Chronic obstructive pulmonary disease (COPD) is a frequent comorbidity in patients with community acquired pneumonia (CAP).

We investigated the impact of COPD on outcomes of CAP patients.We prospectively studied the clinical presentation of 1379 patients admitted with CAP during a 4 year-period. A comparative analysis of disease severity and course was performed between 212 patients with COPD, as confirmed by spirometry, and 1167 non-COPD patients.

COPD patients (median FEV1=47.7±16.3 % predicted) were older and more likely received previous antibiotics (37.1% vs. 28.3%, p<0.01) than those without COPD. They presented with more severe respiratory failure, (Pa,O2/FIO2 (270.4 vs. 287.8, p<0.01) and more severe pneumonia (PSI, 118.3 vs. 108.5; p<0.001). However, COPD patients had less multilobar infiltration (44 (21%) vs. 349 (30%), p<0.01) and less pulmonary complications (24 [14%] vs. 241 [24%]; p<0.01). A total of 89 patients (6.5%) died within 30 days. COPD patients had not different 30-days mortality rate compared to non-COPD patients (9 patients [4.2%] vs. 81[7%], p=0.14).

Despite worse clinical presentation COPD patients had a similar mortality compared to non-COPD patients. Previous antibiotic treatment and the decreased incidence pulmonary complications in COPD may account for these findings.