Scoring Systems for Outcome Prediction in a Cardiac Surgical Intensive Care Unit: A Comparative Study

Abstract

Background: Most scoring systems used to predict clinical outcome in critical care were not designed for application in cardiac surgery patients.

Objectives: To compare the predictive ability of the most widely used scoring systems (Acute Physiology and Chronic Health Evaluation [APACHE] II, Simplified Acute Physiology Score [SAPS] II, and Sequential Organ Failure Assessment [SOFA]) and of 2 specialized systems (European System for Cardiac Operative Risk Evaluation [EuroSCORE] II and the cardiac surgery score [CASUS]) for clinical outcome in patients after cardiac surgery.

Methods: Consecutive patients admitted to a cardiac surgical intensive care unit (CSICU) were prospectively studied. Data on the preoperative condition, intraoperative parameters, and postoperative course were collected. EuroSCORE II, CASUS, and scores from 3 general severity-scoring systems (APACHE II, SAPS II, and SOFA) were calculated on the first postoperative day. Clinical outcome was defined as 30-day mortality and in-hospital morbidity.

Results: A total of 150 patients were included. Thirty-day mortality was 6%. CASUS was superior in outcome prediction, both in relation to discrimination (area under curve, 0.89) and calibration (Brier score = 0.043, χ(2) = 2.2, P = .89), followed by EuroSCORE II for 30-day mortality (area under curve, 0.87) and SOFA for morbidity (Spearman ρ= 0.37 and 0.35 for the CSICU length of stay and duration of mechanical ventilation, respectively; Wilcoxon W = 367.5, P = .03 for probability of readmission to CSICU).

Conclusions: CASUS can be recommended as the most reliable and beneficial option for benchmarking and risk stratification in cardiac surgery patients.