Outcome description and prediction of mortality in ICU cardiac surgical patients

Aims: The purpose of this study was to develop a specific postoperative score in intensive care unit (ICU) cardiac surgical patients for assessment of organ dysfunction and survival.

Methods: This prospective study consisted of all consecutive adult patients admitted after cardiac surgery to our ICU over a period of 5.5 years. Evaluation of variables was performed using the first year patients who stayed in ICU for at least 24 hours. The reproducibility was then tested in two validation sets using all patients. Performance was assessed with the Hosmer-Lemeshow (HL) goodness-of-fit test and receiver operating characteristic (ROC) curves and compared with the APACHE II and MODS.

Results: A total of 6007 patients were admitted to the ICU after cardiac surgery. Mean HL-values for the new score were 5.8 (APACHE II, 11.3; MODS, 9.7) for the construction set, 7.2 (APACHE II, 8.0; MODS, 4.5) for the validation set I and 4.9 for the validation set II. The mean area under the ROC curve was 0.91 (APACHE II, 0.86; MODS, 0.84) for the new score in the construction set, 0.88 (APACHE II, 0.84; MODS, 0.84) in the validation set I and 0.92 in the validation set II.

Conclusion: Our new ten-variable risk index performs very well, with calibration and discrimination very high, better than general severity systems, and it is an appropriate tool for daily risk stratification in ICU cardiac surgery patients. Thus, it may serve as an Expert System for diagnosing organ failure and predicting mortality in ICU cardiac surgical patients.