Cost of intensive care unit-acquired bloodstream infections

Summary

Intensive care unit-acquired (ICU-acquired) bloodstream infections (BSI) are an important complication of critical illness. The objective of this study was to quantify the excess length of stay, mortality and cost attributable to ICU-acquired BSI. A matched cohort study was conducted in all adult ICUs in the Calgary Health Region between 1 May 2000 and 30 April 2003. One hundred and forty-four patients with ICU-acquired BSI were matched (1:1) to patients without ICU-acquired BSI. Patients with ICU-acquired BSI had a significantly increased median length of ICU stay {15.5 [interquartile range (IQR) 8–26] days vs 12 [IQR 7–18.5] days, P = 0.003} and median costs of hospital care [$85 137 (IQR $45 740–131 412) vs $67 879 (IQR $35 043–115 915, P = 0.02) compared with patients without ICU-acquired BSI. The median excess length of ICU stay was two days and the median cost attributable to ICU-acquired BSI was $12 321 per case. Sixty (42%) of the cases died compared with 37 (26%) of the controls [P = 0.002, attributable mortality 16%, 95% confidence interval (CI) 5.9–26.0%]. Patients with ICU-acquired BSI were at increased risk for in-hospital death (odds ratio = 2.64, 95%CI 1.40–5.29). Among survivor-matched pairs, the median excess lengths of ICU and hospital stay attributable to development of ICU-acquired BSI were two and 13.5 days, respectively, and the attributable cost due to ICU-acquired BSI was $25 155 per case survivor. Critically ill patients who develop ICU-acquired BSI suffer excess morbidity and mortality, and incur significantly increased healthcare costs. These data support expenditures on infection prevention and control programmes and further research into reducing the impact of these infections.

Introduction

Bloodstream infection (BSI) is a serious complication of critical illness.1, 2, 3, 4, 5, 6, 7, 8, 9, 10 Although a significant body of literature exists investigating specific aetiologies or foci of intensive-care-unit-acquired (ICU-acquired) BSI,11, 12, 13, 14, 15, 16 few studies have attempted to comprehensively define the impact of ICU-acquired BSI by determining the length of stay, cost and mortality attributable to these infections.4, 10, 17, 18 Dimick et al. conducted a cohort study in an American surgical ICU and found an increased length of stay and cost associated with catheter-related BSI.¹⁸ They did not assess attributable mortality. Rello et al. reported a matched study of catheter-related BSI in a mixed medical–surgical ICU in Spain and found increased costs associated with development of these infections.¹⁷ They did not observe a significant difference in either attributable length of stay or mortality although their study was small (49 matched pairs). DiGiovine et al. conducted another study with 68 matched pairs in an American medical ICU and found significantly increased costs and length of stay, but not mortality, associated with primary ICU-acquired BSI.¹⁰ Pittet et al. conducted the prior largest matched study to date (86 matched pairs) in a single American tertiary care surgical ICU, and found that ICU-acquired BSI was associated with significantly increased length of stay, mortality and cost.⁴ The present authors recently identified that development of an ICU-acquired BSI was independently associated with mortality in a cohort study conducted among all patients admitted to ICUs in the Calgary Health Region (CHR).¹⁹ However, costs and attributable length of stay were not assessed.

The summation of the available evidence to date supports the notion that ICU-acquired BSI results in excess length of stay and cost.4, 10, 17, 18 However, due to the small number of subjects from selected populations and crude methods of costing in many studies, significant variability in the estimates of attributable length of stay and cost has occurred.4, 10, 17, 18, 20 Furthermore, only the authors' previous cohort study and one other matched study conducted in a surgical ICU demonstrated a significantly increased risk of death attributable to ICU-acquired BSI.4, 19 Therefore, the authors conducted a matched cohort study within the population of all critically ill patients in a large Canadian health region over a three-year period to determine the attributable mortality, length of stay and cost associated with ICU-acquired BSI.