Abstract Body: Background
Coronary artery calcium (CAC) is a well-established marker of subclinical atherosclerosis and of cardiovascular risk. Identifying modifiable risk factors early in life such as body mass index (BMI) and waist-to-hip ratio (WHR) that predict development and progression of CAC in midlife can guide early intervention to decrease cardiovascular risk.

Hypothesis
We hypothesize that higher BMI and WHR in young adulthood is associated with both the presence and progression of CAC 10 years later.

Methods
We analyzed participants from the Coronary Artery Risk Development in Young Adults (CARDIA) Study with BMI and WHR measured at Y5 (Ages 23 to 35), and CAC measured between Y15-25 (ages 33 to 55). We used logistic regression models to assess the association between BMI/WHR and the presence of CAC (Agatston score >0) at Y15, and a repeated-measures GEE linear model to assess the association between BMI/WHR and progression of CAC (log Agatston score) from Y15 to Y25. We conducted nested models adjusting for demographic variables (age, sex, race) and cardiovascular risk factors (diabetes, hypertension, smoking status, total cholesterol, lipid-lowering pharmacotherapy use).

Results
A total of 2,838 participants had full data on obesity measures and CAC. Patients in higher quartiles of both BMI and WHR at Y5 had higher systolic blood pressures and total cholesterol. For each 5 kg/m² higher BMI at Y5, there was an associated increase in the prevalence of CAC>0 at Y15 (i.e., 10 years later) by 28% (OR: 1.28, 95% CI: 1.13 to 1.44, P= 0.001), adjusting for age, sex, and race; however, this association was attenuated after full adjustment (OR: 1.12, 95% CI: 0.98 to 1.29). For each 0.1 increase in WHR at Y5, there was an associated increase in the prevalence of CAC>0 at Y15 by 31% (after full adjustment (OR: 1.31, 95% Ci: 1.01, 1.69). There was an association of change in slope of yearly CAC progression between Y15-25 which increased by 18% for every 5 kg/m² higher BMI and by 58% for every 0.1 higher WHR assessed in young adulthood (Figure).

Conclusion
BMI and WHR measured in young adulthood are both associated with the presence and progression of CAC 10-20 years later; however, WHR may be a stronger predictor of CAC and progression of CAC than BMI.