The effect of late-onset ventilator-associated pneumonia in determining patient mortality.
OBJECTIVE
To determine whether the development of late-onset ventilator-associated pneumonia (VAP) is associated with an increased risk of hospital mortality.


METHODS
Prospective cohort study.


METHODS
ICUs of two university-affiliated teaching hospitals.


METHODS
Three hundred fourteen patients admitted to an ICU who required mechanical ventilation for greater than 5 days.


METHODS
Prospective patient surveillance and data collection.


METHODS
The primary outcome measures were the development of late-onset VAP (ie, occurring > 96 h after intubation) and hospital mortality.


RESULTS
Late-onset VAP was observed in 87 patients (27.7%). Thirty-four (39.1%) patients with late-onset VAP died during hospitalization compared with 85 patients (37.4%) without late-onset VAP (relative risk, 1.04; 95% confidence interval [CI], 0.76 to 1.43). Twenty patients (6.4%) developed late-onset VAP due to a "high-risk" pathogen (ie, Pseudomonas aeruginosa, Acinetobacter sp, Xanthomonas maltophilia) with an associated mortality rate of 65%. Stepwise logistic regression analysis identified five variables as independent risk factors for hospital mortality (p < 0.05): an organ system failure index of 3 or greater (adjusted odds ratio [AOR], 3.4; 95% CI, 2.0 to 5.8; p < 0.001), having a nonsurgical diagnosis (AOR, 2.1; 95% CI, 1.3 to 3.6; p = 0.002), a premorbid lifestyle score of 2 or greater (AOR, 1.8; 95% CI, 1.1 to 2.9; p = 0.015), acquiring late-onset VAP due to a "high-risk" pathogen (AOR, 3.4; 95% CI, 1.2 to 10.0; p = 0.025), and having received antacids or histamine type-2 receptor antagonists (AOR, 1.7; 95% CI, 1.0 to 2.9; p = 0.034). Additionally, we found the occurrence of late-onset VAP due to high-risk pathogens to be the most important predictor of hospital mortality among patients developing VAP (AOR, 5.4; 95% CI, 2.8 to 10.3; p = 0.009).


CONCLUSIONS
Nosocomial pneumonia due to certain high-risk microorganisms is an independent risk factor for hospital mortality among patients requiring prolonged mechanical ventilation. We suggest that future investigations of late-onset VAP stratify patient outcomes according to the distribution of high-risk pathogens when reporting their results.
D018806:APACHE; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D016001:Confidence Intervals; D003428:Cross Infection / Q000209:etiology*; D005260:Female; D017052:Hospital Mortality; D006801:Humans; D007362:Intensive Care Units; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D018410:Pneumonia, Bacterial / Q000209:etiology*; D011446:Prospective Studies; D012121:Respiration, Artificial / Q000009:adverse effects*; D012307:Risk Factors; D013997:Time Factors