An alternative method for measuring lung function, oscillometry, is better at identifying patients with poorly controlled asthma when compared to spirometry, according to NSW researchers
Measurement of bronchodilator response (BDR) with the forced oscillation technique (FOT) is feasible in patients with asthma and BDR is associated worse asthma control, according to a study in 52 patients with asthma led by Dr Alice Cottee of the Department of Respiratory Medicine, Concord Repatriation General Hospital.
In the study, FOT was performed during tidal breathing with a commercial device (Tremoflo C-100) immediately prior to spirometry, both before and after bronchodilator.
Overall, BDR was identified more frequently by FOT than spirometry (54% vs 27% of subjects).
BDR measured by reactance parameters also identified more subjects with poor asthma control than spirometry (69% vs 41%). BDR assessed by area under the reactance curve (AX) had the greatest sensitivity to detect poor asthma control (22 subjects; 69% sensitivity, specificity 75%), whereas spirometry identified it in fewer people but with fewer false positives (13 subjects, 41% sensitivity, specificity 95%). In addition, BDR was associated with spirometric BDR and correlated with asthma control.
Writing in Chest, the researchers said the presence of a bronchodilator response (BDR) is useful in establishing the diagnosis of asthma, and findings from previous studies had shown that a persistent BDR despite antiinflammatory treatment was associated with greater inhaled corticosteroid doses, lower FEV1, worse asthma control, higher exacerbation rates and increased mortality
This suggested that ongoing BDR may be an important but under-recognized ‘treatable trait’ target in asthma, they said.