[The performance of intensive care services]

To evaluate the performance of intensive care unit (ICU) the severity scores are measured on the first day; organ system dysfunctions are measured several times during the stay. The severity scores are developed from large data bases of thousands of patients. They include the patient age, previous health status, severity and sometimes the main diagnosis. Prediction models are published to evaluate the risk of death for each patient. By adding the risk of death of each patient and dividing by the number of patients, the expected mortality rate is calculated. By comparing the observed and expected mortality rates the Standard Mortality Ratio (SMR) may be measured. The data collection must be rigorous, the studied population must be similar to the population of the large data bases. Other elements of performance may be evaluated, such as the cost-efficiency or the quality of life or surviving patients.