Evaluation of the performance of the GRACE risk score in predicting long-term mortality in Tunisian patient presenting with non-ST-elevation acute coronary syndrome

Abstract

The Global Registry of Acute Coronary Events (GRACE) risk score is recommended in international guidelines for the risk stratification of non-ST-elevation acute coronary syndome (NSTE-ACS) for in-hospital and 6-month mortality. There is currently no validated risk model to predict mortality beyond 6 months in Tunisian context. We aimed to evaluate the performance of the GRACE risk score in predicting in-hospital, 6-month, 1-year and 3-year mortality. In this retrospective single center cohort study, all consecutive patients admitted to our department for NSTE-ACS from April 2014 to July 2016 were enrolled. Follow-up at 6 months, 1 year and 3 years was reported. The GRACE risk score was calculated for all patients and its discriminative performance for mortality prediction evaluated by means of area under the receiver operating curve (AUC). A total of 340 patients were included. Mean age was 65.2 ± 12.7 years, 61.8% were male, prevalence of diabetes mellitus and hypertension was 57.3% and 65.9%, respectively. Upon admission, 57% of patients had positive troponin assay and 13.5% had a GRACE score > 140. An invasive strategy was adopted in 86.2% of our patients and revascularization was proposed for 71.2% of them. In-hospital, 1-year and 3-year mortality were 2.35%, 3.2%, 7.6% and 15.2%, respectively. The performance of the GRACE risk score was not good for in-hospital mortality (AUC = 0.681 95% CI: 0.55–0.82, P = 0.2) probably due to the low mortality rate. The model performed well in 6-month mortality (AUC = 0.879, 95% CI: 0.82–0.93, P < 0.001), in 12-month mortality (AUC = 0.853, 95% CI: 0.77–0.92, P < 0.001) and in 3-year mortality (AUC = 0.879, 95% CI: 0.83–0.92, P < 0.001). In our context, the GRACE postdischarge risk score accurately discriminate mortality over the longer term (up to 3 years) in all subsets of NSTE-ACS patients, and thus may be used in our practice.