Clinical Significance of Positive Bronchodilator Response

Definition and Prevalence

A positive bronchodilator response is defined as an increase in lung function of ≥12% and ≥200 mL from baseline after bronchodilator administration, according to the European Respiratory Society guidelines 3, 4

In smokers with normal lung function, those with a greater and more consistent bronchodilator response are more likely to progress to chronic obstructive pulmonary disease (COPD), as found in the SPIROMICS study 1, 2
The SPIROMICS study also found that bronchodilator response in smokers with normal lung function was associated with lower pre-bronchodilator lung function, greater gas trapping on imaging scans, and higher risk of progression to COPD diagnosis over time 1, 2

Historically, bronchodilator response was used to differentiate asthma from COPD, but this distinction is now recognized as having poor discriminative properties, as many COPD patients also demonstrate significant flow and volume responses, according to the European Respiratory Society guidelines 2

The lack of a bronchodilator response in laboratory testing does not preclude a clinical response to bronchodilator therapy, and responses below significant thresholds may still be associated with symptom improvement and better patient performance, as found in studies published in the European Respiratory Journal 5

For patients with normal lung function but strong clinical suspicion of COPD, additional testing may be warranted, including assessment of lung function ratios, which may detect more peripheral airflow obstruction, as recommended by the European Respiratory Society guidelines 1, 2
In patients with normal lung function but persistent respiratory symptoms, consider changes in lung volumes which may improve after bronchodilation despite minimal changes in lung function ratios, as found in studies published in the European Respiratory Journal 5

Bronchodilator response testing lacks standardization regarding which bronchodilator to use, appropriate dosing, and criteria for positive response, according to the European Respiratory Society guidelines 2
The magnitude of bronchodilator response may be more clinically relevant than simply categorizing as "positive" or "negative", as found in studies published in the European Respiratory Journal 1, 2