The attributable morbidity and mortality of ventilator-associated pneumonia in the critically ill patient

To evaluate the attributable morbidity and mortality of ventilator-associat ed pneumonia (VAP) in intensive care unit (ICU) patients, we conducted a pr ospective, matched cohort study. Patients expected to be ventilated for > 4 8 h were prospectively followed for the development of VAP. To determine th e excess ICU stay and mortality attributable to VAP, we matched patients wi th VAP to patients who did not develop clinically suspected pneumonia. We a lso conducted sensitivity analyses to examine the effect of different popul ations, onset of pneumonia, diagnostic criteria, causative organisms, and a dequacy of empiric treatment on the outcome of VAP. One hundred and seventy -seven patients developed VAP. As compared with matched patients who did no t develop VAP, patients with VAP stayed in the ICU for 4.3 d (95% confidenc e interval [Cl]: 1.5 to 7.0 d) longer and had a trend toward an increase in risk of death (absolute risk increase: 5.8%; 95% CI: -2.4 to 14.0 d; relat ive risk (RR) increase: 32.3%; 95% CI: -20.6 to 85.1%). The attributable IC U length of stay was longer for medical than for surgical patients (6.5 ver sus 0.7 d, p < 0.004), and for patients infected with "high risk" organisms as compared with "low risk" organisms (9.1 d versus 2.9 d). The attributab le mortality was higher for medical patients than for surgical patients (RR increase of 65% versus -27.3%, p = 0.04). Results were similar for three d ifferent VAP diagnostic criteria. We conclude that VAP prolongs ICU length of stay and may increase the risk of death in critically ill patients. The attributable risk of VAP appears to vary with patient population and infect ing organism.