Predictors of severe bronchopulmonary dysplasia in extremely low birth weight infants: results of a retrospective cohort study

Abstract

Objective. To identify clinical, laboratory and echocardiographic characteristics of the first day of life associated with severe bronchopulmonary dysplasia in extremely low birth weight infants. Material and methods. A single-centre retrospective cohort study was conducted at the Perm Regional Perinatal Center in 2020–2024. Eighty-two infants with a birth weight below 1000 g (range 560–998 g) and a gestational age of 23–30 weeks were included. Within the first 24 hours of life all infants underwent echocardiography (patent ductus arteriosus diameter, LA/Ao ratio, retrograde diastolic flow, pulmonary artery pressure), neurosonography, chest radiography, and haematological and biochemical testing. BPD severity was graded at 36 weeks postmenstrual age according to Jensen et al. (2019). The outcome was grade III BPD. Continuous variables were compared with the Mann–Whitney test and categorical variables with Fisher exact test; the Benjamini–Hochberg procedure was applied to all 43 comparisons. Logistic regression was used to assess independent contributions. Results. The outcome was assessed in 80 of 82 infants; two died before 36 weeks postmenstrual age and were treated as a competing outcome. Grade III BPD occurred in 28 infants (35.0 %). Severe BPD was associated with lower gestational age (median 26 vs 27 weeks), lower birth weight (800 vs 935 g), lower 1-minute Apgar score (4 vs 5), lower total protein (33.0 vs 39.0 g/L), shorter body length (33 vs 35 cm) and maternal gestational diabetes (17.9 % vs 0 %); all six differences remained significant after correction for multiplicity. Early haemodynamic parameters were not associated with the outcome: ductal diameter (p = 0.173), retrograde diastolic flow (p = 0.797), LA/Ao below 1.4 (p = 0.188), pulmonary artery pressure (p = 0.212), anterior cerebral artery resistance index (p = 0.462). In the multivariable model gestational age (OR 0.42; 95 % CI 0.25–0.71) and 1-minute Apgar score (OR 0.56; 95 % CI 0.33–0.95) remained independent predictors; the area under the ROC curve was 0.834, and 0.825 after optimism correction. Conclusions. The severity of bronchopulmonary dysplasia in extremely low birth weight infants is determined by immaturity and the condition at birth, whereas first-day cardiovascular adaptation parameters, including ductal diameter, carry no independent prognostic value.