Eun Chong Yoon,1 So-My Koo,1 Hye Yun Park,2 Ho Cheol Kim,3 Woo Jin Kim,4 Ki Uk Kim,5 Ki-Suck Jung,6 Kwang Ha Yoo,7 Hyoung Kyu Yoon,8 Hee-Young Yoon1 1Division of Allergy and Respiratory Diseases, Department of Internal Medicine, Soonchunhyang University Seoul Hospital, Seoul, Republic of Korea; 2Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea; 3Department of Internal Medicine, Gyeongsang National University Changwon Hospital, Gyeongsang National University School of Medicine, Changwon, Republic of Korea; 4Department of Internal Medicine and Environmental Health Center, Kangwon National University, Chuncheon, Republic of Korea; 5Department of Internal Medicine, Pusan National University Hospital, Busan, Republic of Korea; 6Department of Internal Medicine, Hallym University Sacred Heart Hospital, Hallym University College of Medicine, Anyang, Republic of Korea; 7Department of Internal Medicine, Konkuk University School of Medicine, Seoul, Republic of Korea; 8Department of Internal Medicine, Yeouido St. Mary’s Hospital, College of Medicine, The Catholic University of Korea, Seoul, Republic of KoreaCorrespondence: Hee-Young Yoon, Soonchunhyang University Seoul Hospital, 59, Daesagwan-ro, Yongsan-gu, Seoul, 04401, Republic of Korea, Tel +82-10-8728-6950, Fax +82-2-709-9554, Email yhyoung85@schmc.ac.krPurpose: Chronic obstructive pulmonary disease (COPD) is a respiratory disease characterized by chronic inflammation. Acute exacerbation of COPD (AECOPD) manifests as acute worsening of respiratory symptoms and is associated with high morbidity and mortality. The aim of the present study was to evaluate the predictive value of white blood count (WBC) and its derived inflammatory biomarkers for AECOPD.Methods: From the Korean COPD Subgroup Study cohort, a prospective and multicenter observational study, 826 patients who had baseline complete blood count (CBC) and 3-year AECOPD data were included. Follow-up CBC data at 1 (n = 385), 2 (n = 294), and 3 (n = 231) years were collected for available patients. The primary outcome was the occurrence of AECOPD at 3 years. The risk of AECOPD was evaluated using a binary logistic analysis.Results: The cumulative incidences of 12-, 24-, and 36-month AECOPD were 47.6%, 60.5%, and 67.6%, respectively. Patients with AECOPD at 3 years had higher baseline WBC counts, neutrophil counts, neutrophil/lymphocyte ratio (NLR), and neutrophil/monocyte ratio than those without AECOPD. Higher WBC count, neutrophil count, and NLR were associated with the 3-year occurrence of AECOPD in the univariate analysis, but only the higher neutrophil count was a significant risk factor (odds ratio [OR] = 1.468; 95% confidence interval [CI]: 1.024– 2.104) in the covariates-adjusted analysis. In the analysis of changes in inflammatory parameters, a decrease in the platelet count (OR = 0.502; 95% CI: 0.280– 0.902) and NLR (OR = 0.535; 95% CI: 0.294– 0.974) at 2 years and an increase in the eosinophil count (OR = 2.130; 95% CI: 1.027– 4.416) at 3 years were significantly associated with AECOPD in the adjusted analysis.Conclusion: Our data suggest that a high baseline WBC count, particularly neutrophil count, was associated with a higher incidence of long-term AECOPD.Keywords: blood cell count, blood platelets, eosinophils, lymphocytes, neutrophils, pulmonary disease, chronic obstructive