligible neonates, 3816 were included in this study after excluding 1695 without follow-up data. The CNN BPD definition was associated with a significant increase in respiratory morbidity (±mortality) for both moderate and severe BPD (vs no BPD), and the definition was associated with an increase in sNDI (±mortality) for severe BPD (vs no BPD) only. Using the NRN 2019 BPD definition, significant respiratory morbidity (±mortality) was associated with all grades of BPD (vs no BPD), and an increase in sNDI (±mortality) was associated only with grade 3 BPD (vs no BPD). CONCLUSIONS: There is a graded association between BPD and long-term childhood outcomes. With use of the CNN definition of BPD, both moderate and severe BPD were associated with respiratory morbidity, whereas only severe BPD was associated with sNDI.