Bronchodilator reversibility and eosinophilic biomarkers in chronic obstructive pulmonary disease patients

Chronic Obstructive Pulmonary Disease (COPD) is now one of the top three causes of death worldwide. Recently, increased focus has been on COPD patients displaying eosinophilic inflammation and asthma-like features of bronchial hyperreactivity and bronchodilator responsiveness. The objective of the study was to measure the proportion of chronic obstructive pulmonary disease patients with bronchodilator reversibility and to compare the eosinophilic biomarkers between the bronchodilator non-reversible and reversible groups.

This hospital-based cross-sectional study included COPD patients who visited the Pulmonary Medicine OPD at the All-India Institute of Medical Sciences, Patna. Spirometry and eosinophilic biomarkers such as blood eosinophil, sputum eosinophil, FeNO, and serum IL-5 were measured. All statistical calculations were conducted using SPSS (Statistical Package for the Social Science 22 version (SPSS, Chicago, IL, United States).

A total of 160 COPD patients were included in the study. The mean age of the study population was 61 (±10) years. Males (68.1%) and non-smokers (55%) respectively were predominant. The prevalence of bronchodilator reversibility was found to be 32%. There was a significant difference in eosinophil biomarker levels, of sputum eosinophil count, peripheral eosinophil count, and FeNO levels between the bronchodilator non-reversible and bronchodilator reversible groups. Serum IL-5 levels were higher and more significant in GOLD group D patients.

Eosinophils are crucial to the underlying inflammatory response in this subset of COPD patients, as evidenced by the observation that eosinophil biomarkers were significantly higher in COPD patients with bronchodilator reversibility. Also, sputum eosinophil levels had a better correlation in comparison to peripheral eosinophil level in this subset.