April 2024
Is bronchodilator responsiveness helpful in differentiating between different types of obstructive airway disease?

In a large cohort, it did not distinguish between asthma and chronic obstructive pulmonary disease.

We have been taught that patients with asthma have bronchodilator responsiveness, whereas patients with chronic obstructive pulmonary disease (COPD) have irreversible obstruction. Bronchodilator responsive­ness has recently been redefined as an increase of more than 10% in forced expiratory volume in one second (FEV1) or forced vital capacity (FVC) relative to the predicted value, at 10 to 15 minutes after administration of a quick­acting bronchodilator. Researchers examined the utility of evaluating bronchodilator responsiveness in an international cohort of patients with physician­diagnosed asthma or COPD.

Among 3500 adolescent and adult patients (age, 12 years or older), broncho­ dilator responsiveness was about 19% for asthma, 18% to 25% for COPD and 23% to 30% for asthma plus COPD. In general, greater bronchodilator responsiveness was associated with worse lung function and higher symptom burden, and a higher likelihood that a patient had asthma along with type 2 inflammation (i.e. eosino­philic or allergic). In patients who already were using inhaled corticosteroids (ICS), bronchodilator responsiveness was rarely present.

Comment: Spirometry is still invaluable, but the authors argue that a positive bronchodilator responsiveness test should not be a requirement for diagnosing asthma, as it cannot differentiate asthma from COPD. Rather, bronchodilator responsiveness should be considered a ‘treatable trait’ that can be used to predict severity and guide treatment, because it is a marker of uncontrolled asthma and responsiveness to ICS. Although a post­bronchodilator FEV1/FVC below 0.7 is still required to diagnose COPD, about a quarter of patients will have bronchodilator responsiveness. And although patients with bronchodilator responsiveness have more severe disease, the presence or absence of responsiveness to short-­acting bronchodilators in patients with COPD does not predict their response to long-­acting bronchodilators.

David J. Amrol, MD, Associate Professor of Clinical Internal Medicine, Director of the Division of Allergy and Immunology, University of South Carolina School of Medicine, Columbia, USA.

Beasley R, et al. Prevalence, diagnostic utility and associated characteristics of bronchodilator responsiveness. Am J Respir Crit Care Med 2024; 209: 390-401.

This summary is taken from the following Journal Watch titles: General Medicine, Ambulatory Medicine, Pediatrics and Adolescent Medicine, Hospital Medicine.

Am J Respir Crit Care Med