The European System for Cardiac Operative Risk Evaluation (EuroSCORE) is one of the most widely used cardiac risk models for predicting mortality after cardiac surgery and forms the basis of many pre-operative discussions surrounding risk/benefit ratios and gaining informed consent for a procedure.  First published in 1999 and derived from an international European database, the system has been highly successful, but with time and improvements in cardiothoracic techniques and mortality, it is now clear that model overpredicts risk and is no longer appropriately calibrated. In the EuroSCORE II project the aim was to update this system and make it more relevant to contemporary practice.

Using an online data collection system, prospective risk and outcome data on 22 381 patients undergoing major cardiac surgery in 154 hospitals in 43 countries was gathered.  Care was taken to recruit data from a wide variety of hospitals and not just centres of excellence to avoid ascertainment bias.  Information was obtained on a variety of patient elements beyond the traditional existing EuroSCORE risk factors with the primary outcome being mortality at the base hospital and secondary outcomes being mortality at 30 and 90 days.  Compared with the original EuroSCORE database (in brackets), the mean age was greater 64.7 (62.5) with 31% females (28%). Also, more patients were New York Heart Association class IV, had extracardiac arteriopathy and renal and pulmonary dysfunction.  Overall mortality was 3.9% (4.6%). When applied to the current data, the old risk models overpredicted mortality (actual: 3.9%; additive predicted: 5.8%; logistic predicted: 7.57%). Using logistic regression modelling to identify the most pertinent and predictive risk factors the new EuroSCORE II (http://euroscore.org/calc.html) was constructed and in  subsequent testing in a validation cohort of 5553 patients performed well (actual mortality: 4.18%; predicted: 3.95%) with well-maintained discrimination and an area under the receiver operating characteristic curve of 0.8095.

Conclusions

Cardiac surgical mortality has significantly reduced in the last 15 years despite older and sicker patients. EuroSCORE II is better calibrated than the original model and preserves powerful discrimination providing patients and surgeons with improved pre-operative risk prediction.

•  Nashef SA, Roques F, Sharples LD, Nilsson J, Smith C, Goldstone AR, Lockowandt U. EuroSCORE II. Eur J Cardiothorac Surg. 2012 Apr;41(4):734-45.