Social disadvantage, coronary artery calcium, and their interplay in the prediction of atherosclerotic cardiovascular disease events

Background and aims: Social determinants of health (SDOH) are key for the identification of populations at increased risk of atherosclerotic cardiovascular disease (ASCVD). However, whether at the individual level SDOH improve current ASCVD risk prediction paradigms beyond traditional risk factors and the coronary artery calcium (CAC) score, is unknown. We evaluated the interplay between CAC and SDOH in ASCVD risk prediction. Methods: MESA is a prospective study of US adults free of clinical ASCVD at baseline. We used an SDOH index inclusive of 14 determinants from 5 domains. The index ranged 0-1 and was divided into quartiles, with higher ones representing worse SDOH. Cox regression was used to evaluate the adjusted associations between CAC, SDOH, their interplay, and ASCVD events. The C-statistic was computed to assess improvement in risk discrimination for prediction of ASCVD events. Results: We included 6479 MESA participants (50% with CAC = 0, 24% CAC>100). ASCVD incidence increased with increasing CAC scores across SDOH quartiles. The lowest incidence was noted in those with CAC = 0 and favourable SDOH (2/1000 person-years) and highest in those with CAC>100 and most unfavourable SDOH (20.6/1000 person-years). While CAC was strongly associated with ASCVD across SDOH quartiles, SDOH was weakly associated with ASCVD across CAC strata. CAC improved the discriminatory ability of all prediction models beyond traditional risk factors, the improvement in C-statistic ranging +0.02 - +0.05. Improvements with SDOH were smaller, and were none on top of CAC. Conclusions: CAC improves ASCVD risk stratification across the spectrum of social vulnerability, while SDOH fail to improve risk prediction beyond traditional RFs and CAC.