Prognostic Value of Daily Cardiac Surgery Score (CASUS) and its Derivatives in Cardiac Surgery Patients

Abstract

Background: We aimed to validate the usefulness of CASUS derivatives for cardiac surgery patients and their reliability for daily decision making. Methods: We included, prospectively, the data of all adult cardiac surgery patients who had an ICU stay of at least 12 hours between 20 January 2003 and 14 October 2005 in the Department of Cardiothoracic Surgery of the University of Cologne, Germany. Data were collected until ICU discharge and included initial, maximum, mean, and total CASUS values. δ CASUS (difference from initial value) was calculated at 48 and 96 hours postoperatively. The predictive efficacy of the derivatives was tested with calibration and discrimination statistics. Results: 2372 patients were included with a mean age of 66.2 ± 11.2 years. ICU mortality was 3.6 % (n = 85). Mean ICU stay was 3.0 ± 6.1 days. The discrimination was very good for all derivatives (area under the curve ranged between 0.988 and 0.926). The calibration was also good except for the total CASUS, which showed a significant difference between the expected and observed mortality. Increased δ CASUS at 48 hours (1038 patients) and 96 hours (435 patients) correlated with an increase in mortality (23.1 % and 42.9 %, respectively), and conversely a decreased mortality rate was observed with decreasing values (1.9 % and 3.8 %, respectively). Conclusion: CASUS derivatives including δ CASUS have a good prognostic value for cardiac surgery patients with regard to the prediction of mortality and survival during ICU stay, with the exception of total CASUS which was not informative.