Blood eosinophil count as a prognostic biomarker in COPD

Yeon-Mok Oh,1,* Keu Sung Lee,2,* Yoonki Hong,3,* Sung Chul Hwang,2 Jae Yeol Kim,4 Deog Keom Kim,5 Kwang Ha Yoo,6 Ji-Hyun Lee,7 Tae-Hyung Kim,8 Seong Yong Lim,9 Chin Kook Rhee,10 Hyoung Kyu Yoon,11 Sang Yeub Lee,12 Yong Bum Park,13 Jin Hee Jung,14 Woo Jin Kim,3 Sang-Do Lee,1 Joo Hun Park2 1Department of Pulmonary and Critical Care Medicine and Clinical Research Center for Chronic Obstructive Airway Diseases, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea; 2Department of Pulmonary and Critical Care Medicine, Ajou University School of Medicine, Suwon, Korea; 3Department of Internal Medicine and Environmental Health Center, Kangwon National University, Kangwon National University Hospital, Chuncheon, Korea; 4Department of Internal Medicine, Chung-Ang University College of Medicine, Seoul, Korea; 5Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Seoul Metropolitan Government-Seoul National University Boramae Medical Center, Seoul National University College of Medicine, Seoul, Korea; 6Department of Internal Medicine, Konkuk University School of Medicine, Seoul, Korea; 7Department of Internal Medicine, CHA Bundang Medical Center, CHA University, Seongnam, Korea; 8Division of Pulmonology, Department of Internal Medicine, Hanyang University College of Medicine, Guri, Korea; 9Division of Pulmonary and Critical Care Medicine, Department of Medicine, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Korea; 10Division of Pulmonary, Allergy and Critical Care Medicine, Department of Internal Medicine, Seoul St Mary’s Hospital, Catholic University of Korea, Seoul, Korea; 11Division of Respiratory and Critical Care Medicine, Department of Internal Medicine, College of Medicine, Korea University Anam Hospital, Seoul, Korea; 12Division of Respiratory and Critical Care Medicine, Department of Internal Medicine, College of Medicine, Korea University Anam Hospital, Seoul, Korea; 13Division of Pulmonary, Allergy and Critical Care Medicine, Department of Internal Medicine, Hallym University Kangdong Sacred Heart Hospital, Seoul, Korea; 14Department of Biomedical Informatics, Ajou University School of Medicine, Suwon, Korea *These authors contributed equally to this work Background: High blood eosinophil count is a predictive biomarker for response to inhaled corticosteroids in prevention of acute exacerbation of COPD, and low blood eosinophil count is associated with pneumonia risk in COPD patients taking inhaled corticosteroids. However, the prognostic role of blood eosinophil count remains underexplored. Therefore, we investigated the associated factors and mortality based on blood eosinophil count in COPD.Methods: Patients with COPD were recruited from 16 hospitals of the Korean Obstructive Lung Disease cohort (n=395) and COPD in Dusty Area cohort (n=234) of Kangwon University Hospital. The two merged cohorts were divided based on blood eosinophil count into three groups: high (≥5%), middle (2%–5%), and low (