Risk of Mortality with a Bloodstream Infection Is Higher in the Less Severely Ill at Admission

Johns Hopkins University, Baltimore, Maryland, United States
American Journal of Respiratory and Critical Care Medicine (Impact Factor: 13). 04/2005; 171(6):616-20. DOI: 10.1164/rccm.200407-916OC
Source: PubMed


Health care-associated bloodstream infections are common in critically ill patients; however, investigators have had difficulty in quantifying the clinical impact of these infections given the high expected mortality among these patients.
To estimate the impact of health care-associated bloodstream infections on in-hospital mortality after adjusting for severity of illness at critical care admission.
A cohort of medical and surgical intensive care unit patients.
Severity of illness at admission, bloodstream infection, and in-hospital mortality.
Among the 2,783 adult patients, 269 developed unit-associated bloodstream infections. After adjusting for severity of illness, patients with a lower initial severity of illness who developed an infection had a greater than twofold higher risk for in-hospital mortality (hazard ratio [HR] = 2.42, 95% confidence interval [CI] 1.70, 3.44) when compared with patients without infection and with a similar initial severity of illness. In contrast, patients with a higher initial severity of illness who subsequently developed an infection did not have an increased risk for in-hospital mortality (HR = 0.96, 95%CI 0.76, 1.23) when compared with patients without infection but with a similar initial severity of illness.
These results suggest that these infections in less ill patients have a higher attributable impact on subsequent mortality than in more severely ill patients. Focusing interventions to prevent bloodstream infections in less severely ill patients would be expected to have a greater benefit in terms of mortality reduction.

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Available from: Trish M Perl
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    • "The structure function activity of lipid-A, the biologically active component of endotoxin differs for different GN bacteria [45]. Furthermore, the impact of underlying risk of death is a key factor in the clinical setting [46,47] but is difficult to investigate in laboratory studies [48-52]. These factors illustrate the 'disconnect' between attempts to study sepsis in animal models versus the clinical setting [50]. "
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    ABSTRACT: Introduction The interdependence between endotoxemia, gram negative (GN) bacteremia and mortality has been extensively studied. Underlying patient risk and GN bacteremia types are possible confounders of the relationship. Methods Published studies with ≥10 patients in either ICU or non-ICU settings, endotoxemia detection by limulus assay, reporting mortality proportions and ≥1 GN bacteremia were included. Summary odds ratios (OR) for mortality were derived across all studies by meta-analysis for the following contrasts: sub-groups with either endotoxemia (group three), GN bacteremia (group two) or both (group one) each versus the group with neither detected (group four; reference group). The mortality proportion for group four is the proxy measure of study level risk within L'Abbé plots. Results Thirty-five studies were found. Among nine studies in an ICU setting, the OR for mortality was borderline (OR <2) or non-significantly increased for groups two (GN bacteremia alone) and three (endotoxemia alone) and patient group one (GN bacteremia and endotoxemia co-detected) each versus patient group four (neither endotoxemia nor GN bacteremia detected). The ORs were markedly higher for group one versus group four (OR 6.9; 95% confidence interval (CI), 4.4 -to 11.0 when derived from non-ICU studies. The distributions of Pseudomonas aeruginosa and Escherichia coli bacteremias among groups one versus two are significantly unequal. Conclusions The co-detection of GN bacteremia and endotoxemia is predictive of increased mortality risk versus the detection of neither but only in studies undertaken in a non-ICU setting. Variation in GN bacteremia species types and underlying risk are likely unrecognized confounders in the individual studies.
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