Does etiological investigation have an impact on the outcomes of community-acquired pneumonia? - A prospective cohort study

Introduction: There is lack of evidence that etiological investigation influences outcomes in community-acquired pneumonia (CAP). Guidelines recommend diverse approaches to this matter. Our aim was to find if etiological investigation has an impact on CAP management and outcomes.

Methods: Prospective cohort study, conducted over a two years' period, in a community-based hospital, including all adult patients with CAP. Univariate and multivariate logistic regression modeling were performed to understand the association of etiological identification with CAP outcomes, particularly hospital mortality.

Results: A total of 660 cases of CAP were included, with a mean±sd age of 74±15 years and 58.9% of males. Etiology was documented in 33% of cases. Antibiotic (ATB) was modified in 148 patients, in 51 (34%) motivated by microbiological results. There was no significant impact on hospital mortality of microbiological documentation (35.5% vs 31.2%, p=0.352), or the fact that ATB was modified due to microbiological findings (27.0% vs 36.9%, p=0.272). When stratified by 3 subgroups of risk for drug-resistant pathogens (zero, one or two risk factors: being bed-ridden and/or ATB use within 90 days), etiology identification still did not influence mortality. When adjusted for CURB-65, Charlson's index, being bed-ridden, having had ATB or hospitalization within 90 days or coming from long-term care facilities, microbial identification was not associated with lower mortality.

Conclusion: Etiological investigation of patients with CAP does not have an association with hospital mortality, irrespective of the risk for drug-resistant pathogens.