Discussion
The burden of respiratory morbidities in children with BPD can be
lifelong 13 and identifying those at highest risk for
long-term respiratory morbidities, is challenging. Children with BPD who
require supplemental oxygen at initial hospital discharge have varying
degrees of cardiopulmonary involvement and are likely at higher risk for
chronic respiratory symptoms during the pre-school years when compared
to children discharged off supplemental oxygen.14Identifying factors that predict outpatient acute care usage, chronic
respiratory symptoms and timing to oxygen liberation could help modify
respiratory morbidities in these children . This study focused on
children with BPD discharged to home on supplemental oxygen to address
these issues. Not unexpectantly, children discharged on higher levels of
supplemental oxygen were more likely to have severe BPD and to carry the
diagnosis of pulmonary hypertension. Additionally, those who required
higher levels of supplemental oxygen at initial hospital discharge were
more likely to have lower birthweight percentiles and to be older at
initial hospital discharge. However, children discharged on higher
levels of supplemental oxygen did not have a higher likelihood of acute
care usage, chronic respiratory symptoms or need for respiratory
medications during acute illnesses when compared to those discharged on
lower levels of supplemental oxygen. The likelihood of weaning
supplemental oxygen, in a given month, was significantly lower in
children with gastrostomy tubes, children prescribed inhaled
corticosteroids and in those who lived in homes with lower estimated
incomes. Findings from this study suggest that although severity of BPD
influences level of supplemental oxygen at initial hospital discharge,
other factors after hospital discharge influence weaning of supplemental
oxygen and respiratory morbidities, including socioeconomic status (SES)
and ICS use, which could be modifiable factors.
In this study, several risk factors were associated with delayed weaning
of supplemental oxygen. In particular, we found that weaning oxygen, per
given month was less likely in children with lower estimated household
incomes. This finding suggest that socioeconomic status can be a factor
in liberating a child from supplemental oxygen in the outpatient
setting. This finding raises the question of whether children with lower
SES, have more difficulties in accessing care, once they are in the
outpatient setting. However, a recent study did not support
this.15 Additional studies will be needed to determine
if other health disparities or perceptions due to SES, influence
variations in oxygen weaning strategies in children with BPD. We also
found that higher use of ICS was associated with delayed weaning of
supplemental oxygen. It is possible that ICS was used as an additive
therapy in those who were more difficult to wean from supplemental
oxygen, which may account for delayed weaning of supplemental oxygen.
Other reasons may also affect weaning in the outpatient setting. Wong
et. al., studied infants with moderate or severe BPD discharged on
varying amounts of supplemental oxygen. They found that shorter NICU
stays were associated with quicker oxygen weans at 9 and 12 months with
no correlation to birthweight or gestational age.16Our findings indicate that factors after initial hospital discharge can
influence weaning of supplemental oxygen in children with BPD.
In this study, no differences in acute care usage or respiratory
symptoms were found between any of the oxygen groups in children with
BPD. Higher levels of supplemental oxygen at discharge were not
associated with increased rates of emergency room visits,
hospitalizations, systemic steroid use, or antibiotic use for
respiratory conditions. There were also no differences in chronic
respiratory symptoms or rescue medication use between the oxygen groups.
It is possible that supplemental oxygen use in the outpatient setting
lowers hospitalizations in BPD children by mitigating hypoxemia that can
occur during acute respiratory illnesses, regardless of amount given.
Greenough et. al., reported that children with BPD between the ages of 2
to 4 years who required supplemental oxygen did not have increased
hospital admissions, compared to those on room air. 9However, their study did see an increase in wheezing and use of
inhalers. Lodha et. al., 10 also examined respiratory
outcomes at 3 years of age in children without BPD, with BPD, and with
BPD on supplemental oxygen. They reported that children with BPD on
supplemental oxygen did not have higher rates of hospitalization or
antibiotic use compared to the other groups. Unlike our study however,
Lodha et. al., did not stratify by amount of supplemental oxygen use.
Other studies however, have shown higher rates of rehospitalization for
respiratory issues in infants with BPD requiring oxygen supplementation
at home.8,16 Our study suggest that being on any level
of supplemental oxygen at initial discharge, could provide a buffer to
support adequate oxygen levels during periods of illness, lessening the
likelihood of hospitalization in children with more severe BPD.
A limitation of this study is the retrospective nature of the study
design. Furthermore, this study included patients from two centers, in
which the demographics of these cohorts predominately represent an urban
population, which may not be generalizable to other patient populations,
particularly those in rural areas. Additionally, both centers in this
study have outpatient BPD clinics which may account for higher comfort
in discharging children with BPD on higher levels of oxygen in the
outpatient setting. Nevertheless, our study results suggest that the use
of supplemental oxygen can help to mitigate differences in BPD severity
with regard to acute care usage and reported respiratory symptoms in
children with BPD in the outpatient setting.
In summary, among BPD children on supplemental oxygen in the outpatient
setting, the level of oxygen supplementation at initial hospital
discharge was not shown to correlate with acute care usage or
respiratory symptoms. Weaning of supplemental O2 however
was significantly associated with household income and ICS use,
indicating that these factors can influence timing of oxygen weaning by
healthcare providers in the outpatient setting.
Table 1: Demographic and Clinical Characteristics by Oxygen
Amount at Initial Hospital Discharge