Abstract 14328: Coronary Artery Calcium Reclassifies Risk in Younger Individuals: Results From the Dallas Heart Study
Background: Coronary artery calcium (CAC) has emerged as one of the most powerful novel predictors of coronary heart disease (CHD). Significant correct reclassification of risk has been demonstrated in a few population based studies comprised of older individuals. We sought to determine the magnitude of risk reclassification with CAC in a relatively young cohort and compare it with prior reports.
Methods: Subjects from the multiethnic, population based Dallas Heart Study ages 30-65 years underwent CAC scanning and were followed for the development of CHD (CHD death, MI, PCI or CABG). The contribution of CAC to a model comprised of Framingham risk score variables (FRS) was assessed using c-statistics and net reclassification improvement (NRI). CAC was primarily handled as a continuous variable (ln(CAC+1)).
Results: A total of 2390 participants were included, with mean age 45 (±9) years); 56% were women and 48% African American. After a mean follow up of 8 years 76 first CHD events occurred. In multivariable analysis, CAC was independently associated with CHD (HR per SD 1.8, 95% CI 1.41, 2.15; p<0.001). The addition of CAC to a FRS model increased the c-statistic from 0.84 to 0.88 (p=0.009). The NRI for the entire cohort was 15.8% (p=0.005). When restricted to intermediate risk subjects (10 year predicted CHD risk of 6-20%) the NRI was 20.4% (p=0.027). When modeled as an ordinal variable (0, 1-10, 11-100, 101-400, >400) the c-statistic for the CAC model was 0.87 (p=0.03 vs FRS model) and NRI was 13.9% (p=0.011). Prior studies in older individuals (mean ages: 59 to 70) have reported changes in c-statistics from 0.04 to 0.11 and NRIs from 14%% to 35% (Table).
Conclusion: In a relatively young cohort, CAC significantly improved CHD risk classification. These findings suggest that CAC screening may be valuable in younger individuals.
- © 2013 by American Heart Association, Inc.