title: Comorbid pulmonary disease and risk of community-acquired pneumonia in COPD patients.
abstract: METHODS
  Risk of pneumonia in chronic obstructive pulmonary disease (COPD) patients due to comorbid pulmonary disease is not well understood.
  
  
  OBJECTIVE
  To compare factors associated with risk of community-acquired pneumonia (CAP) in COPD patients for those with and without lung cancer, bronchiectasis and/or history of active tuberculosis.
  
  
  METHODS
  Retrospective chart review of patients diagnosed with COPD (forced expiratory volume in 1 second/forced vital capacity < 0.70) between 2006 and 2010, including patient characteristics, occurrence of CAP and type of inhalation treatment. Pneumonia-free survivals were assessed using Kaplan-Meier curves. Factors associated with CAP were assessed using Cox's proportional hazard regression and expressed as adjusted hazard ratios (aHRs) with 95% confidence intervals (CIs).
  
  
  RESULTS
  Of 2630 patients, 402 (15.3%) developed CAP during follow-up. The likelihood of CAP increased with increased age (aHR 1.03, 95%CI 1.02-1.04), lower body mass index (BMI; aHR 0.97, 95%CI 0.95-1.00), lung cancer (aHR 3.81, 95%CI 2.88-5.05), bronchiectasis (aHR 2.46, 95%CI 1.70-3.55) and inhaled corticosteroid (ICS) containing treatment (aHR 1.60, 95%CI 1.30-1.96). ICS-containing treatment was associated with increased risk of CAP only for patients without comorbid pulmonary disease (aHR 1.68, 95%CI 1.30-2.17).
  
  
  CONCLUSIONS
  For COPD patients: 1) increased age, low BMI, lung cancer and bronchiectasis may increase the risk of CAP, and 2) without respiratory comorbid disease, ICS use increases the risk of CAP.
authors.affiliation: Division of Chest Medicine, Department of Internal Medicine, Changhua Christian Hospital, Changhua, Taiwan; Graduate Institute of Biomedical Sciences, National Chung Hsing University, Taichung, Taiwan.
authors.forename: S-H
authors.initials: SH
authors.lastname: Lin
authors.forename: B-C
authors.initials: BC
authors.lastname: Ji
authors.forename: Y-M
authors.initials: YM
authors.lastname: Shih
authors.forename: C-H
authors.initials: CH
authors.lastname: Chen
authors.forename: P-C
authors.initials: PC
authors.lastname: Chan
authors.forename: Y-J
authors.initials: YJ
authors.lastname: Chang
authors.forename: Y-C
authors.initials: YC
authors.lastname: Lin
authors.forename: C-H
authors.initials: CH
authors.lastname: Lin
mesh_terms: D000367:Age Factors; D000368:Aged; D015992:Body Mass Index; D001987:Bronchiectasis / Q000175:diagnosis / Q000453:epidemiology* / Q000503:physiopathology; D016009:Chi-Square Distribution; D017714:Community-Acquired Infections / Q000175:diagnosis / Q000453:epidemiology* / Q000503:physiopathology; D015897:Comorbidity; D018572:Disease-Free Survival; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D053208:Kaplan-Meier Estimate; D008168:Lung / Q000503:physiopathology; D008175:Lung Neoplasms / Q000175:diagnosis / Q000453:epidemiology* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D011014:Pneumonia / Q000175:diagnosis / Q000453:epidemiology* / Q000503:physiopathology; D016016:Proportional Hazards Models; D029424:Pulmonary Disease, Chronic Obstructive / Q000175:diagnosis / Q000453:epidemiology* / Q000503:physiopathology; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D014397:Tuberculosis, Pulmonary / Q000175:diagnosis / Q000453:epidemiology* / Q000503:physiopathology; D014797:Vital Capacity