Mortality, morbidity, and disease severity of patients with aspiration pneumonia

Abstract

Background: Aspiration pneumonia is a common syndrome, although less well characterized than other pneumonia syndromes. We describe a large population of patients with aspiration pneumonia.

Methods: In this retrospective population study, we queried the electronic medical records at a tertiary-care, university-affiliated hospital from 1996 to 2006. Patients were initially identified by International Classification of Diseases, 9th Revision code 507.x; subsequent physician chart review excluded patients with aspiration pneumonitis and those without a confirmatory radiograph. Patients with community-acquired aspiration pneumonia were compared to a contemporaneous population of community-acquired pneumonia (CAP) patients. We compared CURB-65 (a clinical prediction rule based on Confusion, Uremia, Respiratory rate, Blood Pressure, and age)-predicted mortality with actual 30-day mortality.

Results: We identified 628 patients with aspiration pneumonia, of which 510 were community-acquired. Median age was 77 years, with 30-day mortality of 21%. Compared to CAP patients, patients with community-acquired aspiration pneumonia had more frequent inpatient admission (99% vs 58%) and intensive care unit admission (38% vs 14%), higher Charlson comorbidity index (3 vs 1), and higher prevalence of do not resuscitate/intubate orders (24% vs 11%). CURB-65 predicted mortality poorly in aspiration pneumonia patients (area under the curve, 0.66).

Conclusions: Patients with community-acquired aspiration pneumonia are older, have more comorbidities, and demonstrate higher mortality than CAP patients, even after adjustment for age and comorbidities. CURB-65 poorly predicts mortality in this population.

Figure 1

Inclusion and exclusion criteria.

Figure 2

Receiver-operating characteristic curve, comparing the eCURB score against 30-day mortality in patients with typical community-acquired pneumonia and in patients with community-acquired aspiration pneumonia. These curves statistically differ, p < 0.0001. CAP = Community-acquired pneumonia

Figure 3

Receiver-operating characteristic curve, comparing the IDSA/ATS minor criteria for severe community-acquired pneumonia against ICU admission in patients with typical community-acquired pneumonia and in patients with community-acquired aspiration pneumonia. These curves statistically differ, p < 0.0001.

Figure 4

Distribution of bacterial organism recovered from 628 patients with aspiration pneumonia. MRSA = methicillin resistant S. aureus. MSSA = methicillin sensitive S. aureus. Other = B. cereus (1), Serratia marcescens (1), Nocardia species (1), Acinetobacter bauminii (1), ccapnocytophagia (1), E. corrodens (1), Proteus (1), S. cerevisiae (1). Percentages are expressed as a fraction of 628 patients. Note that the total exceeds 100% due to polymicrobial infection. Viral, fungal, and AFB cultures were not routinely obtained, and not included in this graphic.