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Revisiting the Definition of Bronchopulmonary Dysplasia: Effect of Changing Panoply of Respiratory Support for Preterm Neonates

Importance Several definitions of bronchopulmonary dysplasia are clinically used; however, their validity remains uncertain considering ongoing changes in the panoply of respiratory support treatment strategies used within neonatal units. Objective To identify the optimal definition of bronchopulmonary dysplasia that best predicts respiratory and neurodevelopmental outcomes in preterm infants. Design, Setting, and Participants Retrospective cohort study at tertiary neonatal intensive care units. Preterm infants born at less than 29 weeks’ gestation between 2010 and 2011 who were admitted to neonatal intensive care units participating in the Canadian Neonatal Network and completed follow-up assessments in a Canadian Neonatal Follow-Up Network clinic at 18 to 21 months. Exposures Various traditional bronchopulmonary dysplasia criteria based on respiratory status at different postmenstrual ages. Main Outcomes and Measures Serious respiratory morbidity, neurosensory impairment at 18 to 21 months of age, and a composite outcome of respiratory or neurosensory morbidity or death after discharge. Adjusted odds ratios (AORs) and 95% CIs were calculated. Results Of 1914 eligible survivors, 1503 were assessed (mean gestational age was 26.3 weeks; 68% were white, 9% were black, and 23% were other race/ethnicity), 88 had serious respiratory morbidity, 257 infants had neurosensory impairment, and 12 infants died after discharge. Definitions using oxygen requirement alone as the criterion at various postmenstrual ages were less predictive compared with those using the criterion of oxygen/respiratory support (RS) (receiving supplemental oxygen and/or positive-pressure RS); among those, oxygen/RS at 36 weeks had the highest AOR and area under the curve (AUC) for all outcomes. Further analyses of oxygen/RS at each week between 34 and 44 weeks’ postmenstrual age indicated that the predictive ability for serious respiratory morbidity increased from 34 weeks (AOR, 1.8; 95% CI, 0.9-3.4, AUC, 0.721) to 40 weeks (AOR, 6.1; 95% CI, 3.4-11.0; AUC, 0.799). For serious neurosensory impairment, the AOR and AUC at 40 weeks’ PMA (AOR, 1.5, 95% CI, 1.0-2.1; AUC, 0.740) were only marginally below their peak values at 37 weeks’ PMA (AOR, 1.8; 95% CI, 1.3-2.6; AUC, 0.743). Conclusions and Relevance Defining bronchopulmonary dysplasia by the use of oxygen alone is inadequate because oxygen/RS is a better indicator of chronic respiratory insufficiency. In particular, oxygen/RS at 40 weeks’ PMA was identified as the best predictor for serious respiratory morbidity, while it also displayed a good ability to predict neurosensory morbidity at 18 to 21 months.