Coronary artery calcium (CAC), a marker of subclinical atherosclerosis, predicts coronary artery disease (CAD) events, but the best use of CAC in risk prediction remains unclear. We examined whether group-based trajectory modeling of CAC in the Coronary Artery Calcification in Type 1 Diabetes (CACTI) study could independently predict CAD events. Four CAC trajectory groups (Figure 1a) were identified using longitudinal CAC in people free from CAD (Proc TRAJ in SAS Version 9.4), and these groups were used to predict a subsequent CAD event (myocardial infarction or coronary revascularization) using survival analysis. People with type 1 diabetes (T1D) were more likely to be in higher CAC trajectory groups than those without diabetes (non-DM, p<0.0001). Over 17,417 person-years of follow-up, 75 CAD events occurred (56 in T1D and 19 in non-DM individuals). Higher CAC trajectory group predicted CAD events in a dose-response manner (Figure 1b). In cox proportional hazards adjusted for age, sex, T1D, smoking, LDL, HDL, triglycerides and systolic blood pressure, being in a higher CAC group increased CAD risk, with a 33-fold increased risk in Group 4 (95% CI 12-91). A 3.3-fold excess risk (95% CI 1.7-6.4) for CAD remained for people with T1D. CAC trajectory group modeling can identify individuals at very high risk for a CAD event. However, T1D increases CAD risk independently of traditional risk factors and CAC trajectory.
J.K. Snell-Bergeon: Stock/Shareholder; Self; Abbott. Research Support; Self; Roche Diagnostics Corporation. A. Keshawarz: None. G.L. Kinney: None. I.E. Schauer: None. V.N. Shah: None. L. Pyle: None.