The ACEF II Risk Score for Cardiac Surgery
What is the discriminative ability of the updated version of the age, creatinine, and ejection fraction score (ACEF II) inclusive of emergency surgery and preoperative anemia?
The development series for this study included 7,011 consecutive cardiac surgery patients operated at a single institution. The validation series included 1,687 consecutive cardiac surgery patients operated in a different institution. The five factors included in the ACEF II were assessed in a multivariable logistic regression model testing their independent role as predictors of operative (in hospital or 30 days after surgery) mortality. Based on the odds ratio of each predictor, the ACEF II score is calculated as age (years)/ejection fraction (%). Additional points are attributed to a serum creatinine level >2 mg/dl (2 points), emergency surgery (3 points), and anemia (hematocrit [HCT] <36%, 0.2 points per each HCT point below 36%). The final model was well calibrated.
Discrimination of the ACEF II (c-statistics 0.814) was significantly (p = 0.041) better than the ACEF (c-statistics 0.773) and equal to the EuroSCORE II. In the external validation, the ACEF II confirmed a better discrimination than the ACEF and had good calibration properties.
The authors concluded that the ACEF II score allows the inclusion of emergency patients and, appears more adequate to the present cardiac surgery scenario.
This study reports that the ACEF II score presents itself as parsimonious, more comprehensive, and updated tool for operative mortality risk stratification in contemporary cardiac surgery, but needs additional external validation. Anemia is a modifiable risk factor, and iron supplementation has been recommended, even if still unproven, for the treatment of anemic patients undergoing cardiac surgery. Furthermore, the ACEF II may be a useful tool to stratify the operative risk with and without anemia correction and verify the efficacy of this approach including anemia correction.
Keywords: Anemia, Calibration, Cardiac Surgical Procedures, Creatinine, Hematocrit, Primary Prevention, Risk Factors
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