The ROC curves of the GRACE risk score and its combination with admission serum calcium in (A) overall participants and subgroups of patients with (B) STEMI or (C) UA/NSTEMI. Abbreviations: AUC, area under the curve; GRACE, Global Registry of Acute Coronary Events; IDI, integrated discrimination improvement; NRI, net reclassification improvement; NSTEMI, non–ST‐segment elevation myocardial infarction; ROC, receiver operating characteristic; UA, unstable angina.