The prospective validation of EuroSCORE II risk scoring system for patients underwent cardiac surgery: brief report

Background: Various prediction models have been developed aiming to estimate risk-adjusted mortality, morbidity and length of intensive care unit stay following cardiac surgeries. The European system for cardiac operative risk evaluation II (EuroSCORE II) is a prediction model which maps 18 predictors to a 30-day post-operative risk of death. The objective of this study was to evaluate the performance of the EuroSCORE II risk-analysis predictions among patients who underwent heart surgeries. Methods: A prospective cross-sectional study was conducted to collect required variables for all consecutive patients underwent heart surgeries in Emam Reza hospital, Mashhad, Iran, from March 2014 to March 2015. Once the patient was hospitalized a cardiologist or a general physician evaluated pre- peri- and post-operative state to fill out the pre-designed structural paper form. Comparing the observed and expected mortality, the sensitivity, specificity, area under the receiver operating characteristic curve (AUC) and finally the discrimination power of the model for our patients were calculated and reported. The model value was calculated using the online tool. Results: A total of 1337 patients (60% males) were included, the observed mortality rate was 3.2%. Although the overall performance was acceptable, the model showed poor discriminatory power (AUC=0.667, CI 95%: 0.648-0.685) and accuracy with sensitivity=61.88% and specificity=66.23%. Conclusion: Our single-center study, based on consecutive patients who underwent cardiac surgery showed that EuroSCORE II demonstrated a moderate statistical overall performance with poor discrimination and calibration measures remain as concerning issues regarding 30-day post-operative mortality prediction after adult cardiac surgery. Poor performance measures for this system show the need for reformulating this risk stratification tool aiming to improve post cardiac surgery outcome predictions in Iran.