2.1 Study Design
We performed a retrospective chart review of infants born with a body
weight less than 1000 g and admitted to National Cheng Kung University
Hospital from July 2014 to June 2020. We enrolled infants who received
PDA invasive management involving either surgical ligation or
transcatheter occlusion and were diagnosed with BPD at 36 weeks’
post-menstrual age. Infants with BPD severity already classified before
the procedure were excluded. According to the NICHD 2001 BPD diagnosis
criteria, BPD was considered as 28 cumulative days of supplemental
oxygen more than 21%. The severity of BPD was defined according to a
previously published definition (Supplementary Table 1).16 Based on the type of intervention, patients were
divided into a surgical ligation group (Group A) or a transcatheter
occlusion group (Group B). The study protocol was approved by the
Institutional Review Board (protocol code A-ER-109-137) of this
institution.