Abstract P300: Major Risk Factors For Coronary And Aorto-iliac Calcium In Middle-aged Black And White Adults: Results From CARDIA

Abstract

Background: Abdominal aorto-iliac atherosclerosis occurs earlier in the course of disease than coronary artery atherosclerosis and is often present in persons free of coronary atherosclerosis. Accounting for this early stage of disease might improve the ability to evaluate risk factors for atherosclerosis. Objective: We examined the associations of major risk factors with the presence of coronary artery calcium (CAC) and abdominal aorto-iliac calcium (AoIC) in the absence of CAC in 1994 black and white men and women participating in the CARDIA study at the year 25 exam in 2010–11. Methods: Multinomial logistic regression was used to examine the associations of risk factors measured at year 15 with the presence of CAC and AoIC (Agatston scores ≥1) at year 25. Ordinary logistic regression was used to examine the associations of risk factors with presence of CAC (ignoring AoIC) at year 25. Results: 457 (22.9%) had both CAC and AoIC, 139 (7.0%) had CAC only, 632 (31.7%) had AoIC only, and 766 (38.4%) had neither. The 596 with CAC (+/−AoIC) were analyzed as one group vs. AoIC only, both in comparison with no calcification. Most risk factors had similar association with CAC (+/−AoIC) and AoIC only, including total and HDL cholesterol, triglycerides, systolic and diastolic blood pressure, smoking status, waist circumference and education. When comparing odds ratios (OR) for CAC (+/−AoIC) and AoIC only, both vs. no calcification, substantial differences were seen for comparisons of blacks vs whites (0.52 for CAC, p<0.0001 and 0.88 for AoIC, p=0.34), women vs men (0.34 for CAC, p<0.0001 and 0.96 for AoIC, p=0.77), and use vs. nonuse of drugs for blood pressure lowering (2.24, p=0.0023 and 1.27, p=0.36) and lipid lowering drugs (2.39, p=0.07 and 0.98, p=0.97). Accounting for the presence of AoIC without CAC resulted in uniform strengthening of the associations of risk factors with CAC. The most impressive change was for current smoking. The OR for CAC was 2.01 (95% CI: 1.53, 2.65) when ignoring AoIC and 4.47 (3.15, 6.32) when accounting for AoIC. AoIC alone was also strongly associated with smoking with an OR of 3.84 (2.80, 5.28). Conclusions: AoIC, an early manifestation of subclinical atherosclerosis, is associated with the major risk factors for CAC. The race and sex differences shown here, including little race or sex difference in AoIC only, are consistent with previous autopsy studies and deserve further etiologic research. Accounting for the presence of AoIC without CAC results in stronger estimates of risk factor associations with CAC. Studies that have not accounted for the presence of atherosclerosis in other vascular beds may have under-estimated the associations of established and novel risk factors with CAC.