Hye Seon Kang, Chin Kook Rhee, Sung Kyoung Kim, Jin Woo Kim, Sang Haak Lee, Hyung Kyu Yoon, Joong Hyun Ahn, Yong Hyun Kim

We compared the clinical characteristics and treatment outcomes of patients with eosinophilic and neutrophilic COPD exacerbations requiring hospital admission. This was a retrospective multicenter study performed between January 2010 and December 2014. In all, 1,688 COPD patients admitted via the outpatient clinics or emergency departments of six university hospitals were enrolled. The patients were grouped by complete blood counts: eosinophilic group, >2% peripheral blood eosinophils, and neutrophilic group, >65% peripheral blood neutrophils or >11,000 leukocytes/mL. The patients with radiographic evidence of pneumonia at the time of admission, those with lung cancer, those admitted for treatment of other medical problems, and those who chronically used steroids were excluded. A total of 605 patients hospitalized with COPD exacerbations (177 eosinophilic and 380 neutrophilic) were included. Pulmonary functions, including the forced expiratory volume in 1 second and forced vital capacity, were better in patients with eosinophilic exacerbations. Treatment outcomes, including the rate of admission to the intensive care unit and mortality, were poorer in patients with neutrophilic exacerbations (4.5% vs 12.4%, P=0.004; 1.1% vs 4.5%, P=0.043, respectively). Congestive heart failure (odds ratio [OR] =3.40, 95% confidence interval [CI]: 1.28-9.01) and neutrophilic exacerbation (OR = 2.81, 95% CI: 1.21-6.52) were independent risk factors for intensive care unit admission. COPD patients with neutrophilic exacerbations experienced worse clinical outcomes than did those with eosinophilic exacerbations. The peripheral blood eosinophil count may be a useful predictor of clinical progress during hospitalization of COPD patients with acute exacerbations.