Abstract 18536: Performance of Framingham Risk Function With Coronary Artery Calcium in Predicting Major Coronary Events in an Asian Cohort

Abstract

Background: In non-White populations, the original Framingham risk functions (FRF) overestimates coronary heart disease (CHD) risk and requires recalibration. We tested whether the inclusion of coronary artery calcium (CAC) can improve the performance of the FRF in CHD prediction in an asymptomatic Asian cohort. Methods: We determined risk factors, CAC burden and CV outcomes in a sample of 4502 asymptomatic South Koreans (from the registry-based ESCORT Study) and in 3141 asymptomatic Caucasian participants from the Framingham Heart Study (FHS). Primary endpoint was a composite of cardiovascular death, myocardial infarction, and unstable angina with revascularization. We assessed both the discriminatory value of the original FRF before and after the addition of CAC using area under the receiver operator characteristic (AUC) and the calibration/predictive ability using the D’Agostino-Nam Chi squared test for survival data, where a chi-square statistic > 20 indicates poor calibration. Results: There were 95 hard CHD events (45 ESCORT, 50 FHS) over a 55 month (ESCORT) and 60 month (FHS) follow-up period. For the FRF, the AUROC was 0.82, and the D’Agostino-Nam chi-squared statistic was 22.59 (p = 0.007) for predicting MACE in the ESCORT cohort. After the addition of CAC, the AUC improved to 0.85 and the D’Agostino-Nam chi-squared statistic improved to 16.14 (p = 0.064). The Caucasian-derived FRF model had poor predictive ability/calibration and consistently overestimated event rates in the Asian ESCORT cohort over all risk categories. For instance, in the 10th decile of risk, the predicted event rate using the FRF was 6% compared to an actual rate of 3.5% in the ESCORT cohort (Figure 1a) Conclusion: Addition of CAC to the classic Framingham risk functions significantly improves its performance in terms of discrimination and calibration in the prediction of major adverse CHD events in an Asian (South Korean) population.