Ethnicity-dependent performance of the Global Registry of Acute Coronary Events risk score for prediction of non-ST-segment elevation myocardial infarction in-hospital mortality: nationwide cohort study

Aims: The Global Registry of Acute Coronary Events (GRACE) score was developed to evaluate risk in patients with the acute coronary syndrome with or without ST-segment elevation. Little is known about its performance at predicting in-hospital mortality for ethnic minority patients. Methods and results: We identified 326 160 admissions with non-ST-segment elevation myocardial infarction (NSTEMI) in the Myocardial Infarction National Audit Project (MINAP), 2010-17, including White (n = 299 184) and ethnic minorities (excluding White minorities) (n = 26 976). We calculated the GRACE score for in-hospital mortality and assessed ethnic group baseline characteristics by low, intermediate and high risk. The performance of the GRACE risk score was estimated by discrimination [area under the receiver operating characteristic curve (AUC)] and calibration (calibration plots). Ethnic minorities presented younger and had increased prevalence of cardiometabolic risk factors in all GRACE risk groups. The GRACE risk score for White [AUC 0.87, 95% confidence interval (CI) 0.86-0.87] and ethnic minority (AUC 0.87, 95% CI 0.86-0.88) patients had good discrimination. However, whilst the GRACE risk model was well calibrated in White patients (expected to observed (E: O) in-hospital death rate ratio 0.99; slope 1.00), it overestimated risk in ethnic minority patients (E: O ratio 1.29; slope: 0.94). Conclusion: The GRACE risk score provided good discrimination overall for in-hospital mortality, but was not well calibrated and overestimated risk for ethnic minorities with NSTEMI.