Relationship between blood eosinophils and clinical characteristics in a cross-sectional study of a US population-based COPD cohort ☆

•Blood eosinophils (Eos) may be related to COPD phenotypes and treatment response.•Most COPD subjects had Eos >2%; Eos were similarly distributed in normal lung function.•Older age, being male, and severe asthma were associated with Eos >2% in COPD.•Eos >2% in COPD was also associated with a lower risk of some co-morbidities.•Clinical significance and mechanism for these relationships require further study.