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[Learning from experience. Applications of control charts to the monitoring of performance in cardiology].

BACKGROUND
Health services and teams of professionals should be able to monitor the process and outcomes of the care provided, in order to assess and maintain quality. In this paper the application of the control chart technique as a tool for the evaluation of in-hospital mortality of patients with acute myocardial infarction is presented and discussed.


METHODS
The control chart technique, based on the comparison between the outcome observed and the one expected in each individual patient, taking into account prognostic factors, has been applied in the evaluation of in-hospital mortality of 193 patients cared for at four centers of one of the AUSL of Bologna, during the year 2000. Yearly case volume for each of the four centers ranged from 14 to 68 patients. Overall mortality was 8.8, 18.0, 18.0, and 28.6% in the four centers.


RESULTS
Use of control charts made it possible to identify relevant differences in outcomes among the four study centers, which would have been otherwise overlooked with usual statistical approaches. In particular, over the whole study period two centers showed relevant variations in their ability to achieve the desired clinical outcome.


CONCLUSIONS
Clinical teams may use control charts as a tool to monitor their performance and for a timely identification of aspects of care deserving further investigation and analysis.