Abstract 3575: Carotid Intima-media Thickness Improves Coronary Heart Disease Risk Prediction In The Atherosclerosis Risk In Communities (ARIC) Study
Background: Carotid intima-media thickness (CIMT) is an independent predictor of cardiovascular disease. It has been suggested by some that CIMT be used as a screening tool in the general population. We investigated if CIMT improves coronary heart disease (CHD) risk stratification when added to traditional risk factors (TRF) (age, gender, HDL cholesterol, total cholesterol, diabetes, hypertension and cigarette smoking) in a healthy middle aged population in the ARIC study.
Methods: Participants in the ARIC study (n=13145) without baseline CHD or stroke and with CIMT measurements available were included for this analysis. Using Cox proportional hazards models, models were fitted using TRF alone and in addition to CIMT and the number of patients reclassified by adding CIMT was evaluated. The expected and observed incident CHD events using TRF alone and adding CIMT were compared using the Hosmer-Lemeshow statistic.
Results: Using TRF, 53.2%, 22.5%, 19% and 5.2% of the study population were classified as having <6%, 6 –10%, 10 –20% and >20% 10 year risk for CHD respectively. The addition of CIMT (quartile 4 versus quartile 1) to TRF in the entire study population (n=13145), females (n=7463) and males (n=5682) was associated with respective hazard ratios of 1.92 (p<0.0001), 1.72 (p=0.0002), 2.22 (P<0.0001) and improved the area under the ROC curve from 0.747 to 0.757, 0.802 to 0.808 and 0.683 to 0.702 respectively. The addition of CIMT to TRF reclassified 5.55%, 33.81%, 26.64% and 20.49% patients in the <6%, 6 –10%, 10 –20% and >20% risk respectively (table⇓). The model using CIMT + TRF had a better fit when observed and expected events were compared (Hosmer-Lemeshow test chi-square 34.88 (TRF alone), 23.76 (TRF + CIMT)).
Conclusion: The addition of CIMT to TRF modestly improved CHD risk prediction in middle aged asymptomatic adults in the ARIC study and reclassified individuals primarily in the intermediate and high risk groups. The addition of CIMT was more beneficial in males.