External Validation of Modified EuroSCORE

Background EuroSCORE is an adult cardiac surgery risk scoring method that is used worldwide, which has been shown to significantly overestimate the operative risk. We derived a new risk scoring method by modifying some of the risk factors included in the EuroSCORE algorithm and we validated it in an external database. Methods This study included 4,014 patients who underwent adult cardiac surgery at the Heart Centre, Tampere University Hospital, Finland. Operative risk was estimated by EuroSCORE and its modified version. Results In-hospital postoperative mortality rate was 3.2%. EuroSCORE (AUC for logistic EuroSCORE 0.82; 95% confidence interval (CI), 0.79–0.85) and modified score (AUC for logistic modified score 0.79; 95% CI, 0.75–0.83) performed well in predicting in-hospital mortality in this series. The mean logistic EuroSCORE was 8%, and the mean logistic modified score was 2.2%. Thus, the observed to expected ratio for in-hospital mortality was 0.4 for logistic EuroSCORE and 1.5 for logistic modified score. The difference between observed and predicted mortality rate matched correctly for increasing additive modified score, but not for EuroSCORE. The observed to predicted ratio in high-risk patients (within the 90th percentile of each risk algorithm) was 0.36 (13.2%/36.2% in 402 patients) for logistic EuroSCORE and 0.99 (14.7%/14.9% in 395 patients) for logistic modified score. Conclusions This modified and simplified score, which includes most of EuroSCORE variables, seems to provide a more realistic estimation of postoperative mortality risk of patients undergoing any adult cardiac surgery.