Impact of aspiration pneumonia in patients with community-acquired pneumonia and healthcare-associated pneumonia: a multicenter retrospective cohort study.

Background And Objective: Aspiration pneumonia is one of the common presentations of community-acquired pneumonia (CAP) and healthcare-associated pneumonia (HCAP). However, its significance has not yet been fully evaluated due to the difficulties associated with the diagnosis of this condition. This study aimed to evaluate the impact of objectively defined aspiration pneumonia on patients' prognosis with CAP and HCAP.

Methods: This is a multicenter retrospective cohort study consisting of 417 CAP and 220 HCAP patients. We defined aspiration pneumonia as having both risk factors for aspiration (dysphagia due to a neurological disorder, or disturbance of consciousness) and evidence of gravity-dependent opacity on chest computed tomography (CT). The prognostic factors for 30-day mortality were analysed.

Results: One hundred sixteen (18%) patients met the definition of aspiration pneumonia, 72 (11%) patients had risks for aspiration alone, 129 (20%) patients had CT findings consistent with aspiration alone, and 320 (50%) patients had neither. Patients diagnosed with aspiration pneumonia had a significantly worse survival than those with risk factors alone (P = 0.001), CT findings of aspiration alone (P = 0.009) and neither (P < 0.001). A multivariate analysis indicated that aspiration pneumonia was independently associated with increased 30-day mortality (adjusted hazard ratio 5.690, P < 0.001) after adjusting for other variables, including the category of pneumonia, performance status, the severity score (CURB-65) and treatment failure due to resistant pathogens.

Conclusion: Aspiration pneumonia may be a significant predictor of mortality among CAP and HCAP patients. Therefore, the concept of aspiration pneumonia should be considered in the guidelines for these types of pneumonia.