EuroSCORE II

Overview

EuroSCORE II replaced the original additive and logistic EuroSCORE (1999) as the recommended preoperative risk model for adult cardiac surgery in Europe, after the older model was shown to substantially overestimate mortality in the mostly low-risk contemporary surgical population ^[2]. It uses a fully logistic regression model, yielding a predicted 30-day in-hospital mortality as a probability rather than a risk category. The model was derived from 22,381 consecutive patients undergoing cardiac surgery in 43 countries between May 2010 and July 2011 ^[1].

Two variables in the model have counter-intuitive definitions worth knowing before entering data: age is not used as a raw continuous value — every age of 60 or below contributes the same fixed amount of risk, and each year above 60 adds one further increment — and renal function is graded by creatinine clearance (Cockcroft-Gault, which factors in weight and sex), not by a simple serum creatinine cutoff as in the original 1999 EuroSCORE.

Formula

logit = −5.324537 + Σ (variable coefficients)

Predicted mortality = e^logit / (1 + e^logit)

Age contributes as Xi = 1 for any age ≤ 60, or Xi = age − 59 for age > 60, multiplied by the age coefficient below — so a 45-year-old and a 60-year-old receive an identical age contribution, while a 75-year-old receives 15 increments.

Patient Factors

Variable	Coefficient (β)
Age (Xi transform, see above)	0.0285181
Female sex	0.2196434
Renal function — CrCl 51–85 mL/min	0.303553
Renal function — CrCl ≤ 50 mL/min	0.8592256
Renal function — on dialysis	0.6421508
Extracardiac arteriopathy	0.5360268
Poor mobility	0.2407181
Previous cardiac surgery	1.118599
COPD (long-term bronchodilator/steroid use)	0.1886564
Active endocarditis	0.6194522
Critical preoperative state	1.086517
Insulin-dependent diabetes mellitus	0.3542749

Cardiac & Operation Factors

Variable	Category	Coefficient (β)
NYHA class	II	0.1070545
	III	0.2958358
	IV	0.5597929
CCS angina class 4	Yes	0.2226147
LV function (EF)	Moderate 31–50 %	0.3150652
	Poor 21–30 %	0.8084096
	Very poor ≤ 20 %	0.9346919
Recent MI (≤ 90 days)	Yes	0.1528943
Pulmonary hypertension	Moderate 31–55 mmHg	0.1788899
	Severe > 55 mmHg	0.3491475
Urgency	Urgent	0.3174673
	Emergency	0.7039121
	Salvage	1.362947
Weight of procedure	Two procedures	0.5521478
	Three or more	0.9724533
Surgery on thoracic aorta	Yes	0.6527205

Risk Classification

Predicted Mortality	Risk Class
< 2 %	Low
2–5 %	Moderate
5–10 %	High
> 10 %	Very high

These bands are a Scores2Go convention for quick triage, not a classification defined in the original paper — EuroSCORE II itself reports only a continuous predicted-mortality percentage.

Scientific Validity & Limitations

External validations have generally confirmed good discrimination for EuroSCORE II, but — as with most severity scores fit to a specific era and population — calibration varies by cohort. A 2013 validation in a modern UK cardiac surgery cohort found strong discrimination alongside some miscalibration by risk stratum ^[3]. A larger multicentre comparison the same year found EuroSCORE II calibrated substantially better than either the additive or logistic versions of the original 1999 EuroSCORE, though non-trivial overestimation persisted in some risk strata ^[4]. A 2014 meta-analysis pooling 22 validation studies and more than 145,000 procedures confirmed consistently good discrimination overall, but substantial between-study heterogeneity in calibration — observed-to-expected mortality ratios varied meaningfully by country, era, and case-mix ^[5].

Well-documented limitations, independent of any single validation study:

• Renal variable is easy to miscode: the model requires creatinine clearance (Cockcroft-Gault, which needs weight, age, and sex), not a raw serum creatinine value — using serum creatinine directly, as some non-standard calculators have done, systematically misclassifies patients.
• Counter-intuitive age handling: the model assigns identical age-related risk to all patients aged 60 or younger; clinicians unfamiliar with this transform may expect age to behave as a smooth continuous risk factor throughout the full age range.
• No condition-specific endpoints: a head-to-head comparison with the Society of Thoracic Surgeons (STS) risk model found similar discrimination for mortality, but STS additionally reports stroke, renal failure, and prolonged ventilation risk — EuroSCORE II predicts operative mortality only ^[6].
• Subjective urgency categories: the boundary between "urgent," "emergency," and "salvage" surgery can be judged differently between centres, and this categorical variable carries some of the largest coefficients in the model.
• Not validated for individual treatment decisions: like other cardiac-surgery risk models, EuroSCORE II is intended to support Heart Team discussion and population-level quality benchmarking, not to determine operability for a single patient on its own.

Literature

1. Nashef SA, Roques F, Sharples LD, Nilsson J, Smith C, Goldstone AR, Lockowandt U. EuroSCORE II. Eur J Cardiothorac Surg. 2012;41(4):734–744. doi:10.1093/ejcts/ezs043
2. Nashef SA, Roques F, Michel P, Gauducheau E, Lemeshow S, Salamon R. European system for cardiac operative risk evaluation (EuroSCORE). Eur J Cardiothorac Surg. 1999;16(1):9–13. doi:10.1016/s1010-7940(99)00134-7
3. Chalmers J, Pullan M, Fabri B, et al. Validation of EuroSCORE II in a modern cohort of patients undergoing cardiac surgery. Eur J Cardiothorac Surg. 2013;43(4):688–694. doi:10.1093/ejcts/ezs406
4. Barili F, Pacini D, Capo A, et al. Does EuroSCORE II perform better than its original versions? A multicentre validation study. Eur Heart J. 2013;34(1):22–29. doi:10.1093/eurheartj/ehs342
5. Guida P, Mastro F, Scrascia G, et al. Performance of the European System for Cardiac Operative Risk Evaluation II: a meta-analysis of 22 studies involving 145,592 cardiac surgery procedures. J Thorac Cardiovasc Surg. 2014;148(6):3049–3057. doi:10.1016/j.jtcvs.2014.07.039
6. Kirmani BH, Mazhar K, Fabri BM, Pullan DM. Comparison of the EuroSCORE II and Society of Thoracic Surgeons 2008 risk tools. Eur J Cardiothorac Surg. 2013;44(6):999–1005. doi:10.1093/ejcts/ezt216