Race- and Sex-Specific Age at Which Coronary Artery Calcium Becomes Detectable Among Young Adults

BACKGROUND: Coronary artery calcium (CAC) is an excellent predictor of atherosclerotic cardiovascular disease (ASCVD) risk. Limited data exist on the age at which CAC transitions to nonzero among young adults. We aimed to assess the prevalence of CAC by the number of ASCVD risk factors and use this data to model the race- and sex-specific ages at which young adults transition to a CAC >0. METHODS: We included 17 285 participants aged 30 to 50 years from the CAC Consortium and the CARDIA (Coronary Artery Risk Development in Young Adults) study in this cross-sectional study. We estimated the burden of CAC by the number of ASCVD risk factors and used sex- and race-specific multivariable logistic regression models to predict the probability of CAC >0. From these, we estimated the age at CAC conversion from zero, using a minimum testing yield of 25%. RESULTS: Of the 17 285 participants included in this study (mean age, 43.3±4.7years, 66.9% men, and 87.5% White), 30.1% had CAC >0. The probability of CAC >0 at each specified age and risk factor profile was higher among men than women and White compared with Black individuals. With 2 ASCVD risk factors, the estimated age at which CAC became detectable was 36.1 (35.1–36.9) years for White men, 41.9 (40.6–43.2) years for Black men, 47.6 (46.3–48.9) years for White women, and 51.6 (48.2–54.5) years for Black women. CONCLUSIONS: The age at which CAC becomes detectable in young adults varies substantially by race, sex, and the number of ASCVD risk factors. Earlier initiation of CAC scans may be indicated in select subgroups at greater risk of premature atherosclerosis.