A Large Subgroup Of Mild-to-Moderate Asthma Is Persistently Non-Eosinophilic

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Academic Journal
Main Category: Respiratory / Asthma
Article Date: 11 Jan 2012 - 9:00 PST

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An investigation in the American Thoracic Society's American Journal of Respiratory and Critical Care Medicine reveals that a great number of patients with mild to moderate asthma suffer from persistently non-eosinophilic disease, which may stay unresponsive to currently available anti-inflammatory treatments.

995 individuals with asthma were enrolled in 9 human trials carried out by the NHLBI's Asthma Clinical Research Network. In the cross-sectional investigation the researchers discovered that sputum eosinophilia (≥2% eosinophilia) was detected in 36% of asthma patients who don't use an inhaled corticosteroid (ICS) and 17% of asthmatics who use an ICS. Sputum eosinophilia was found in 15% of patients who did not achieve good asthma control, in comparison to 26% of asthmatics who achieved good asthma control.

• 22% of asthmatics not taking ICS who had repeated induced sputum samples had persistent eosinophilia
• 47% had persistently non-eosinophilic (no eosinophilia on every occasion)
• 31% of participants had eosinophilia on at least one occasion (intermittent eosinophilia)

In participants with eosinophilia asthma, 2 weeks of therapy with a combination of anti-inflammatory medications resulted in considerable improvements in airflow obstruction. However, these improvements were not observed in participants with persistently non-eosinophilic asthma, although in participants with eosinophilia and non-eosinophilic asthma, bronchodilator responses to albuterol were comparable.

John Fahy, MD, Msc, professor of medicine and director of the Cardiovascular Research Institute/University of California, San Francisco Airway Clinical Research Center, explained:

"Prevalence estimates for non-eosinophilic asthma in earlier studies were based on single sputum samples. Here we show for the first time that sputum eosinophilia is persistently absent in a large percentage of patients with mild/moderate asthma when sputum is analyzed repeatedly over time."

According to the team patients with persistently non-eosinophilic asthma who responded poorly to intense combined treatment have a unique disease phenotype and new treatments need to be developed. In addition, the researchers found that treatment responses in patients with persistent eosinophilia and intermittent eosinophilia were similar.

Written by Grace Rattue
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