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The resting ankle-brachial index (ABI) is a non-invasive method to assess the patency of the lower extremity arterial system and to screen for the presence of peripheral occlusive arterial disease. To determine how the ABI is associated with clinical coronary heart disease (CHD), stroke, preclinical carotid plaque and far wall intimal-medial thickness (IMT) of the carotid and popliteal arteries, we conducted analyses in 15 106 middle-aged adults from the baseline examination (1987-1989) of the Atherosclerosis Risk in Communities (ARIC) Study. The prevalence of clinical CHD, stroke/transient ischemic attack (TIA) and preclinical carotid plaque increased with decreasing ABI levels, particularly at those of 0.90 (age-adjusted odds ratio (OR) ranging from 2.2 (95% CI: 1.0-5.1) in African-American men to 3.3 (95% CI: 2.1-5.0) in white men). Men with ABI 0.90 (age-adjusted OR: 4.2 (95% CI: 1.8-9.5) in African-American men and 4.9 (95% CI: 2.6-9.0) in white men). In women the association was weaker and not statistically significant. Among those free of clinical cardiovascular disease, individuals with ABI 0.90 (age-adjusted ORs ranging from 1.5 (95% CI: 1.0-1.9) in white women to 2.6 (95% CI: 1.0-6.6) in african-american men). The ABI was also inversely associated with far wall IMT of the carotid arteries (in both men and women) and the popliteal arteries (in men only). The associations of ABI with clinical CHD, stroke, preclinical carotid plaque and IMT of the carotid and popliteal arteries were attenuated and often not statistically significant after further adjustment for LDL cholesterol, cigarette smoking, hypertension and diabetes. These data demonstrate that low ABI levels, particularly those of < 0.90, are indicative of generalized atherosclerosis.

An association between reduced pulmonary function and increased risk of atherosclerotic vascular events has been reported. The mechanisms underlying this association are unknown, but are unlikely to be entirely due to smoking given the presence of the association among non-smokers. Few studies have examined the cross-sectional association between subclinical atherosclerosis and pulmonary function. In 14,000 adults in the ARIC Study, we examined the cross-sectional relationship between lung function, measured by the forced expiratory volume at 1s (FEV(1)), and three markers of subclinical atherosclerosis: ankle-brachial index (ABI), carotid intimal-medial thickness (IMT), and presence of carotid plaques. Mean FEV(1) was computed by ABI category, IMT category, or plaque status, in the full cohort and after stratification by smoking status, adjusted for age, gender, race, study center, height, height-squared, smoking, and pack years. Decreased FEV(1) was associated with decreased ABI and increased IMT in the full cohort and in each smoking group. Further adjustment for CVD risk factors did not alter the ABI association, but attenuated the IMT association, eliminating it in never smokers. Plaque was not associated with FEV(1). These findings suggest a complex relationship between FEV(1) and atherosclerotic vascular disease that invites further study.