Excess risk of death from intensive care unit-acquired nosocomial bloodstream infections: A reappraisal

Abstract

Background. Overall rates of bloodstream infection (BSI) are often used as quality indicators in intensive care units (ICUs). We investigated whether ICU-acquired BSI increased mortality (by ≥10%) after adjustment for severity of infection at ICU admission and during the pre-BSI stay. Methods. We conducted a matched, risk-adjusted (1:n), exposed-unexposed study of patients with stays longer than 72 h in 12 ICUs randomly selected from the Outcomerea database. Results. Patients with BSI after the third ICU day (exposed group) were matched on the basis of risk-exposure time and mortality predicted at admission using the Three-Day Recalibrated ICU Outcome (TRIO) score to patients without BSI (unexposed group). Severity was assessed daily using the Logistic Organ Dysfunction (LOD) score. Of 3247 patients with ICU stays of >3 days, 232 experienced BSI by day 30 (incidence, 6.8 cases per 100 admissions); among them, 226 patients were matched to 1023 unexposed patients. Crude hospital mortality was 61.5% among exposed and 36.7% among unexposed patients (P < .0001). The estimated risk of death from BSI varied considerably according to the source and resistance of organisms, time to onset, and appropriateness of treatment. Conclusions. When adjusted for risk-exposure time and severity at admission and during the ICU stay, BSI was associated with a 3-fold increase in mortality, but considerable variation occurred across BSI subgroups. Focusing on BSI subgroups may be valuable for assessing quality of care in ICUs. © 2006 by the Infectious Diseases Society of America. All rights reserved.