A recent study entitled “Eosinophilic inflammation in COPD: prevalence and clinical characteristics” reports that patients with chronic obstructive pulmonary disease can have persistent eosinophilia, and that this feature is associated with better COPD outcomes. The study was published in the European Respiratory Journal.

Chronic obstructive pulmonary disease (COPD) is characterized by chronically poor airflow and frequently associated with emphysema (loss of alveolar surface area) and bronchitis (a condition where inflammation of the mucous membranes of the bronchi occurs). Disease severity in COPD escalates over time and is ranked as the fourth leading cause of mortality worldwide. In 2011, 13 million American adults were estimated to suffer from COPD, according to The American Lung Association.

While one of the characteristics associated with asthma is eosinophilic inflammation — an accumulation of eosinophils, a type of white blood cell of the immune system in the airways — recent studies suggest that eosinophilic inflammation occurs in some COPD patients as well. The study was part of ECLIPSE (Evaluation of COPD Longitudinally to Identify Predictive Surrogate End-points), and the authors determined eosinophil was found in the blood of 1,483 participants with COPD between 40 to 75 years old.

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The researchers found that 37.4% of these patients exhibited high levels of eosinophils (2% or higher). When they compared these patients’ respiratory capacity against patients with eosinophil levels below 2% or with intermittent eosinophilia, they observed high eosinophil counts are associated with improved lung function, denoted by higher forced expiratory volume in 1 second and lower airflow obstruction and dyspnea. Additionally, the authors observed emphysema progression was inversely correlated with eosinophil levels, with patients’ levels below 2% exhibiting far more extensive emphysema progression.

In light of these results, the authors concluded that “the finding of persistently elevated eosinophils may be a simple predictor of more lung eosinophils, and hence increased likelihood of corticosteroid responsiveness.”