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

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 (FEV₁), forced vital capacity (FVC), FEV₁/FVC, airway resistance at 5 Hertz (Hz, R₅), resistance between 5 Hz and 19 Hz (R_5-19), resonant frequency (F_res), reactance at 5 Hz (X₅), and area under the curve between F_res and X₅ (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%, ΔR₅ < -40%, ΔX₅ > +50%, ΔFEV₁ > +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 FEV₁, 10% per FVC, 9% per X₅, 7% per R₅, and 3% per AX). Inter-device measures overall correlated weakly. Lower pre-bronchodilator FEV₁ 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 FEV₁ was linked with higher likelihood of BDR. Neonatal history does not predict BDR.