Introduction: During NICU hospitalization, children born preterm with bronchopulmonary dysplasia (BPD) are frequently prescribed diuretics for treatment of respiratory symptoms. However, less is known about diuretic use and weaning in the outpatient setting. This study sought to characterize clinical features associated with outpatient diuretic use, and timing of diuretic weaning in children with BPD. Methods: Data was obtained by chart review from registry 1224 participants born < 32 weeks gestation, discharged between 2008-2023 and recruited from outpatient BPD clinics at Johns Hopkins Children’s Center and the Children’s Hospital of Philadelphia (97.4% diagnosed with BPD). Data was analyzed using Chi-square tests, t-tests, and ANOVA tests. Results: Children with BPD prescribed diuretics as outpatients (n=737), were more likely to have lower birth weights, earlier gestational age, and severe BPD compared to those not on diuretics (n=487). Of those prescribed diuretics, most children were on a thiazide alone (46.4%) or a thiazide and a potassium sparing agent (44.8%) with a minority on loop diuretics alone (3.3%) or loop diuretic combinations (4.7%). Most children weaned off diuretics by two years of age. Public insurance, earlier gestational age, technology dependence and loop diuretics were associated with slower diuretic weaning. Conclusion: Outpatient diuretic use is common in BPD with > 75% of children being weaned by two years of age. No difference was found in weaning of home oxygen between children on one versus no diuretic. Thiazides were most commonly prescribed with slower outpatient diuretic weaning associated with public insurance, technology dependence and loop diuretic use.

Objectives: To quantify the association of ambient air pollution (particulate matter, PM 2.5) exposure with medically attended acute respiratory illness among infants with bronchopulmonary dysplasia (BPD). Study Design: Single center, retrospective cohort study of preterm infants with BPD in Metropolitan Philadelphia. Multivariable logistic regression quantified associations of annual mean PM 2.5 exposure (per μg/m 3) at the census block group level with medically attended acute respiratory illness, defined as emergency department (ED) visits or hospital readmissions within a year after first hospital discharge adjusting for age at neonatal intensive care unit (NICU) discharge, year, sex, race, insurance, BPD severity, and census tract deprivation. As a secondary analysis, we examined whether BPD severity modified the associations. Results: Of the 378 infants included in the analysis, 189 were non-Hispanic Black and 235 were publicly insured. Census block PM 2.5 level was not significantly associated with medically attended acute respiratory illnesses, ED visits, or hospital readmissions in the full study cohort. We observed significant effect modification by BPD grade; each 1 µg/m 3 higher annual PM 2.5 exposure was medically attended acute respiratory illness (aOR 1.65, 95% CI: 1.06-2.63) among infants with grade 1 BPD but not among infants with grade 3 BPD (aOR 0.83, 95% CI: 0.47-1.48) (interaction p=0.024). Conclusions: Cumulative PM 2.5 exposure in the year after NICU discharge was not significantly associated with medically attended acute respiratory illness among infants with BPD. However, infants with grade 1 BPD had significantly higher odds with higher exposures. If replicated, these findings could inform anticipatory guidance for families of these infants to avoid outdoor activities during high pollution days after NICU discharge.