BACKGROUND - Coronary artery calcium (CAC) is a powerful novel risk indicator for atherosclerotic cardiovascular disease (ASCVD). Currently, there is no available ASCVD risk prediction tool that integrates traditional risk factors and CAC.
METHODS - To develop a CAC ASCVD risk tool for younger individuals in the general population, subjects aged 40-65 without prior CVD from three population-based cohorts were included. Cox proportional hazards models were developed incorporating age, sex, systolic blood pressure, total and HDL cholesterol, smoking, diabetes, hypertension treatment, family history of MI, high-sensitivity CRP (hs-CRP), and CAC scores (Astro-CHARM model) as dependent variables and ASCVD (non-fatal/fatal MI or stroke) as the outcome. Model performance was assessed internally, and validated externally in a fourth cohort.
RESULTS - The derivation study comprised 7382 individuals with mean age 51 years, 45% female, and 55% non-white. The median CAC was 0 (25-75th [0,9]) and 304 ASCVD events occurred in median 10.9 years of follow-up. The c-statistic was 0.784 for the risk factor model, and 0.817 for Astro-CHARM (p<0.0001). Compared with the risk factor model, the Astro-CHARM model resulted in integrated discrimination improvement (IDI=0.0252) as well as net reclassification improvement (NRI=0.121, p<0.0001). The Astro-CHARM model demonstrated good discrimination (c=0.78) and calibration (Nam-D’Agostino χ2:13.2, p=0.16) in the validation cohort (n=2057; 55 events). A mobile application and web-based tool were developed to facilitate clinical application of this tool ( www.AstroCHARM.org).
CONCLUSIONS - The Astro-CHARM tool is the first integrated ASCVD risk calculator to incorporate risk factors, including hs-CRP and family history, and CAC data. It improves risk prediction compared with traditional risk factor equations and could be useful in risk-based decision making for CV disease prevention in the middle-aged general population.
