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

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 13 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). Attributable mortality was 24.8%. The only variable associated with both BSI and hospital mortality was the LOD score determined 4 days before onset of BSI (odds ratio [OR], 1.10; 95% confidence interval [CI], 1.03 - 1.16;). The adjusted OR for hospital Pp. 0025 mortality among exposed patients (OR, 3.20; 95% CI, 2.30-4.43) decreased when the LOD score determined 4 days before onset of BSI was taken into account (OR, 3.02; 95% CI, 2.17 - 4.22; P < .001). 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.