Predictors of Bronchodilator Response on Oscillometry and Spirometry in School‐Age Children With Bronchopulmonary Dysplasia

ABSTRACT This study aimed to identify predictors of bronchodilator response (BDR) on oscillometry and spirometry for school‐age children with bronchopulmonary dysplasia (BPD). We hypothesized that clinical and neonatal characteristics influence BDR. Participants aged 6–12 years enrolled in the Air Quality, Environment and Respiratory Outcomes in BPD (AERO‐BPD) observational study performed pre‐ and post‐bronchodilator oscillometry and spirometry. Measures included forced expiratory volume in 1 s (FEV 1 ), forced vital capacity (FVC), FEV 1 /FVC, airway resistance at 5 Hertz (Hz, R 5 ), resistance between 5 Hz and 19 Hz (R 5‐19 ), resonant frequency (F res ), reactance at 5 Hz (X 5 ), and area under the curve between F res and X 5 (AX). Spirometric BDR was defined as pre‐ minus post‐bronchodilator measures relative to predicted. Oscillometry BDR was defined by pre‐ minus post‐bronchodilator relative to pre‐bronchodilator. Positive BDR response was defined as change in (Δ)AX < −80%, ΔR 5 < −40%, ΔX 5 > +50%, ΔFEV 1 > +10% and ΔFVC > +10%. Logistic regression tested predictors of BDR. Among 119 participants who performed paired pre‐ and post‐bronchodilator oscillometry and spirometry, median pre‐bronchodilator z‐scores of all measures were normal (within +/−1.64). More participants had BDR on spirometry than oscillometry (33% per FEV 1 , 10% per FVC, 9% per X 5 , 7% per R 5 , and 3% per AX). Inter‐device measures overall correlated weakly. Lower pre‐bronchodilator FEV 1 was strongly associated with increased odds of BDR on both devices, while no neonatal variables showed evidence of associations. In school‐aged children with BPD, approximately one‐third exhibited BDR. Spirometry showed greater rates of BDR than oscillometry. Lower pre‐bronchodilator FEV 1 was linked with higher likelihood of BDR. Neonatal history does not predict BDR.