Background: The implications of bacteremia in critically ill patients are uncertain. Some reports suggest bacteremia is linked to higher mortality whereas others do not. These differences may, in part, be because of differences in patient cohorts. To address the potential independent relationship between bacteremia and outcome, we focused on critically ill trauma patients with ventilator-associated pneumonia (VAP), of whom a significant proportion had concomitant bacteremia. We tested the hypothesis that bacteremia was associated with death in trauma patients who developed VAP.
Methods: In this retrospective cohort study, we measured the incidence of bacteremia associated with VAP and compared the case-fatality rates between patients with and without bacteremia. We adjusted for other mortality risk factors and possible confounders in two ways. First, using forward conditional logistic regression and second, we calculated propensity scores and then adjusted for this score in a regression model.
Results: There were 554 with VAP. Patients with bacteremia had a 26% case-fatality rate (19 of 74 patients). Patients with VAP alone had a case-fatality rate of 12% (56 of 480 patients). The unadjusted relative risk (RR) for death associated with bacteremia was 2.2 (95% confidence interval = 1.4-3.5). After adjusting for age, acute physiology score, and severity of injury, patients with bacteremia had an increased risk of death compared with patients with VAP alone (adjusted odds ratio = 2.65, 95% confidence interval = 1.36-5.17). Our propensity score analysis resulted in a similar association between bacteremia and mortality.
Conclusions: VAP with bacteremia is associated with an increased mortality in comparison with VAP alone after severe traumatic injury.