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

Abstract

Abstract 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. Key question Does the performance of the Global Registry of Acute Coronary Events (GRACE) (v2.0) score in predicting in-hospital mortality for non-ST-segment elevation myocardial infarction (NSTEMI) differ by ethnicity? Key finding The GRACE risk score provided good discrimination overall for in-hospital mortality but was not well calibrated and overestimated risk for ethnic minority patients with NSTEMI. Take-home message Ethnicity or race should be considered during the development of risk scoring systems. Existing systems can be recalibrated in the population they serve to better address risk.