title: Implications of Emphysema and Lung Function for the Development of Pneumonia in Patients with Chronic Obstructive Pulmonary Disease.
abstract: BACKGROUND
  Chronic obstructive pulmonary disease (COPD) is sometimes complicated with pneumonia, but little is known about the risk factors that promote the development of pneumonia in COPD. These risk factors were evaluated in the present study.
  
  
  METHODS
  The data of 324 patients with COPD from a prospective multi-center observational cohort with obstructive lung disease were evaluated retrospectively. To identify risk factors for the development of pneumonia in COPD, the clinical and radiological data at enrollment and the time to the first episode of pneumonia were analyzed by Cox proportional hazard analysis.
  
  
  RESULTS
  The median follow-up time was 1,099 days and 28 patients (8.6%) developed pneumonia. The Cox analysis showed that post-bronchodilator forced expiratory volume in one second (FEV1, % of predicted) and the computed tomography (CT) emphysema extent (inspiratory V950) were independent risk factors for the development of pneumonia (post-bronchodilator FEV1: hazard ratio [HR], 0.97; 95% confidence interval [CI], 0.94-1.00; p=0.048 and inspiratory V950: HR, 1.04; 95% CI, 1.01-1.07; p=0.01).
  
  
  CONCLUSIONS
  Emphysema severity measured by CT and post-bronchodilator FEV1 are important risk factors for the development of pneumonia in COPD.
authors.affiliation: Department of Internal Medicine, Kangwon National University Hospital, Kangwon National University College of Medicine, Chuncheon, Korea.
authors.forename: Yoonki
authors.initials: Y
authors.lastname: Hong
authors.affiliation: Department 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.
authors.forename: Jae Seung
authors.initials: JS
authors.lastname: Lee
authors.affiliation: Department of Internal Medicine, Konkuk University School of Medicine, Seoul, Korea.
authors.forename: Kwang Ha
authors.initials: KH
authors.lastname: Yoo
authors.affiliation: Department of Internal Medicine, CHA Bundang Medical Center, CHA University, Seongnam, Korea.
authors.forename: Ji-Hyun
authors.initials: JH
authors.lastname: Lee
authors.affiliation: Department of Internal Medicine, Kangwon National University Hospital, Kangwon National University College of Medicine, Chuncheon, Korea.
authors.forename: Woo Jin
authors.initials: WJ
authors.lastname: Kim
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Department of Medicine, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Seong Yong
authors.initials: SY
authors.lastname: Lim
authors.affiliation: Department of Internal Medicine, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea.
authors.forename: Chin Kook
authors.initials: CK
authors.lastname: Rhee
authors.affiliation: Department 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.
authors.forename: Sang-Do
authors.initials: SD
authors.lastname: Lee
authors.affiliation: Department 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.
authors.forename: Yeon-Mok
authors.initials: YM
authors.lastname: Oh
keywords: Emphysema; Pneumonia; Pulmonary Disease, Chronic Obstructive; Risk Factors; Tomography, X-Ray Computed