Addition of B-type natriuretic peptide to the GRACE score to predict outcome in acute coronary syndrome: a retrospective (development) and prospective (validation) cohort-based study

AIMS: The present study was designed to build and validate a composite score based on the Global Registry of Acute Coronary Events (GRACE) score and B-type natriuretic peptide (BNP) concentrations to predict outcome in patients with acute coronary syndromes (ACS). METHODS: The GRACE risk score and BNP concentrations were obtained in a retrospective and a prospective cohort. A composite score including the GRACE score and BNP concentrations was first developed in a retrospective cohort of 248 patients with ACS and then validated in a prospective cohort of 575 patients. The primary outcome was 6-month death or myocardial infarction. RESULTS: End points were reached in 34 patients in the retrospective cohort and in 68 patients in the prospective cohort. Both higher BNP concentration and GRACE score were independently associated with outcome in the retrospective cohort (p=0.003 and p<0.0001). The composite score could be obtained as follows: GRACE+BNP/60. The use of the composite score increased the accuracy of the GRACE score, with an increase in the C statistic from 0.810 (0.727 to 0.892) to 0.822 (0.745 to 0.902) in the retrospective cohort and from 0.724 (0.657 to 0.791) to 0.750 (0.686 to 0.813) in the prospective cohort. Finally, 7% of patients in the prospective study population were reclassified from low to high risk or from high to low risk using this composite score. CONCLUSIONS: Plasma BNP levels refine the accuracy of the GRACE score. A comprehensive risk score, which includes BNP concentration and the GRACE risk score, might improve ACS risk stratification in clinical practice.