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Table. Spirometry findings in asthma, COPD and asthma–COPD overlap


Consistent with

Asthma COPD Asthma–COPD overlap

Normal FEV1 /FVC before of after bronchodilator

  Yes   No   No *

Abnormal lung function

(post-bronchodilator reduced FEV1/FVC and FEV1 < lower limit of normal)

  Yes #   Yes   Yes

Airflow limitation with greater bronchodilator reversibility than in healthy population

(post-bronchodilator FEV1 increase ≥ 12% and 200mL from baseline)

  Yes   Yes   Yes

Marked bronchodilator reversibility

(FEV1 increase ≥ 12% and 400mL from baseline)

  Yes   Possible but unusual   Possible §

FEV1/FVC: ratio of forced expiratory volume in one second (FEV1) to forced vital capacity (FVC), either before or after bronchodilator

* Normal FEV1/FVC is not consistent with COPD unless there is other evidence of chronic non-reversible expiratory airflow limitation.

# This finding is consistent with asthma that is poorly controlled or measured during a flare-up, or can be seen in some patients with longstanding asthma.

‡ The greater the variation, and the more times variation is seen, the more likely the diagnosis of asthma. However, some patients with longstanding asthma may develop persistent airflow limitation.

† Marked reversibility strongly favours asthma and is generally inconsistent with COPD, but does not rule out asthma–COPD overlap.

§ This finding may be seen in patients with asthma–COPD overlap, or occasionally in COPD, especially when FEV1 is low.


Global Initiative for Asthma, Global Initiative for Obstructive Lung Disease. Diagnosis and initial treatment of asthma, COPD and asthma-COPD overlap. Updated April 2017. Global Initiative for Asthma and Global Initiative for Obstructive Lung Disease; 2017. Available from:

Woodruff P, van den Berge M, Boucher R et al. ATS-NHLBI Asthma COPD Overlap (ACO) Workshop Report. Am J Respir Crit Care Med 2017; 196:375-381. Available from:


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