Do either early warning systems or emergency response teams improve hospital patient survival? A systematic review.

BACKGROUND: For critical care to be effective it must have a system in place to achieve optimal care for the deteriorating ward patient.

OBJECTIVES: To systematically review the available literature to assess whether either early warning systems or emergency response teams improve hospital survival. In the event of there being a lack of evidence regarding hospital survival, secondary outcome measures were considered (unplanned ICU admissions, ICU mortality, length of ICU stay, length of hospital stay, cardiac arrest rates).

METHODS: The Ovid Medline, EMBASE, CINAHL, Web of Science, Cochrane library and NHS databases were searched in September 2012 along with non-catalogued resources for papers examining the effect of early warning systems or emergency response teams on hospital survival. Inclusion criteria were original clinical trials and comparative studies in adult inpatients that assessed either an early warning system or emergency response team against any of the predefined outcome measures. Exclusion criteria were previous systematic reviews, non-English abstracts and studies incorporating paediatric data. Studies were arranged in to sections focusing on the following interventions: Early warning systems - Single parameter systems - Aggregate weighted scoring systems (AWSS) Emergency response teams - Medical emergency teams - Multidisciplinary outreach services . In each section an appraisal of the level of evidence and a recommendation has been made using the SIGN grading system.

RESULTS: 43 studies meeting the review criteria were identified and included for analysis. 2 studies assessed single parameter scoring systems and 4 addressed aggregate weighted scoring systems. A total of 20 studies examined medical emergency teams and 22 studies examined multidisciplinary outreach teams.

LIMITATIONS: The exclusion of non English studies and those including paediatric patients does limit the applicability of this review.

CONCLUSIONS: Much of the available evidence is of poor quality. It is clear that a 'whole system' approach should be adopted and that AWSS appear to be more effective than single parameter systems. The response to deterioration appears most effective when a clinician with critical care skills leads it. The need for service improvement differs between health care systems.