Trends of bacterial colonisation and the risk of postoperative pneumonia in lung cancer patients with chronic obstructive pulmonary disease

Abstract

Background: Lung cancer patients with chronic obstructive pulmonary disease (COPD) have a high risk of developing postoperative pneumonia (POP). This study aims to investigate the impact of COPD on POP and the trends for perioperative bronchial colonisation by micro-organisms.

Methods: A retrospective chart review was made for 626 patients who underwent lung cancer surgeries at the Chiba University Hospital between 1996 and 2005. The patients were categorised as non-COPD (n=475) and COPD (forced expiratory volume in 1s/forced vital capacity (FEV1/FVC) <70%; n=151). All the patients had sputum and bronchial bacterial cultures examined for potentially pathogenic micro-organisms (PPMs). Risk factors for POP and mortality were analysed.

Results: Patients with COPD had a significantly higher incidence of POP (23/151, 15.2%) than those without COPD (17/475, 3.6%) (p<0.0001). Preoperative bronchial bacterial examinations showed that 50 of 475 patients without COPD (10.5%) had positive cultures, while the results for 30 of 151 patients with COPD (19.9%) were positive (p=0.0111). Only 31 of 548 patients (5.7%) who did not show any preoperative PPMs had POP, while nine of 78 patients (11.5%) who presented preoperative PPMs had POP (p=0.0469). The PPMs that emerged postoperatively were primarily Staphylococcus aureus (and Gram-negative bacilli (94.4% of PPMs), while they were seen less frequently preoperatively (46.5% of PPMs). Multivariate analysis demonstrated that advanced age and FEV1/FVC were independent risk factors for POP. Patients with POP had significantly worse long-term survivals than those without POP (p=0.0004).

Conclusion: COPD was a risk factor for POP. Staphylococcus aureus and Gram-negative bacilli should be targets for postoperative prophylactic antibiotic selection. Patients with POP had poor long-term survivals.