title: Incidence and preventability of adverse events requiring intensive care admission: a systematic review.
abstract: OBJECTIVE
  Adverse events are unintended patient injuries or complications that arise from health care management resulting in death, disability or prolonged hospital stay. Adverse events that require critical care are a considerable financial burden to the health care system, but also their global impact on patients and society is probably underestimated. The objectives of this systematic review were to synthesize the best available evidence regarding the estimates of the incidence and preventability of adverse events that necessitate intensive care admission, to determine the type and consequences [mortality, length of intensive care unit (ICU) stay and costs] of these adverse events.
  
  
  METHODS
  MEDLINE (from 1966 to present), EMBASE (from 1974 to present) and CENTRAL (version 1-2010) were searched for studies reporting on unplanned admissions on ICUs. Several other sources were searched for additional studies. Only quantitative studies that used chart review for the detection of adverse events requiring intensive care admission were considered for eligibility. For the purposes of this systematic review, ICUs were defined as specialized hospital facilities which provide continuous monitoring and intensive care for acutely ill patients. Studies that were published in the English, Dutch, German, French or Spanish language were eligible for inclusion. Two reviewers independently extracted data and assessed the methodological quality of the included studies.
  
  
  RESULTS
  A total of 27 studies were reviewed. Meta-analysis of the data was not appropriate because of methodological and statistical heterogeneity between studies; therefore, results are presented in a descriptive way. The percentage of surgical and medical adverse events that required ICU admission ranged from 1.1% to 37.2%. ICU readmissions varied from 0% to 18.3%. Preventability of the adverse events varied from 17% to 76.5%. Preventable adverse events are further synthesized by type of event. Consequences of the adverse events included a mean length of ICU stay that ranged from 1.5 days to 10.4 days for the patient's first stay in ICU and mortality percentages between 0% and 58%.
  
  
  CONCLUSIONS
  Adverse events are an important reason for (re)admission to the ICU and a considerable proportion of these are preventable. It was not possible to estimate an overall incidence and preventability rate of these events as we found considerable heterogeneity. To decrease adverse events that necessitate ICU admission, several systems are recommended such as early detection of patients with clinical instability on general wards and the implementation of rapid response teams. Step-down or intermediate care units could be a useful strategy for patients who require monitoring to avoid ICU readmissions. However, the effectiveness of such systems needs to be investigated.
authors.affiliation: Hasselt University, Faculty of Medicine, Diepenbeek, Belgium. annemie.vlayen@uhasselt.be
authors.forename: Annemie
authors.initials: A
authors.lastname: Vlayen
authors.forename: Sandra
authors.initials: S
authors.lastname: Verelst
authors.forename: Geertruida E
authors.initials: GE
authors.lastname: Bekkering
authors.forename: Ward
authors.initials: W
authors.lastname: Schrooten
authors.forename: Johan
authors.initials: J
authors.lastname: Hellings
authors.forename: Neree
authors.initials: N
authors.lastname: Claes
mesh_terms: D006801:Humans; D007049:Iatrogenic Disease / Q000517:prevention & control; D015994:Incidence; D007362:Intensive Care Units / Q000706:statistics & numerical data*; D019300:Medical Errors / Q000517:prevention & control; D010343:Patient Admission / Q000706:statistics & numerical data*