Comparative validation of the GRACE 2.0 and EUROSCORE II for 6-month mortality risk estimation of patients with acute coronary syndrome undergoing urgent bypass graft surgery

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): The research was supported by the Ministry of Innovation and Technology NRDI Office within the framework of the Artificial Intelligence National Laboratory Program.

According to the current NSTE-ACS guidelines, the GRACE 2.0 score is used for predicting mortality risk of patients with acute coronary syndrome regardless of treatment modality. However, mortality risk of patients requiring acute bypass graft surgery is usually assessed by the EUROSCORE II model.

We aimed to validate comparatively the predictive ability of the two models in NSTE-ACS patients undergoing urgent bypass surgery.

We analysed data of 99 complete cases of an unicentre registry who underwent acute CABG surgery between 2013 and 2021. Patients were followed-up by means of hospital records, follow-up visits, and records of the National Health Insurance Fund. Besides analysis of the bootstrapped c-statistics, we constructed univariate Cox regression models and compared model fit using Fine’s partial likelihood ratio test for non-nested models. Statistical analysis was performed using R.

Of the ninety-nine cases, two patients were lost to follow-up at 180 days (2.02%). The mortality rate was 16/97 (16.49%) with a c-statistic of 0.82 (95% CI: 0.70 to 0.92) and 0.72 (95% CI: 0.57 to 0.86) for the GRACE 2.0 and EUROSCORE II models, respectively (p=0.11). Analysis of the fitted univariate Cox models revealed that the two models are highly ‘distinguishable’ (p=0.0004, variance test). Yet, with this small sample size, the difference in model fit did not reach statistical significance in the non-nested partial likelihood ratio test (p=0.08, that GRACE 2.0 fits better than EUROSCORE II).

The GRACE 2.0 score may have a good predictive power to estimate 180-day mortality risk of acute coronary syndrome patients undergoing acute bypass surgery. Our preliminary data may raise the possibility that it also may outperform the EUROSCORE II. Nevertheless, to test this hypothesis with adequate statistical power, larger, preferably multicentre data are needed.