Microbiology and Radiology of Pneumonia in COPD
Background: Pneumonia is associated with increased morbidity and mortality in COPD. We aimed to characterise the infectious aetiology and radiology of pneumonia in COPD and identify potential risk factors.
Methods: Retrospective analysis of medical records for patients with COPD (FEV1/FVC <0.70) admitted to 3 London hospitals between 01/01/2010 and 31/12/2012 with pneumonia or exacerbation (AECOPD). Patients were identified by COPD bundles. Admission CXRs were assessed by 2 independent observers. Pneumonia was defined as new consolidation on CXR.
Results: There were 235 pneumonia admissions and 706 for AECOPD. 43% of patients with radiological diagnosis of pneumonia had a diagnosis of pneumonia on their discharge summary. Patients admitted with pneumonia were more likely to have had a previous admission with pneumonia in the last year (21% v 6% p<0.01, RR 3.5) and be age ≥ 75 years (50% vs 36% p=0.01, RR 1.58). There was no difference between pneumonia and AECOPD for mean FEV1 % predicted (40 +/- 18 v 41 +/- 19) or proportion of patients using inhaled corticosteroids (79% v 83%).
Gram negative organisms were identified in 21% of pneumonias and 13% of exacerbations. The most commonly isolated organism was Pseudomonas aeruginosa (7% of pneumonia, 5% of AECOPD). 44% of pneumonias were lobar, 42% multifocal and 13% bibasal.
Conclusions: Incidence of pneumonia in COPD is likely to be underestimated. The most commonly isolated bacteria were gram negatives which may not respond to current antibiotic guidelines for community acquired pneumonia. Risk factors for pneumonia are previous history of pneumonia and age≥ 75 years.