Association between bronchopulmonary dysplasia severity and its risk factors and long-term outcomes in three definitions: a historical cohort study.

Objective: To compare the association of the severity categories of the 2001-National Institutes of Health (NIH), the 2018-NIH and the 2019-Jensen bronchopulmonary dysplasia (BPD) definitions with neurodevelopmental and respiratory outcomes at 2 and 5 years' corrected age (CA), and several BPD risk factors.

Design: Single-centre historical cohort study with retrospective data collection.

Setting: Infants born between 2009 and 2015 at the Amsterdam University Medical Centers, location Amsterdam Medical Center.

Patients: Preterm infants born at gestational age (GA) <30 weeks and surviving up to 36 weeks' postmenstrual age.

Interventions: Perinatal characteristics, (social) demographics and comorbidities were collected from the electronic patient records.

Main outcome measures: The primary outcomes were neurodevelopmental impairment (NDI) or late death, and respiratory morbidity at 2 and 5 years' CA. Using logistic regression and Brier scores, we investigated if the ordinal grade severity is associated with incremental increase of adverse long-term outcomes.

Results: 584 preterm infants (median GA: 28.1 weeks) were included and classified according to the three BPD definitions. None of the definitions showed a clear ordinal incremental increase of risk for any of the outcomes with increasing severity classification. No significant differences were found between the three BPD definitions (Brier scores 0.169-0.230). Respiratory interventions, but not GA, birth weight or small for GA, showed an ordinal relationship with BPD severity in all three BPD definitions.

Conclusion: The severity classification of three BPD definitions showed low accuracy of the probability forecast on NDI or late death and respiratory morbidity at 2 and 5 years' CA, with no differences between the definitions.