Recalibration of the Global Registry of Acute Coronary Events risk score in a multiethnic Asian population

Background: Acute myocardial infarction (AMI) is a leading cause of mortality in Asia. However, quantitative risk scores to predict mortality after AMI were developed without the participation of Asian countries.

Methods: We evaluated the performance of the Global Registry of Acute Coronary Events (GRACE) in-hospital mortality risk score, directly and after recalibration, in a large Singaporean cohort representing 3 major Asian ethnicities.

Results: The GRACE cohort included 11,389 patients, predominantly of European descent, hospitalized for AMI or unstable angina from 2002 to 2003. The Singapore cohort included 10,100 Chinese, 3,005 Malay, and 2,046 Indian patients hospitalized for AMI from 2002 to 2005.Using the original GRACE score, predicted in-hospital mortality was 2.4% (Chinese), 2.0% (Malay), and 1.6% (Indian). However, observed in-hospital mortality was much greater at 9.8% (Chinese), 7.6% (Malay), and 6.4% (Indian). The c statistic for Chinese, Malays, and Indians was 0.86, 0.86, and 0.84, respectively, and the Hosmer-Lemeshow statistic was 250, 56, and 41, respectively. Recalibration of the GRACE score, using the mean-centered constants derived from the Singapore cohort, did not change the c statistic but substantially improved the Hosmer-Lemeshow statistic to 90, 24, and 18, respectively. The recalibrated GRACE score predicted in-hospital mortality as follows: 7.7% (Chinese), 6.0% (Malay), and 5.2% (Indian).

Conclusion: In this large cohort of 3 major Asian ethnicities, the original GRACE score, derived from populations outside Asia, underestimated in-hospital mortality after AMI. Recalibration improved risk estimation substantially and may help adapt externally developed risk scores for local practice.