Abstract 4985: Are All Patients Considered “Low Risk” for Coronary Heart Disease Really Low Risk? An Analysis from the Atherosclerosis Risk in Communities (ARIC) Study

Low risk for coronary heart disease (CHD) is defined by ATP III as a 10 year risk of <10%. There have been suggestions, however, that a 10 year CHD risk of 5–10% be considered as intermediate risk. The addition of carotid intima media thickness (CIMT) has been shown to improve CHD risk prediction when added to traditional risk factors (TRF) (age, gender, high density lipoprotein cholesterol, total cholesterol, diabetes, hypertension and cigarette smoking) in the ARIC study. We investigated the absolute event rates with and without the addition of CIMT to TRF in the ARIC study and determined the impact in the 0–10% risk group. 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 the participants were classified into various risk categories using TRF and further classified by sex specific CIMT (categorized as <25 th , 25 th to 75 th and >75 th percentile). The absolute event rates were then described in each group (table ). Over a mean follow up of 13.8 years, 1601 (12.2%) individuals had incident CHD events. Approximately 31% of these incident CHD events were in the 5–10% risk group which made up 28% of the study while only 16% of the incident CHD events occurred in the 0–5% risk group which made up 47% of the study population. The 5–10% group had event rates (13.7%) greater than the study average (12.2%), especially in those with thicker CIMT (>75 th percentile, event rate 17%), and greater event rates than those in the 0–5% risk group (4.1%) (table ). Given the notably higher observed CHD risk in the 5–10% group (especially in those with thicker CIMT) relative to the 0–5% group, the availability of safe, low cost lipid lowering medications and low risk tests such as ultrasound that may improve risk stratification, it may be time to evaluate the low risk group more carefully for cardiovascular preventive therapies. Table. Incident CHD in the various risk groups over a mean follow up of 13.8 years in the ARIC study