Introduction: High total cholesterol (TC) is a risk factor for the development of coronary artery calcium (CAC); however, long-term trajectories of change in TC and their associations with CAC are unknown. We aimed to identify TC trajectories of change throughout early adulthood and to determine their associations with presence of CAC during middle age.
Methods: We used data from the CARDIA study, a prospective cohort study of African Americans and whites aged 18-30 at baseline in 1985-1986. Cholesterol was measured 7 times: at baseline and years 2, 5, 7, 10, 15, and 20. CAC was measured at year 25. CARDIA participants on TC-lowering medications were excluded. Group-based modeling (PROC TRAJ) was used to identify trajectories in TC change over time. The optimal number of trajectories was determined comparing Bayesian information criterion. Logistic regression was used to examine the association between TC change trajectories and CAC> 0 at year 25 adjusted for age, sex, race, blood pressure, smoking, glucose, BMI, and baseline TC.
Results: Among 4,212 individuals we identified 4 distinct trajectories of change in TC: decrease (7.2% of the sample), stable (43.5%), moderate increase (42.2%) and major increase (7.1%). Individuals in the decreasing group had the highest baseline TC. Participants in the major increase group had the lowest baseline TC and were more likely to be male and white. After adjusting for baseline TC, when compared to the stable trajectory group, the major increase group was significantly associated with CAC (OR = 1.94 95% CI: 1.3, 2.9), the decreasing and stable increasing trajectories were not significantly associated with CAC.
Conclusion: These findings suggest that an increasing TC trajectory, despite lower baseline TC levels, is associated with increased risks for subclinical atherosclerosis. Understanding long-term trajectories in TC may assist in the identification of individuals with CAC in middle age.