According to an article published online in the American Thoracic Society’s American Journal of Respiratory and Critical Care Medicine, only about a third of asthma patients not using an inhaled corticosteroid (ICS) and 17% of those using ICS had eosinophils in their sputum, an indicator of inflammation that suggests they would likely respond to ICS treatment. The remaining 62% of the patients, therefore, likely have a disease phenotype that would not respond to ICS, according to the authors.
The article, titled “A Large Subgroup of Mild-to-Moderate Asthma is Non-eosinophilic,” describes a study conducted by the Asthma Clinical Research Network of the National Heart Lung and Blood Institute (NHLBI) involving almost 1,000 patients in nine clinical trials. The researchers conclude that “approximately half of patients with mild-to-moderate asthma have persistently non-eosinophilic disease.”
After treating 645 of the patients with ICS for two weeks, the researchers found that those with eosinophils in their sputum experienced significant improvement in lung function while patients with persistently non-eosinophilic asthma did not. Both groups experienced similar responses to a bronchodilator.
According to John Fahy, Professor of Medicine and Director of the Cardiovascular Research Institute/University of California San Francisco Airway Clinical Research Center, “A large subgroup of patients with mild-to-moderate asthma do not have the usual eosinophilic subtype that is responsive to steroid treatment. In addition to the implications for the care of these patients, our results have important implications for future asthma research. In clinical studies, the eosinophil phenotype of patients should be characterized to better understand treatment responses and disease mechanisms. In addition, appropriate in vitro and animal models for the study of the mechanisms of non-eosinophilic airway disease need to be developed.”
Read the ATS press release.
Read the article.
