Clinical characteristics by bronchodilator response status
In the preterm group, those with a BDR by either test were more likely to have abnormal baseline lung function (Table 4). Those with a spirometry BDR had the lowest pre-bronchodilator spirometry; this relationship was non-linear (R2=0.44, p<0.001. Supplementary Figure E1). Similarly, those with an oscillometry BDR had the worst pre-bronchodilator oscillometry (Table 4), Whilst a BDR was more likely in those with lower baseline lung function, spirometry was not reduced in the group with a BDR by oscillometry alone, relative to the group without a BDR (FEV1 z-score MD= -0.01, 95%CI -0.66 to 0.68, p>0.999). However, in the group that had a BDR by oscillometry but not spirometry, airway resistance was increased (Rrs5 z-score MD= 0.86, 95%CI 0.07 to 1.65, p=0.025) as was wheeze (33% vs 11%, p=0.010), compared to those without a BDR.
Baseline lung function (oscillometry and spirometry) was lowest in those with a BDR detected by both tests (e.g., FEV1 z-score MD= -2.14, 95%CI -2.89 to -1.39, p<0.001), compared to those without a BDR.