Race-ethnic differences in the extent, prevalence, and progression of coronary calcium.

OBJECTIVE: To compare across four race-ethnic groups the baseline prevalence and extent of coronary calcium and the 7-year rate of progression in the extent of coronary calcium.
DESIGN: The South Bay Heart Watch is a prospective cohort study designed to appraise the value of coronary calcium for predicting cardiovascular outcomes in asymptomatic adults with cardiac risk factors. Statistical analyses were conducted to evaluate ethnic differences in the prevalence, extent, and progression of coronary calcium among Caucasian, African-American, Hispanic, and Asian participants.
SETTING: Population-based study. PATIENTS OR PARTICIPANTS: Between December 1990 and December 1992, 1289 participants without coronary heart disease underwent baseline risk factor screening and computed tomography for coronary calcification (Cohort 1). Seven years later, 828 (64%) participants returned for follow-up evaluation and re-scanning (Cohort 2). MAIN OUTCOME MEASURES: Prevalence, extent, and progression of coronary artery calcium.
RESULTS: In Cohort 2, compared to Whites, African Americans had a lower prevalence of coronary calcium at baseline (P=.012) and follow-up (P=.005), smaller calcium scores at baseline (P=.005) and follow-up (P=.0004), and less progression (P=.001); Hispanics had a lower prevalence of coronary calcium at follow-up (P=.04) with smaller calcium scores (P=.011), and less progression (P=.009). In contrast, no differences were seen between Whites and Asian/Pacific Islanders. Race-ethnic differences in progression persisted after adjusting for risk factors and participation bias (P<.05).
CONCLUSIONS: The present results lend further credence to the notion that race-ethnic differences exist in the prevalence and rate of progression of coronary calcification. The relationship between calcification and the incidence of coronary heart disease in these race-ethnic groups needs further exploration.