Validation of a novel risk score to predict mortality after surgery for acute type A dissection

OBJECTIVES The aim of this study was to externally validate a lab-based risk score (lactate, creatinine, aspartate aminotransferase, alanine aminotransferase or bilirubin) by Ghoreishi et al. to predict perioperative mortality in patients undergoing surgical repair for acute type A aortic dissection. METHODS The risk score to predict operative mortality was applied to a large and homogenous validation cohort that consisted of 632 patients undergoing surgery for acute type A aortic dissection in 2 centres. Multivariable regression analysis was performed to determine the impact on survival. Receiver operating characteristics with deduced area under the curve were used to assess the ability to predict perioperative mortality. RESULTS A total of 632 patients (54% male, mean age 62 +/- 14 years) were assigned to 3 different risk groups according to the calculated mortality score [low risk <7 (31.2%), moderate risk 7-20 (36.1%) and high >20 (32.7%)]. Perioperative mortality was 8% in the low-risk group, 10% in the moderate-risk group and 24% in the high-risk group (P < 0.0001). Receiver operating characteristic analysis of this new score revealed an area under the curve of 0.69 with adequate calibration. In addition, multivariable analysis revealed an independet assocation with perioperative mortality (odds ratio 1.509; 95% confidence interval 1.042-2.185). While overall survival differed between the risk groups (P < 0.0001), the score does not serve as an independent predictor of long-term mortality when adjusted for relevant covariates. CONCLUSIONS The external validation process confirmed that a newly proposed risk score offers clinicians a helpful and reliable tool to improve the preoperative risk assessment of acute type A aortic dissection patients based on easily accessible and broadly available laboratory parameters.