Reclassification of coronary heart disease risk in a primary prevention setting: traditional risk factor assessment vs. coronary artery calcium scoring

Background: In a primary prevention screening program of asymptomatic middle-aged subjects, we sought to assess the degree of risk-reclassification provided by traditional risk assessment vs. coronary artery calcification scoring (CACS). Methods: A total of 1,806 consecutive asymptomatic subjects (age 55 years, 76% men), who underwent comprehensive screening in a primary prevention clinic between 3/2016 and 9/2017 were included. Standard risk factors, C-reactive protein (CRP) and CAC scoring were performed. % 10-year coronary heart disease (CHD) risk was calculated using Reynolds Risk Score (RRS), atherosclerotic cardiovascular disease (ASCVD) score and multiethnic study on subclinical atherosclerosis (MESA) CACS were calculated. % 10-year CHD risk for all scores was categorized as follows: <1%, 1-5%, 6-10% and >10%. Results: Mean CRP, RRS, ASCVD and MESA-CACS were 2.1 +/- 4.2, 3.7 +/- 4, 4.9 +/- 6, 4.9 +/- 5; 54% had CAC of 0, while 21% had CAC >75th percentile. There was a significant, but modest correlation between MESA-CAC score and (I) RRS (r=0.62) and (II) ASCVD scores (r=0.65, both P<0.001). Compared to MESA-CAC, for RRS, (I) 188 (10%) patients had a downgrade in risk and (II) 538 (30%) patients had an upgrade in risk (40% reclassification of risk). Similarly, compared to MESA-CAC, for ASCVD score, (I) 412 (23%) patients had a downgrade in risk and (II) 329 (18%) patients had a downgrade in risk (41% reclassification of risk). Conclusions: In a primary prevention screening program of asymptomatic middle-aged patients, RRS overestimates and ASCVHD underestimates 10-year CHI) risk vs. MESA-CACS. Addition of CACS results in significant risk reclassification.