| Validation of a new Japanese classification for predicting
severe bronchopulmonary dysplasia in preterm infants |
Masato Ito1 
, Shinya Hirano2
, Fumihiko Namba3
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1Department of Neonatology, Akita Red Cross Hospital, Akita, Japan
2Department of Neonatal Medicine, Osaka Women’s and Children’s Hospital, Izumi, Japan
3Department of Pediatrics, Saitama Medical Center, Saitama Medical University, Kawagoe, Japan |
Correspondence:
Masato Ito, Email: m-ito.th@akita-med.jrc.or.jp
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Received: 5 November 2025 • Revised: 11 December 2025 • Accepted: 16 December 2025 |
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| Abstract |
Background
Bronchopulmonary dysplasia (BPD) is the
most prevalent chronic lung disease in very preterm infants;
however, conventional classifications have limited ability to
predict severity before 36 weeks' postmenstrual age (PMA).
A new Japanese classification, based on small for gestational
age (SGA), bubbly/cystic chest radiographic findings, and
chorioamnionitis (CAM), was proposed to enable earlier
risk stratification. However, its validation in homogeneous
cohorts is warranted.
Purpose
This study aimed to examine the association
between this new Japanese classification and severe BPD
development at 36 weeks' PMA in a secondary analysis of
a randomized controlled trial (RCT).
Methods
A retrospective secondary analysis of a multicenter,
double-blind RCT of inhaled corticosteroids in 12
tertiary neonatal intensive care units in Japan (2006–2009)
was performed. Infants with a birth weight (BW)<1,000
g and requiring mechanical ventilation were enrolled.
Of those 211 infants, 194 survivors were analyzed. Severe
BPD was defined by National Institute of Child Health and
Human Development criteria as requiring supplemental
oxygen (fraction of inspired O2 >0.30) or positive pressure
ventilation at 36 weeks' PMA. Logistic regression analyses
were adjusted for gestational age, BW, sex, Apgar score,
maternal steroid use, respiratory distress syndrome, and
patent ductus arteriosus.
Results
Among the 194 infants, 25 were SGA, 45 had
bubbly/cystic findings, and 86 had CAM. Severe BPD occurred
in 80 infants. A multivariate analysis identified
SGA (adjusted odds ratio [aOR], 3.32; 95% confidence interval
[CI], 1.16–9.48; P=0.032) and bubbly/cystic findings (aOR,
10.88; 95% CI, 4.43–26.72; P<0.01) as independent risk factors.
Compared with type II (non-CAM, no bubbly/cystic findings),
type I (bubbly/cystic only: aOR, 6.21; 95% CI, 1.93–14.36)
and type III (CAM plus bubbly/cystic: aOR, 15.32; 95% CI,
2.48–46.32) were significantly associated with severe BPD.
Conclusion
The new Japanese classification demonstrated
that SGA and bubbly/cystic findings at day 28 independently
predicted severe BPD. Early stratification using
this classification may facilitate the early identification of
high-risk infants for targeted interventions. |
| Key Words:
Bronchopulmonary dysplasia, Very low birth
weight infant, Small for gestational age infant, Chorioamnionitis,
Thoracic radiography |
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