Forced Oscillation Technique vs Spirometry for Identifying Poorly Controlled Asthma

Spirometry test
Spirometry test
Persistent bronchodilator response measured by forced oscillation technique identified more cases of poor asthma control than did spirometry.

Persistent bronchodilator response (BDR) measured by forced oscillation technique (FOT) identified more cases of poor asthma control than did spirometry, according to study results published in CHEST.

Australian investigators reviewed data from 52 adult patients with asthma who attended a tertiary airways clinic from 2015 to 2017. Participants were included in this review if all bronchodilator medications were withheld for ≥8 hours before testing and if assessments were completed in a single visit. Lung function tests were performed before and ≥10 minutes after bronchodilator administration.

Spirometry and FOT were performed immediately before and after bronchodilator, with FOT performed before spirometry at both time points. The examined parameters of FOT included respiratory system resistance (R5) and reactance (X5) at 5 Hz, as well as area under the reactance curve (AX). In addition, the Asthma Control Test was used to assess asthma-related symptoms.

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The use of FOT more frequently identified BDR than spirometry (54% vs 27% of participants, respectively). There were significant associations between BDR on spirometry with BDR, as assessed by X5 (χ2=11.6; P =.001) and AX (χ2=8.8; P =.003). Asthma control correlated with BDR assessment by X5 (rs=-0.36; P <.01) and AX (rs= 0.34; P =.01). Using X5 and AX to measure BDR identified an additional 10 participants with poor asthma control vs spirometry.

For the detection of poor asthma control, BDR assessed by AX featured the greatest sensitivity (22 participants; 69% sensitivity; 75% specificity), followed by X5 (18 participants; 56% sensitivity; 85% specificity) and spirometry (13 participants; 41% sensitivity; 95% specificity).

Limitations of the study included the small sample size as well as the inclusion of patients with more impaired lung function and more difficult to control asthma than patients typically treated in the community setting.

Findings likely “…support the use of BDR assessed by FOT to complement spirometry in the clinical management of asthma,” the researchers reported.

Disclosure: Several study authors declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.


Cottee AM, Seccombe LM, Thamrin C, King GG, Peters MJ, Farah CS. Bronchodilator response assessed using the forced oscillation technique identifies poor asthma control with greater sensitivity than spirometry [published online January 23, 2020]. CHEST. doi:10.1016/j.chest.2019.12.035