Pneumonia in COPD patients has distinct clinical features

Sep 22 2014

By Joanna Lyford, Senior medwireNews Reporter

The aetiology and clinical features of community-acquired pneumonia (CAP) are different in people with chronic obstructive pulmonary disease (COPD) than in those without the lung condition, Spanish research demonstrates.

These differences are clinically relevant and should be taken into account when deciding how to manage pneumonia in patients with COPD, say Carolina Garcia-Vidal (University of Barcelona) and co-authors writing in PLoS One.

CAP is a frequent complication of COPD but the impact of lung disease on CAP course is unclear. To investigate, the team analysed information on 4121 patients who were hospitalised with CAP episodes over a 16-year period.

The prevalence of COPD in the cohort was 23.9%, which is in line with previous reports, say the authors. The median forced expiratory volume in 1 second was 50.0% and 57.8% had severe or very severe COPD.

There were many differences between patients with and without COPD. For instance, those with COPD were older and more often male, current or ex-smokers and heavy alcohol users. They were also more likely to have chronic comorbidities such as heart disease and cancer, and more likely to have been vaccinated against pneumococcus and influenza.

Regarding clinical features on admission, patients with COPD were more likely than others to have a cough, expectoration, purulent sputum, dyspnoea, tachypnoea and respiratory failure, and less likely to have fever, diarrhoea, headache, arthromyalgias, multilobar infiltrates, pleural effusion, empyema and bacteraemia.

Patients were COPD were admitted to hospital 3 days after the onset of clinical symptoms, versus 4 days in those without COPD.

Streptococcus pneumoniae was the most frequent causative organism in both groups, accounting for 36.5% of infections in patients with COPD and 33.4% in those without COPD.

However, Haemophilus influenzae and Gram-negative bacilli, especially Pseudomonas aeruginosa, were more frequent in patients with COPD than in those without, while Legionella pneumophila, atypical agents and aspirative pneumonia were less common.

Bacteraemia occurred less often in patients with COPD than in those without (9.1 vs 13.3%), as did pneumococcal bacteraemia. But bacteraemia caused by P. aeruginosa was more common.

In terms of outcomes, risk factors for mortality in the COPD group included multilobar pneumonia, P. aeruginosa aetiology and high-risk pneumonia severity index classes, with multivariate-adjusted odds ratios (OR) of 2.9, 19.1 and 10.3, respectively. Meanwhile, prior pneumococcal vaccination was protective against mortality, with an OR of 0.2.

Garcia-Vidal and co-authors write: “Although S. pneumoniae is the leading causative organism, Gram-negative bacilli and P. aeruginosa should also be taken into account, especially in patients with severe COPD receiving oxygen therapy at home.”

They add: “[P]rior pneumococcal vaccine was found to be protective, which should encourage physicians to increase the use of this vaccine in the COPD population.”

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