Epidemiology and outcomes of health-care-associated pneumonia: results from a large US database of culture-positive pneumonia.

CONTEXT Traditionally, pneumonia developing in patients outside the hospital is categorized as community acquired, even if these patients have been receiving health care in an outpatient facility. Accumulating evidence suggests that health-care-associated infections are distinct from those that are truly community acquired. OBJECTIVE To characterize the microbiology and outcomes among patients with culture-positive community-acquired pneumonia (CAP), health-care-associated pneumonia (HCAP), hospital-acquired pneumonia (HAP), and ventilator-associated pneumonia (VAP). DESIGN AND SETTING A retrospective cohort study based on a large US inpatient database. PATIENTS A total of 4,543 patients with culture-positive pneumonia admitted into 59 US hospitals between January 1, 2002, and December 31, 2003, and recorded in a large, multi-institutional database of US acute-care hospitals (Cardinal Health-Atlas Research Database; Cardinal Health Clinical Knowledge Services; Marlborough, MA). MAIN MEASURES Culture data (respiratory and blood), in-hospital mortality, length of hospital stay (LOS), and billed hospital charges. RESULTS Approximately one half of hospitalized patients with pneumonia had CAP, and > 20% had HCAP. Staphylococcus aureus was a major pathogen in all pneumonia types, with its occurrence markedly higher in the non-CAP groups than in the CAP group. Mortality rates associated with HCAP (19.8%) and HAP (18.8%) were comparable (p > 0.05), and both were significantly higher than that for CAP (10%, all p < 0.0001) and lower than that for VAP (29.3%, all p < 0.0001). Mean LOS varied significantly with pneumonia category (in order of ascending values: CAP, HCAP, HAP, and VAP; all p < 0.0001). Similarly, mean hospital charge varied significantly with pneumonia category (in order of ascending value: CAP, HCAP, HAP, and VAP; all p < 0.0001). CONCLUSIONS The present analysis justified HCAP as a new category of pneumonia. S aureus was a major pathogen of all pneumonias with higher rates in non-CAP pneumonias. Compared with CAP, non-CAP was associated with more severe disease, higher mortality rate, greater LOS, and increased cost.