Outcomes of patients hospitalized with community-acquired, health care-associated, and hospital-acquired pneumonia

Background: Traditionally, pneumonia has been classified as either community- or hospital-acquired. Although only limited data are available, health care-associated pneumonia has been recently proposed as a new category of respiratory infection. "Health care associated pneumonia" refers to pneumonia in patients who have recently been hospitalized, had hemodialysis, or received intravenous chemotherapy or reside in a nursing home or long-term care facility. Objective: To ascertain the epidemiology and outcome of community-acquired, health care-associated, and hospital-acquired pneumonia in adults hospitalized in internal medicine wards. Design: Multicenter, prospective observational study. Setting: 55 hospitals in Italy comprising 1941 beds. Patients: 362 patients hospitalized with pneumonia during two 1-week surveillance periods. Measurements: Cases of radiologically and clinically assessed pneumonia were classified as community-acquired, health care associated, or hospital-acquired and rates were compared. Results: Of the 362 patients, 61.6% had community-acquired pneumonia, 24.9% had health care-associated pneumonia, and 13.5% had hospital-acquired pneumonia. Patients with health care associated pneumonia had higher mean Sequential Organ Failure Assessment scores than did those with community-acquired pneumonia (3.0 vs. 2.0), were more frequently malnourished (11.1% vs. 4.5%, and had more frequent bilateral (34.4% vs. 19.7%) and multilobar (27.8% vs. 21.5%) involvement on a chest radiograph. Patients with health care-associated pneumonia also had higher fatality rates (17.8% [CI, 10.6% to 24.9%] vs. 6.7% [CI, 2.9% to 10.5%]) and longer mean hospital stay (18.7 days [CI, 15.9 to 21.5 days] vs. 14.7 days [CI, 13.4 to 15.9 days]). Logistic regression analysis revealed that depression of consciousness (odds ratio [OR], 3.2 [CI, 1.06 to 9.8]), leukopenia (OR, 6.2 [CI, 1.01 to 37.6]), and receipt of empirical antibiotic therapy not recommended by international guidelines (OR, 6.4 [CI, 2.3 to 17.6]) were independently associated with increased intrahospital mortality. Limitations: The number of patients with health care-associated pneumonia was relatively small. Microbiological investigations were not always homogeneous. The study included only patients with pneumonia that required hospitalization; results may not apply to patients treated as outpatients. Conclusion: Health care-associated pneumonia should be considered a distinct subset of pneumonia associated with more severe disease, longer hospital stay, and higher mortality rates. Physicians should differentiate between patients with health care-associated pneumonia and those with community-acquired pneumonia and provide more appropriate initial antibiotic therapy.