Key result
Peripheral arterial disease, defined by an ankle-brachial index < 0.90, significantly increased the risk of incident coronary heart disease, with hazard ratios ranging from 2.05 to 4.86 across race and gender subgroups.
Why the study?
Does a low ankle-brachial index (ABI) predict incident coronary heart disease in white and African American adults?
Cohort (n=13,678)
Yes
Does a low ankle-brachial index (ABI) predict incident coronary heart disease in white and African American adults?
Effect estimate: HR 2.81 (95% CI 1.77-4.45)
Absolute Event Rate: 21.8% vs 8%
A low ankle-brachial index is strongly associated with an increased risk of incident coronary heart disease, particularly in African American men, while high ABI values (>1.3) do not appear to increase CHD risk in this population.
May refine CHD risk assessment across groups; challenges prior high-ABI associations but leaves open causal validation.
BACKGROUND: Peripheral arterial disease (PAD), defined by a low ankle-brachial index (ABI), is associated with an increased risk of cardiovascular events, but the risk of coronary heart disease (CHD) over the range of the ABI is not well characterized, nor described for African Americans. METHODS: The ABI was measured in 12186 white and African American men and women in the Atherosclerosis Risk in Communities Study in 1987-89. Fatal and non-fatal CHD events were ascertained through annual telephone contacts, surveys of hospital discharge lists and death certificate data, and clinical examinations, including electrocardiograms, every 3 years. Participants were followed for a median of 13.1 years. Age- and field-center-adjusted hazard ratios (HRs) were estimated using Cox regression models. RESULTS: Over a median 13.1 years follow-up, 964 fatal or non-fatal CHD events accrued. In whites, the age- and field-center-adjusted CHD hazard ratio (HR, 95% CI) for PAD (ABI<0.90) was 2.81 (1.77-4.45) for men and 2.05 (1.20-3.53) for women. In African Americans, the HR for men was 4.86 (2.76-8.47) and for women was 2.34 (1.26-4.35). The CHD risk increased exponentially with decreasing ABI as a continuous function, and continued to decline at ABI values > 1.0, in all race-gender subgroups. The association between the ABI and CHD relative risk was similar for men and women in both race groups. A 0.10 lower ABI increased the CHD hazard by 25% (95% CI 17-34%) in white men, by 20% (8-33%) in white women, by 34% (19-50%) in African American men, and by 32% (17-50%) in African American women. CONCLUSION: African American members of the ARIC cohort had higher prevalences of PAD and greater risk of CHD associated with ABI-defined PAD than did white participants. Unlike in other cohorts, in ARIC the CHD risk failed to increase at high (>1.3) ABI values. We conclude that at this time high ABI values should not be routinely considered a marker for increased CVD risk in the general population. Further research is needed on the value of the ABI at specific cutpoints for risk stratification in the context of traditional risk factors.
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Weatherley et al. (2007) conducted a cohort in Peripheral Arterial Disease (n=13,678). Peripheral arterial disease (ABI < 0.90) vs. Normal ABI (≥ 0.90) was evaluated on Incident fatal and non-fatal coronary heart disease (CHD) (HR 2.81, 95% CI 1.77-4.45). Peripheral arterial disease, defined by an ankle-brachial index < 0.90, significantly increased the risk of incident coronary heart disease, with hazard ratios ranging from 2.05 to 4.86 across race and gender subgroups.
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