The performance of EuroSCORE II in CABG patients in relation to sex, age, and surgical risk: a nationwide study in 14,118 patients

BACKGROUND: To determine the discriminative accuracy and calibration of EuroSCORE II in relation to age, sex, and surgical risk in a large nationwide coronary artery bypass grafting (CABG) cohort. METHODS: All 14,118 patients undergoing isolated CABG in Sweden during 2012–2017 were included. Individual patient data were taken from the SWEDEHEART registry. Patients were divided by age (< 60, 60–69, 70–79, ≥ 80 years), sex, and surgical risk (low: EuroSCORE < 4%, intermediate: 4–8%, high: > 8%). Discriminative accuracy was determined by the area under the receiver operating characteristic curve (AUC) and calibration by the observed/estimated (O/E) mortality ratio at 30 days. RESULTS: AUC and O/E ratio were 0.82 (95% CI 0.79–0.85) and 0.58 (0.50–0.66) overall, 0.82 (0.79–0.86) and 0.57 (0.48–0.66) in men, and 0.79 (0.73–0.85) and 0.60 (0.47–0.75) in women. Regarding age, discriminative accuracy was highest in patients aged 60–69 years (AUC: 0.86 [0.80–0.93]) but was satisfactory in all groups (AUC: 0.74–0.80). O/E ratio varied from 0.26 for patients > 60 years to 0.90 for patients > 80 years. Regarding surgical risk, AUC and O/E ratio were 0.63 (0.44–0.83) and 0.18 (0.09–0.30) in low-risk patients, 0.60 (0.55–0.66) and 0.57 (0.46–0.68) in intermediate-risk patients, and 0.78 (0.73–0.83) and 0.78 (0.64–0.92) in high-risk patients. CONCLUSIONS: EuroSCORE II had good discriminative accuracy independently of sex and age, but markedly overestimated mortality risk, especially in younger patients. Accuracy and calibration were better in high-risk patients than in low-risk and intermediate-risk patients. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s13019-023-02141-4.