Analysis of the Performance of Daily Cardiac Surgery Score (CASUS) in Patients with Mixed Racial Profile after Cardiac Surgery: A Single-Center Retrospective Study

Abstract

Objective: The aim was to look at the Cardiac Surgery Score (CASUS) assessment after cardiac surgery, and compare it with the intensive care unit (ICU) mortality and morbidity, in a racially diverse group of patients, in a single center. Design: Clinical retrospective study analyzing data from 319 patients over a 1-year duration. Setting: Cardiothoracic intensive care unit (CTICU) of a tertiary care center. Participants: All patients who underwent cardiac surgery between January 1 and December 31, 2017. Interventions: Review of electronic patient records. Measurements and Results: Daily CASUS assessments (calculated on an online application and recorded on patient electronic records) were retrieved. The variables of CASUS used for the study were CASUS value on postoperative day 1 (POD1-CASUS), on death/discharge from CTICU (Dis-CASUS), mean of all CASUS values during CTICU stay (M-CASUS), and differential CASUS (Dif- CASUS) [CASUS POD 1 – CASUS on discharge]. The receiver operating characteristic (ROC) curve for the diagnostic level of POD 1-CASUS, indicating mortality, was calculated. A value of >6.5 for POD 1 CASUS had 80% sensitivity and 84% specificity, with area under the curve value 0.756 (95% confidence interval: 0.46 to 1). The mean values of POD1-CASUS (8.6 ± 6), M-CASUS (8.2 ± 5.2), and Dis-CASUS (7.8 ± 5.7) were significantly higher in cases of mortality, compared to the others. POD1-CASUS, M-CASUS, and Dis-CASUS were found to be statistically significantly elevated in patients with acute kidney injury (AKI) and postoperative stroke, and in those who were readmitted to the CTICU after initial discharge. Patients with POD1-CASUS ≥6.5 had a statistically significant association with mortality and postoperative morbidity (p < 0.05). Findings from multivariate logistic regression indicated that body mass index (BMI), ICU readmission, length of mechanical ventilation, and length of ICU stay remained associated significantly with POD1 CASUS ≥6.5. Conclusion: This study found that CASUS on POD 1, mean values of CASUS during CTICU stay, and CASUS at death/discharge from CTICU predicted ICU mortality after cardiac surgery in this racially diverse group. The CASUS derivatives can be used to predict unfavorable outcomes after cardiac surgery. A POD1-CASUS value of 6.5 or more could signify mortality and postoperative morbidity.