Increased risk of bloodstream and urinary infections in intensive care unit (ICU) patients compared with patients fitting ICU admission criteria treated in regular wards

doi:10.1016/j.jhin.2004.07.028

Journal of Hospital Infection

Volume 59, Issue 4, April 2005, Pages 331-342

https://doi.org/10.1016/j.jhin.2004.07.028 Get rights and content

Summary

Critically ill patients, eligible for admission into intensive care units (ICUs), are often hospitalized in other wards due to a lack of ICU beds. Differences in morbidity between patients managed in ICUs and elsewhere are unknown, specifically the morbidity related to hospital-acquired infection. Patients fitting ICU admission criteria were identified by screening five entire hospitals on four separate days. Hospital infections within a 30-day follow-up period were compared in ICU patients and in patients on other wards using Kaplan–Meier curves. Residual differences in the patients' case mix between ICUs and other wards were adjusted for utilizing multivariate Cox models. Of 13 415 patients screened, 668 were critically ill. The overall infection rates (per 100 patient-days) were 1.2 for bloodstream infection (BSI) and 1.9 for urinary tract infection (UTI). The adjusted hazard ratios in ICU patients compared with patients on regular wards were 3.1 (P<0.001) for BSI and 2.5 (P<0.001) for UTI. This increased risk persisted even after adjusting for the disparity in the number of cultures sent from ICUs compared with ordinary wards. No interdepartmental differences were found in the rates of pneumonia, surgical wound infections and other infections. Minimizing the differences between characteristics of patients hospitalized in ICUs and in other wards, and controlling for the higher frequency of cultures sent from ICUs did not eliminate the increased risk of BSI and UTI associated with admission into ICUs.

Introduction

Interest in the outcome of critically ill patients hospitalized in intensive care units (ICUs) and in other wards is growing, as more patients are now surviving¹ to occupy hospital beds. In Israel,² as in European countries,3, 4 there is a shortage of ICU beds due to financial constraints. Therefore, many critically ill patients are treated in regular hospital wards.4, 5 In Israel, only 2% of hospital beds are allocated to general and respiratory intensive care, and not all of them are operative due to a shortage of nursing staff.

A recent study⁶ in Israel screened five acute-care hospitals to identify patients who met ICU admission criteria, who were hospitalized anywhere in the hospitals. Of a total of 13 415 hospitalized patients screened, 5.5% were found to fit ICU admission criteria. Of these, half were treated in regular wards.

Although ICU admission may improve survival,7, 8, 9 the more invasive monitoring employed in ICUs may lead to more infections,10, 11, 12 especially when the patient's hospital stay is prolonged. Hospital-acquired infections (HAIs) among critically ill patients contribute to morbidity and mortality,13, 14, 15, 16, 17, 18 and increase hospital costs.19, 20 Reported prevalence rates of infection for entire hospital populations vary from 6 to 12%,10, 21, 22, 23, 24, 25, 26 while for ICU patients, the rates are three to seven times higher.10, 12, 21, 27, 28 Publications comparing the rates of infection in ICUs with regular hospital wards are numerous.12, 16, 21, 25, 26, 28, 29, 30 However, in most of these studies, the vast differences in the severity of illness (case mix) between patients in ICUs and regular wards preclude drawing conclusions about the risk of infection in ICUs compared with ordinary wards.

The objective of this study was to compare similar patients in ICUs and on ordinary wards for morbidity associated with HAI.

Section snippets

Screening study criteria

Prior to the study, the directors of all ICUs in Israel developed consensus ICU admission criteria (study criteria). These were based mainly on the Task Force of the Society of Critical Care Medicine (SCCM)'s guidelines for intensive care admission, discharge and triage.31, 32, 33 While these criteria provided widely accepted expert opinion, they were not formally validated. The Israeli criteria were slightly modified to include some treatment modalities, which were not included in the SCCM

Results

Data on infections were available on 701 (95%) of the 736 patients who met ICU admission criteria. Thirty-three patients who died or who were discharged within 48 h of entry were excluded because their hospital stay was too short to allow diagnosis of new infection. This left 668 patients as the study population for this report. Of these, 186 (27.8%) were admitted to ICUs on the day of deterioration, and contributed 2791 patient-days to ICUs. If not removed from the analysis, these patients

Discussion

The unique feature of the present study is the comparison of infections among patients who met ICU admission criteria, who were treated either in an ICU or elsewhere. Previous comparisons28, 29, 30 between infections in ICUs and ordinary wards have always assumed that ICU patients were sicker. Thus, higher rates of infection in ICUs were accepted as an unavoidable phenomenon in view of the type of patient treated there. Under the present study design, the entire hospital population was screened

Acknowledgements

The authors would like to thank the infectious disease specialists (Mervin Shapira, Collin Block, Pablo Yagupsky, Nehama Peled, Raul Raz and Levkovitz Slavio) and the medical registration offices of the five participating hospitals.

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Increased risk of bloodstream and urinary infections in intensive care unit (ICU) patients compared with patients fitting ICU admission criteria treated in regular wards

Summary

Introduction

Section snippets

Screening study criteria

Results

Discussion

Acknowledgements

Lancet

J Hosp Infect

Chest

J Hosp Infect

J Hosp Infect

J Hosp Infect

J Hosp Infect

J Hosp Infect

Crit Care Med

Am J Infect Control

J Crit Care

Am J Cardiol

Improved survival of patients with acute respiratory distress syndrome (ARDS): 1983–1993

JAMA

Rationing intensive care—physician responses to a resource shortage

N Engl J Med

Triage considerations in medical intensive care

Arch Intern Med

Prospective evaluation of patients refused admission to an intensive care unit: triage, futility and outcome

Intens Care Med

Evaluation of triage decisions for intensive care admission

Crit Care Med

Improved survival in cancer patients requiring mechanical ventilatory support: impact of noninvasive mechanical ventilatory support

Crit Care Med

The prevalence of nosocomial infection in intensive care units in Europe

JAMA

Prevalence and risk factors for nosocomial infections in four university hospitals in Switzerland

Infect Control Hosp Epidemiol

Influence of nosocomial infection on mortality rate in an intensive care unit

Crit Care Med

Nosocomial infection and fatality in medical and surgical intensive care unit patients

Arch Intern Med

Mortality and the increase in length of stay attributable to the acquisition of Acinetobacter in critically ill patients

Crit Care Med

A one-year prospective study of nosocomial bacteremia in ICU and non-ICU patients and its impact on patient outcome

J Hosp Infect

Attributable morbidity and mortality of catheter-related septicemia in critically ill patients: a matched, risk-adjusted, cohort study

Infect Control Hosp Epidemiol