African–American patients with chronic obstructive pulmonary disease (COPD) are more likely to be affected by therapy-induced bronchoconstriction, a study suggests.

Beta2 agonist drugs are used for their bronchodilatory properties in COPD, yet a paradoxical bronchoconstrictive effect, resulting in respiratory distress, occurs in some people.

The first systematic study of responses to beta-2 agonists has identified paradoxical bronchoconstriction in 5% of nearly 10,000 patients with COPD. A paradoxical response was twice as common in African–American patients than in other racial groups, and was also associated with worse respiratory outcomes, including more severe dyspnoea, shorter six-minute walk distance and more frequent severe exacerbations.