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Effects of a medical emergency team on reduction of incidence of and mortality from unexpected cardiac arrests in hospital: preliminary study

BMJ 2002; 324 doi: https://doi.org/10.1136/bmj.324.7334.387 (Published 16 February 2002) Cite this as: BMJ 2002;324:387

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No proof that METs reduce incidence of and mortality from in-hospital cardiac

To the editor:

Proof that a medical emergency team (MET) can reduce the incidence of
and mortality from “unexpected” cardiac arrest is eagerly awaited, as such
a proposal is intuitive. However, the number of such arrests can be
influenced by several factors, including the number of “do not attempt
resuscitation” (DNAR) decisions made. The article by Buist et al [1] fails
to take this into account and the study suffers from other method errors.
The work uses a historical control group and was undertaken in a setting
in which there was already a trend towards reduced incidence and mortality
from cardiac arrest. The case mix varied considerably between the two
study periods, with greater numbers of planned admissions – a group with
a low risk of cardiac arrest – in 1999. The authors’ definition of cardiac
arrest included patients who had not actually experienced an arrest, yet
excluded 4 patients with a DNAR status for whom a call was initiated. Ward
patients who do not actually arrest have a better outcome than those who
do; hence by adopting a loose definition, the study denominator has been
artificially enhanced giving a false benefit.

There is acceptance that some patients receive cardiopulmonary
resuscitation despite it being futile, hence the need to establish the
resuscitation status of critically ill patients. However, any increase in
DNAR orders has the inevitable effect of reducing the incidence of and
mortality from “unexpected” cardiac arrests. The introduction of a MET has
already been shown to increase the number of DNAR orders [2]. Buist et al
report that, in 1999, the MET made 13 DNAR orders for patients who
subsequently died, but do not report the overall hospital DNAR rate in
either year.

The design of the study makes it impossible to separate the
beneficial impact of the formal education process provided to ward staff
from that due to specific MET interventions. It is possible that this
education may have led to better ward care or to a greater number of DNAR
orders being applied by non-MET staff. Perhaps education alone may have
resulted in the results that are currently being attributed to the MET.

The BMJ cover suggests that Buist et al have confirmed a beneficial
role for the MET. This may be correct, as the MET may have reduced the
number of inappropriate cardiac arrest calls by increasing the incidence
of DNAR orders or by improving the education of ward staff. What is not
proven is that a MET can reduce the incidence and mortality from
unexpected cardiac arrest.

References

1. Buist MD, Moore GE, Bernard SA, Waxman BP, Anderson JN, Nguyen TV.
Effects of a medical emergency team on reduction of incidence of and
mortality from unexpected cardiac arrests in hospital: preliminary study.
BMJ 2001; 324: 1-6.

2. M.J.A. Parr, J.H. Hadfield, A. Flabouris, G. Bishop, K. Hillman. The
Medical Emergency Team: 12 month analysis of reasons for activation,
immediate outcome and not-for-resuscitation orders. Resuscitation 2001;
50: 39 – 44.

Competing interests: No competing interests

02 March 2002
Gary B Smith
Consultant in Intensive Care Medicine
Jerry Nolan, Consultant in Anaesthesia and Intensive Care, Royal United Hospital, Bath BA1 3NG
Portsmouth Hospitals NHS Trust, Cosham, Portsmouth, PO6 3LY