Ventilator-associated pneumonia. A multivariate analysis

Abstract

Objectives: To identify factors associated with the development of ventilator-associated pneumonia (VAP) and to examine the incidence of VAP in different intensive care unit (ICU) populations.

Design: An inception cohort study.

Setting: Barnes Hospital, St Louis, Mo, an academic tertiary care center.

Patients or other participants: A total of 277 consecutive patients required mechanical ventilation for longer than 24 hours from a medical ICU (75 patients), surgical ICU (100 patients), or cardiothoracic ICU (102 patients).

Interventions: Prospective patient surveillance and data collection.

Main outcome measures: Ventilator-associated pneumonia and ICU mortality.

Results: Ventilator-associated pneumonia occurred in 43 patients (15.5%). Stepwise logistic regression analysis identified four factors to be independently associated with VAP (P < .05): an organ system failure index of 3 or greater (adjusted odds ratio [AOR] = 10.2; 95% confidence interval [CI], 4.5 to 23; P < .001); patient age of 60 years or older (AOR = 5.1; 95% CI, 1.9 to 14.1; P = .002); prior administration of antibiotics (AOR = 3.1; 95% CI, 1.4 to 6.9; P = .004); and supine head positioning during the first 24 hours of mechanical ventilation (AOR = 2.9; 95% CI, 1.3 to 6.8; P = .013). Ventilator-associated pneumonia occurred more often in cardiothoracic patients (21.6%) compared with medical patients (9.3%) (P = .03). Patients with VAP also had a higher mortality (37.2%) than those without VAP (8.5%) (P < .001). An organ system failure index of 3 or greater (AOR = 16.1; 95% CI, 6.1 to 42; P < .001), a premorbid lifestyle score of 2 or greater (AOR = 3.1; 95% CI, 1.3 to 7.3; P = .012), and supine head positioning during the first 24 hours of mechanical ventilation (AOR = 3.1; 95% CI, 1.2 to 7.8; P = .016) were independently associated with mortality.

Conclusions: These data suggest potential interventions that might affect the incidence of VAP or outcome associated with VAP. Additionally, they indicate that different ICU populations may have different incidences of VAP.