[Use of mortality probability models (MPM II) in the evaluation of the effectiveness of care of critically ill patients. European and North American Study of Severity Systems].

BACKGROUND

The performance of the Mortality Probability Models (MPM II) has been assessed in Intensive Care Units (ICUs) in Catalonia and the Balearic Islands. The MPM II system has been customized to that geographic area and quality performance has been evaluated in each ICU.

METHODS

1,270 adult critical patients, consecutively admitted in 16 ICUs from Catalonia and 1 from the Balearic Islands have been included. Probability of dying in the hospital has been calculated at admission in the ICU and at 24 hours using the models MPM II0 and MPM II24. Goodness-of-fit of the MPM II system in the overall group of 17 ICUs has been analyzed. Logistic regression has been used to customize the MPM II system to all the ICUs together. A Quality Performance Index (QPI) for each ICU has been obtained by dividing the number of the observed deaths by the number of deaths expected by the MPM II system.

RESULTS

The overall QPI was 1.15 when using the MPM II0 and 1.17 when using the MPM II24. The QPI in the 17 ICUs ranged from 0.58 to 2.05. Three ICUs showed excess of mortality and 2 ICUs had less deaths than expected. The process of customization of MPM II to the 17 ICUs as a group improved the estimation of expected mortality.

CONCLUSIONS

The use of severity indexes allows to compare the outcome of patients in the ICU and provides an indicator of quality of care. The excess of mortality observed in some ICU should produce a watchful follow-up of outcome. Risk factors for excess of mortality should be studied.