A significant response to bronchodilator treatment in patients with bronchiectasis indicates worse lung function, according to new research. Scientists also noted that the risk for exacerbations tended to be lower in patients responding to bronchodilators.

Physicians often test the responsiveness to bronchodilator therapy when assessing bronchiectasis patients to give them a measure of the flexibility of the bronchi. However, few studies have explored the links between the response to bronchodilators and disease characteristics or prognosis.

Scientists at the First Affiliated Hospital of Guangzhou Medical University in China recruited 129 patients with stable bronchiectasis to assess how a bronchodilator response correlated with measurements such as inflammation, the presence of bacteria and factors linked to collagen breakdown, and findings on high-resolution computed tomography (HRCT) scans of the chest.

The study, “Bronchodilator response in adults with bronchiectasis: correlation with clinical parameters and prognostic implications,“ published in the Journal of Thoracic Disease, showed that 8.5 percent of the patients had a significant response to bronchodilators, defined as an improvement in forced expiratory volume (FEV1) by more than 12 percent and 200 ml — and these were the patients who had the worst lung function at the start of the study.

Further analysis showed that, in fact, spirometry values at study start predicted the change in FEV1 triggered by bronchodilator drugs.

Comparing the two groups, researchers found that patients who responded to bronchodilators were less likely to have a normal sputum bacterial flora and more likely to have Pseudomonas aeruginosa infection, compared to non-responders. They also tended to have higher disease severity scores, although the finding was not statistically significant.

A response to bronchodilators did not predict a more rapid decline in lung function, but was linked to a somewhat lower risk of exacerbation, which again was not significant. Such findings might be explained by the fact that higher rates of glucocorticoids are prescribed in this group, keeping a potential exacerbation at bay.

Given that only 11 patients responded to bronchodilators, the findings need to be verified in a larger group — a task that might clarify the seemingly contradictory findings of the study with a lower risk of exacerbations despite Pseudomonas infection and worse lung function.