The reproducibility of COPD blood eosinophil counts

Post hoc and pre-specified analyses of chronic obstructive pulmonary disease (COPD) randomised controlled trials have shown that higher blood eosinophil counts predict greater inhaled corticosteroid (ICS) effects on exacerbation prevention [1–5]. COPD patients with higher blood eosinophil counts have greater eosinophil numbers in sputum, bronchoalveolar lavage and bronchial tissue, and more reticular basement membrane thickening [6]. Furthermore, increased sputum eosinophil counts are associated with reduced airway presence of pathogenic bacteria in COPD [7]. Eosinophilic COPD therefore has distinct biological features associated with increased ICS responsiveness. Blood eosinophil counts in COPD are stable over the long term <http://ow.ly/aDlN30jVBCg>