The distribution of blood eosinophils and the related clinical characteristics in chronic obCOPD patients

Objective: To analyze the distribution of blood eosinophils (EOS) in COPD patients in the community and outpatient clinics, and to study the clinical characteristics and influencing factors of COPD patients with high EOS counts. Methods: This study included 237 patients with stable COPD, of which the median age was 68 years and males accounted for 81.2%. There were 45 community patients from the China Pulmonary Health study conducted in 2012-2013 and another 192 outpatients who attended the Respiratory Department of Peking University Third Hospital from August 2013 to November 2014 or from September 2015 to May 2018. Taking 100 cells/μl as the cut-off value, it was divided into high EOS group (146 people, 61.6%) and low EOS group (91 people, 38.4%). We compared demographic characteristics, respiratory symptoms, acute exacerbation, lung function, inflammation, imaging and other indicators. Results: The median EOS count of community patients was 110.4 cells/μl, and that of outpatients was 110.0 cells/μl. There was no statistically significant difference in the distribution of blood EOS among community and outpatients. The median EOS count of the general population was 110.0 cells/μl, and the median percentage was 1.8%. EOS≥300 cells/μl accounted for 11.4%. In the high EOS group, the percentage of male gender was higher (85.6% vs 74.7%), the GOLD grade was more severe, and the percentage of neutrophils was lower (61.70% vs 64.70%) (P<0.05 for these three characteristics). After multivariate analysis, the high EOS group was closely related to older age (OR=1.035, 95%CI:1.004-1.067, P=0.029), heavier GOLD grade (P=0.015) and lower percentage of neutrophils (OR=0.956, 95%CI:0.923-0.991, P=0.015). Conclusion: The distribution of blood EOS of COPD patients between the community and the outpatient clinics is not significantly different. About 60% of COPD patients have blood EOS≥100 cells/μl, which is associated with advanced age, male, severe airflow limitation, and low neutrophils.