A Simple Approach to the Identification of Guideline-Based Coronary Artery Calcium Score Percentiles (From the Multi-Ethnic Study of Atherosclerosis)

Absolute coronary artery calcium (CAC) scores and CAC percentiles can identify different patient groups, which could be confusing in clinical practice. We aimed to create a simple "rule of thumb" for identifying the American College of Cardiology/American Heart Association endorsed 75th CAC percentile based on age, gender, and the absolute CAC score. Using the Multi-Ethnic Study of Atherosclerosis, we calculated the age and gender-specific percent likelihood that a guideline-based absolute CAC score group (1 to 100, 100 to 300, >300) will place a patient above the 75th percentile. Also, we derived gender-specific age cutoffs by which 95% of participants with any (>0), moderate (≥100), or severe (≥300) CAC score would be over the 75th percentile. We repeated the analysis using the 90th percentile threshold and also conducted sensitivity analyses stratified by race. Any CAC >0 places 95% of women younger than 60 years and over 90% of men younger than 50 years over the 75th percentile. Moderate absolute CAC scores (>100) place nearly all men <60 years and all women <70 years over the 75th percentile. Confirmatory analysis for age cutoffs was consistent with primary analysis, with cutoffs of 48 years for men and 59 years for women indicating a 95% likelihood that any CAC would place patients over the 75th percentile. In conclusion, our study provides a simple rule of thumb (men <50 years and women <60 years with any CAC, men <60 years and women <70 years with CAC >100) for identifying CAC >75th percentile that might be readily adopted in clinical practice.