Modeling the Recommended Age for Initiating Coronary Artery Calcium Testing Among At-Risk Young Adults

Background: There are currently no recommendations guiding when best to perform coronary artery calcium (CAC) scanning among young adults to identify those susceptible for developing premature atherosclerosis. Objectives: The purpose of this study was to determine the ideal age at which a first CAC scan has the highest utility according to atherosclerotic cardiovascular disease (ASCVD) risk factor profile. Methods: We included 22,346 CAC Consortium participants aged 30-50 years who underwent noncontrast computed tomography. Sex-specific equations were derived from multivariable logistic modeling to estimate the expected probability of CAC >0 according to age and the presence of ASCVD risk factors. Results: Participants were on average 43.5 years of age, 25% were women, and 34% had CAC >0, in whom the median CAC score was 20. Compared with individuals without risk factors, those with diabetes developed CAC 6.4 years earlier on average, whereas smoking, hypertension, dyslipidemia, and a family history of coronary heart disease were individually associated with developing CAC 3.3-4.3 years earlier. Using a testing yield of 25% for detecting CAC >0, the optimal age for a potential first scan would be at 36.8 years (95% CI: 35.5-38.4 years) in men and 50.3 years (95% CI: 48.7-52.1 years) in women with diabetes, and 42.3 years (95% CI: 41.0-43.9 years) in men and 57.6 years (95% CI: 56.0-59.5 years) in women without risk factors. Conclusions: Our derived risk equations among health-seeking young adults enriched in ASCVD risk factors inform the expected prevalence of CAC >0 and can be used to determine an appropriate age to initiate clinical CAC testing to identify individuals most susceptible for early/premature atherosclerosis.