Fast track — ArticlesClinical outcomes of health-care-associated infections and antimicrobial resistance in patients admitted to European intensive-care units: a cohort study
Introduction
Patients in intensive-care units are at high risk of health-care-associated infections because of intrinsic (eg, severity of illness or impaired immunity) and extrinsic (eg, mechanical ventilation or central line catheterisation) risk factors. In Europe, 3·0% of patients staying more than 2 days in intensive-care units acquire bloodstream infections, and 6·2% acquire pneumonia.1 Because of their precarious clinical states, common use of antibiotics, and high prevalence of antimicrobial resistance, patients are at high risk of infection with resistant pathogens.2
Data for clinical outcomes of infections and antimicrobial resistance are conflicting.3 A key issue is the contribution of host and infection factors. Data are very dependent on methods used to address differences in patients before infection (such as underlying disease severity), type of infection, and causative pathogen.3 Large studies are needed to provide detailed information on all these factors. Furthermore, modern statistical techniques are needed to account for the timing and duration of exposure4 and the competing risks caused by informative censoring (patients leaving an intensive-care unit alive are by definition in better health than are those that stay).5
We aimed to assess the excess mortality and length of stay in intensive-care units associated with bloodstream infections and pneumonia acquired in intensive care and for infections caused by pathogens with and without some common patterns of antimicrobial resistance. We provide separate estimates for Acinetobacter baumannii, Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus, because of their prevalence,1 pathogenicity, burden of antimicrobial resistance, and the availability of data for antimicrobial resistance (tracer phenotypes) in our database. This study was part of the Burden of Resistance and Disease in European Nations (BURDEN) project,6 which was financed by the European Union (EU), and followed previous EU-funded projects that developed and implemented a common protocol for the surveillance of infections associated with health care across Europe (eg, Hospitals in Europe Link for Infection Control through Surveillance and Improving Patient Safety in Europe [HELICS–IPSE]7).
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Study design and data collection
Our prospective cohort study is reported in accordance with the strengthening the reporting of observational studies in epidemiology (STROBE) guidelines.8 We obtained data routinely collected by national intensive-care unit surveillance networks in Europe according to the European protocol for surveillance of infections in intensive-care units (HELICS-ICU).9 Participation in national surveillance networks is voluntary, and as such not all European countries have such a network and the number of
Results
We obtained data for ten European countries (Austria, Belgium, Croatia, France, Italy, Latvia, Portugal, Slovakia, Scotland, and Spain) between 2005 and 2008. The final database provided data for 537 intensive-care units that admitted 119 699 patients for more than 2 days (table 1). During their stay, 8525 (7%) patients developed health-care-associated pneumonia and 4787 (4%) had bloodstream infections (any pathogen); 7675 (90%) pneumonias were ventilator-associated.
Table 2 shows descriptive
Discussion
Health-care-associated infections cause high excess mortality in critically ill patients, although antimicrobial resistance has a comparatively low additional effect. Overall estimates (for all four microorganisms) suggest that pneumonia double the risk of death, and bloodstream infections treble the risk, with an additional effect of antimicrobial resistance of around 20% although that was significant only for pneumonia. Antimicrobial resistance had no effect on length of stay in
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