Abstract 1907: Age-Gender based Coronary Artery Calcium Percentile Scores: Which Cutoffs to Use?
Background: Individuals with a CAC in the top quartile for their age are at significantly increased risk for future CHD events. As a result, age-gender based CAC ≥75th percentile derived from various cohorts of subjects are sometimes used to identify individuals candidates for aggressive preventive strategies. However, it is not clear whether within the same population those CAC cutoffs will vary according to increasing number of risk factors (RF) present. In this study we aim to establish reference CAC scores according to baseline RF.
Methods: We studied 8,619 consecutive, physician-referred, asymptomatic adults, (55±8 yrs, 67% males) who underwent electron-beam tomography between 1999 and 2002. CAC was calculated by Agatston method. Risk factors taken into account were family history of CHD, cigarette smoking, diabetes mellitus, dyslipidemia, and hypertension.
Results: In our study CAC ranged from 0 to 7,108, with a median (inter-quartile range) of 4 (0 – 85). The prevalence of CAC was 55% and increased linearly according to the increasing number of risk factors; 0 RF (n=3,262, 45%), 1 RF (n=3,141, 54%), 2 RF (n=1,662, 67%) and 3 RF (n=554, 78%), respectively. In a similar fashion the prevalence of CAC was higher with increasing age; <45 years (n=1699, 27%), 45–54 years (n=3436, 51%), 55– 64 years (n=2327, 70%) and ≥65 years (n=1157, 78%). When stratified according to risk factors, the age and gender based cutoffs for CAC ≥75th percentiles were significantly greater among individuals with higher numbers of risk factors (p<0.0001 for trend).
Conclusion: The overall CAC percentile cutoffs differ according to the clustering of RF and will reflect the group more prevalent in the study group. Clearly those subjects with no traditional risk factors have much lower CAC scores. In determining one’s biologic age, it may be better to compare a subject’s CAC score with the 75th percentile for the same age-gender group with 0 risk factors.