OBJECTIVES:

To determine whether earlier clinical intervention by a medical emergency team prompted by clinical instability in a patient could reduce the incidence of and mortality from unexpected cardiac arrest in hospital.

DESIGN:

A non-randomised, population based study before (1996) and after (1999) introduction of the medical emergency team.

SETTING:

300 bed tertiary referral teaching hospital.

PARTICIPANTS:

All patients admitted to the hospital in 1996 (n=19 317) and 1999 (n=22 847).

INTERVENTIONS:

Medical emergency team (two doctors and one senior intensive care nurse) attended clinically unstable patients immediately with resuscitation drugs, fluid, and equipment. Response activated by the bedside nurse or doctor according to predefined criteria.

MAIN OUTCOME MEASURES:

Incidence and outcome of unexpected cardiac arrest.

RESULTS:

The incidence of unexpected cardiac arrest was 3.77 per 1000 hospital admissions (73 cases) in 1996 (before intervention) and 2.05 per 1000 admissions (47 cases) in 1999 (after intervention), with mortality being 77% (56 patients) and 55% (26 patients), respectively. After adjustment for case mix the intervention was associated with a 50% reduction in the incidence of unexpected cardiac arrest (odds ratio 0.50, 95% confidence interval 0.35 to 0.73).

CONCLUSIONS:

In clinically unstable inpatients early intervention by a medical emergency team significantly reduces the incidence of and mortality from unexpected cardiac arrest in hospital.