Comorbid pulmonary disease and risk of community-acquired pneumonia in COPD patients

Abstract

Risk of pneumonia in chronic obstructive pulmonary disease (COPD) patients due to comorbid pulmonary disease is not well understood. 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. 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). 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). 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.