Abstract P154: Association of Coronary Calcium Score with Cardiovascular Risk Factors in African Americans: The Jackson Heart Study (JHS)

Background: It remains unclear if individuals with low Framingham risk score (FRS) could benefit from coronary artery calcium (CAC) screening for coronary heart disease (CHD) risk, especially in African Americans (AA) who have a lower prevalence of CAC and in whom the FRS is less robust. The CAC score has previously been shown to independently predict hard events in AA men and women. We assessed the association of CAC with cardiovascular risk factors and its distribution by the FRS categories in AA who were part of the Jackson Heart Study (JHS). Methods: CAC was measured with non-contrast cardiac CT in 2944 participants between April 2007 and February 2010 in the JHS, a NHLBI-funded cohort study of AA based in Jackson, MS. Participants were dichotomized based on the presence or absence of CAC. FRS was calculated based on 10 year risk for each participant and categorized as low (<10%), intermediate (10–20%) and high (>20%). Multi-variable linear and logistic regression analyses were used to estimate the associations of CAC with cardiovascular risk factors by FRS categories in AA. Results: The mean age of the cohort is 60 years, 65% were females, 26% had diabetes mellitus, 50% were obese (BMI≥30) and 30% were current or former smokers. Participants with CAC were significantly older (mean age 65 vs. 55 years, p<0.0001), had high mean SBP (131 vs.124mmHg, p<0.0001) and had lower HDL. Males were more likely to have CAC compared with females [odds ratio (95% CI): 1.50(1.29 – 1.75), p<0.0001], current and former smokers were also more like to have CAC compared with never smokers [OR (95%CI): 2.24(1.75 – 2.89), p<0.006 and 2.10(1.73 – 2.55), p<0.002 respectively]. Diabetics were more likely to have CAC compared with non diabetics [OR (95%CI): 3.27(2.70 – 3.96), p<0.0001]. Total cholesterol and BMI were not different among subjects with CAC or without CAC. The distribution of CAC stratified by FRS groups of low, intermediate and high 10 year risk of CHD results in mean [median, range] CAC scores of 132.3 [0, (0–3884)], 101.8 [0, (0–5498)] and 315.1 [33.8, (0–10801)] and CAC prevalence of 39.7%, 42.1%, and 65.8%, respectively. After adjusting for age, gender, smoking status, systolic blood pressure and diabetes status, subjects with high FRS were about 3 times as likely to have CAC compared with subjects in the intermediate or low risk category [OR(95%CI): 2.92(2.41 – 3.51), p<0.0001]. Individuals with intermediate FRS had similar rate of CAC compared with low FRS individuals. Conclusion: CAC in AA is strongly associated with traditional CV risk factors. Interestingly, AA with low and intermediate FRS have similar amounts and prevalence of CAC. This finding suggests that further refinement of traditional CHD risk models, such at FRS, may allow improved prediction of CHD and better targeting of prevention in the AA community.