Atherosclerosis Risk in Communities Study (ARIC)

Background/Questions

ARIC, a multicenter prospective cohort study begun in 1986, has two main goals: 1. to explore ‘new’ CVD risk factors and intermediate CVD events based on newer knowledge and technology, and 2. to monitor trends in CVD rates in different U.S. populations (Forsyth County, North Carolina; Jackson, Mississippi; Suburbs of Minneapolis, Minnesota; and Washington County, Maryland). It is intended to provide a model for systematic regional trend modeling and to continue the prospective approach to CVD risk with novel risk factors and diverse populations.

Method/Design

At the baseline examination, information was obtained in 15,792 men and women, aged 45-64 years, about medical history, physical activity, anthropometry, medication use and dietary intake. Measures were made of serum lipids and lipoproteins, hemostatic factors, and pulmonary function, and a brief physical examination and ECG were performed. Examinations for the detection of subclinical atherosclerosis included noninvasive scanning of the carotid and popliteal arteries by B-mode ultrasonography.

Participants were re-examined in 1990-1992 and 1993-1995, with good to excellent clinic follow-up rates. Annual telephone calls were made to assess subsequent hospitalizations and mortality between clinic visits. Surveys of discharge lists from local hospitals, death certificates from vital statistics offices, and review of ECGs every 3 years at clinic visits were used to ascertain the occurrence of study endpoints.

Results

The risk of developing diabetes was approximately 2.4-fold greater in African American women than white women and about 1.5-fold greater in African American men than in white men. After controlling for potential confounding factors, racial differences in potentially modifiable risk factors, particularly adiposity, accounted for almost half of the excess risk of diabetes in African American women.
Both mean total cholesterol levels and the prevalence of hypercholesterolemia consistently declined over the 3 years covered by the baseline visit for all age-gender-race groups. The plasma concentrations of fibrinogen were significantly associated with carotid atherosclerosis after taking other atherosclerosis risk factors into consideration.

The multivariable-adjusted relative risks of CHD increased similarly in men and women and whites and African Americans across quartiles of increasing body mass index and waist/hip ratio.
Exposure to cigarette smoke was associated with progression of atherosclerosis and was greater for subjects with diabetes and hypertension.

High insulin levels were associated with the development of one or more metabolic syndrome components, as was a BMI >30, and a high waist-to-hip ratio.

A variety of possible risk and protective factors were examined in relation to subclinical atherosclerosis. Dietary intake of several antioxidants were inversely associated with wall thickness of the carotid artery.

Measures of thrombosis and fibrinolysis were associated with early indicators of atherosclerosis as were a number of conventional CHD risk factors. Little support was provided for the hypothesis that chlamydia pneumoniae infection is a risk factor for clinical CHD. Dietary intake of several antioxidants was inversely associated with intima-media wall thickness of the carotid artery. Measures of thrombosis and fibrinolysis were also associated with early indicators of atherosclerosis as were a number of conventional CHD risk factors. Strong associations between LDC-C, HDL-C, triglycerides and lipoprotein(a) and risk of CHD were observed in men and in women, and no threshold levels were found. The rate of stroke was excessive among those with white matter lesions of the brain.

In the surveillance component of ARIC, decreases in mortality rates due to CHD occurred among all race/sex groups with the grea