Fast track — ArticlesIntroduction of the medical emergency team (MET) system: a cluster-randomised controlled trial
Introduction
Unexpected deaths and cardiac arrests that occur in hospitals1, 2, 3 are often preceded by warning signs.4, 5 Similarly, unplanned admissions to intensive care units (ICU) are commonly foretold by abnormalities in patients' vital signs without appropriate action being undertaken.6, 7 These findings suggest that some of these adverse outcomes might be preventable.
A hospital-wide approach to the management of patients at risk of unexpected deaths and cardiac arrests, by early recognition of deterioration and early resuscitation, has been developed to reduce the number of unexpected deaths, cardiac arrests, and unplanned ICU admissions.8 This approach is based on the medical emergency team (MET) system, which includes staff education, the introduction of MET calling criteria, increased awareness of the dangers of physiological instability, and immediate availability of a MET. The MET quickly responds to abnormalities in patients' vital signs, specific conditions, and staff concerns in much the same way as a cardiac arrest team would, but at an earlier stage of physiological instability.
The rationale behind this approach is that early intervention in response to physiological instability might prevent further deterioration in many patients. In studies that have had restricted analysis (by being small, using historical controls, or using unrandomised comparisons), operation of a MET system has been associated with a reduction in unplanned ICU admissions,9 cardiac arrests, and deaths.10, 11, 12 To rigorously assess the MET system, we undertook a cluster-randomised controlled trial in 23 hospitals in Australia and investigated the effectiveness of the system in hospitals of various sizes and organisational characteristics.
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Participating hospitals and procedures
We identified potential participating hospitals using the Australian Hospital and Health Services Yearbook.13 Public hospitals with more than 20 000 estimated admissions every year, with an ICU and emergency department, and that did not already have a MET, were eligible for participation. The director of the ICU or emergency department was contacted and invited to participate. Approval to participate was obtained from all the hospitals' human research ethics committees.
Outcome and process
Results
23 hospitals were randomised to receive introduction of a MET system or to be controls (figure). Hospital and patient characteristics in the MET and control hospitals were similar during the baseline period; they were also comparable with respect to the baseline period incidence of primary and secondary outcomes (table 1).
During the study period, the overall rate of calls for the cardiac arrest team or MET was significantly higher in intervention hospitals than in control hospitals (p=0·0001;
Discussion
We undertook a cluster-randomised controlled trial to study the effects of the introduction of a MET system on the composite incidence of unexpected deaths, cardiac arrests, and unplanned ICU admissions. Introduction of such a system did not significantly reduce the incidence of our study outcomes. Possible explanations for our findings are that the MET system is an ineffective intervention; the MET is potentially effective but was inadequately implemented in our study; we studied the wrong
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