Published online: April 27, 2018
An eosinophil is a type of white blood cell that can be elevated with allergic conditions, including asthma. Previous studies have suggested that patients with chronic obstructive pulmonary disease (COPD) with increased sputum eosinophils have frequent COPD exacerbations. However, it is not clear whether blood eosinophil counts are associated with frequent exacerbations. In a study recently published in The Journal of Allergy & Clinical Immunology (JACI), Yun and colleagues examined the relationship between blood eosinophil counts and exacerbation frequency. They used data collected from two large COPD studies, COPDGene with 1,553 patients and ECLIPSE with 1,895 patients.
The researchers analyzed the association between blood eosinophil counts and percentages with exacerbation frequency. In the COPDGene study, they found that an eosinophil count equal to or greater than 300 cells per microliter was significantly associated with exacerbation frequency. This level was examined in the ECLIPSE study, and found to be a significant predictor for future exacerbations up to three years. Twenty percent of COPD patients in both studies had eosinophil counts above this level. Upon further analysis, the authors found that in patients with a history of frequent exacerbations, elevated eosinophil counts were associated with a further increase in exacerbations compared to those without elevated eosinophils.
These results suggest that blood eosinophil measurement could be useful for risk stratifying patients with frequent exacerbations in COPD.
The Journal of Allergy and Clinical Immunology (JACI) is an official scientific journal of the AAAAI, and is the most-cited journal in the field of allergy and clinical immunology.