Methods
A retrospective chart review was performed on subjects (n=417) recruited
from outpatient BPD clinics at the Children’s Hospital of Philadelphia
and Johns Hopkins Children’s Center between 2008-2021. All subjects were
born at less than 37 weeks-gestation and were diagnosed with BPD by NIH
consensus definition,11 and were on home supplemental
oxygen via nasal cannula; patients with tracheostomies or home
ventilators were excluded. This study was approved by Johns Hopkins
Institutional Review Board (Protocol #NA_00051884) and the Children’s
Hospital of Pediatrics Institutional Review Board (IRB# 20-017614) and
all caregivers were consented.
Children using supplemental O2 at initial hospital
discharge were divided into four groups. Those who required ≤1/8 lpm of
O2 (group 1), those who required >1/8 lpm
of oxygen but <1/2 lpm of O2 (group 2), those
who required ≥1/2 lpm O2 but <1 lpm
O2 of oxygen (group 3), and those who required ≥1 lpm
O2 of oxygen (group 4). Demographic data and clinical
characteristics were collected by chart review. Birthweight percentile
was corrected by gestational age.12 Race/ethnicity was
obtained through caregiver report. Median household income was estimated
using residential zip codes based on U.S. Census data.
Acute care usage and chronic respiratory symptom data was obtained via
caregiver-completed questionnaires at outpatient visits when subjects
were between 0 and 3 years of age.
Statistics: Chi square and ANOVA tests were performed to
compare demographic data and clinical characteristics between oxygen
groups (Table 1). Cox regressions adjusted for inter-site variation were
performed to identify factors associated with earlier or later
liberation from supplemental oxygen (Table 2). Associations between
amount of oxygen at initial hospital discharge and acute care
use/chronic respiratory symptoms were assessed for via logistic
regression models adjusted for inter-site variation, potential
demographic/clinical confounders, duration of oxygen use, number of
questionnaires, and age of questionnaire assessments (Table 3). Results
that were statistically significant had a P value less than or equal to
0.05. Stata IC 16 was used for data analysis.