Ankle brachial index useful in CVD risk assessment
When used in conjunction with the Framingham risk score, ankle brachial index (ABI) could improve the accuracy of CVD risk assessment.
ABI is the ratio of systolic pressure at the ankle to that in the arm.
This meta-analysis assessed the association between ABI and cardiovascular mortality and the incremental benefit gained over using the Framingham risk score alone.
It used data from 16 population cohort studies that included patients derived from a general population, with ABI measured at baseline, and followed up to detect total and cardiovascular mortality.
A total of 24,955 men and 23,339 women without a history of CHD were included in the studies, there were more than 480,000 person-years of follow-up and 9,924 deaths occurred.
The 10-year cardiovascular mortality was 18.7% in men with a low ABI (? 0.9) and 4.4% in men with an ABI of 1.11 to 1.40 (HR 4.2, 95% CI 3.3-5.4), and 12.6% and 4.1% for women with a low ABI and normal ABI respectively (HR 3.5, 95% CI 2.4-5.1). This elevated risk remained after adjusting for the Framingham risk score, with adjusted hazard ratios of 2.9 (95% CI 2.3-3.7) for men and 3.0 (95% CI 2.0-4.4) for women.
There has been much discussion of late about the estimation of cardiovascular risk. Risk algorithms are useful as guides to which patients may require intervention and, as ABI is a marker for peripheral vascular disease, it would seem logical that a combination of the standard risk dataset and ABI could improve the overall risk assessment.
Compared with other assessments of asymptomatic atherosclerosis, such as coronary calcium scoring and carotid artery intima-media thickness, ABI is simple, quick and inexpensive. However, it is questionable whether its use in primary care will become routine considering the possible number of patients involved.
Ankle Brachial Index Collaboration. Ankle Brachial Index Combined With Framingham Risk Score to Predict Cardiovascular Events and Mortality. JAMA 2008;300:197-208Reviewer
Dr Peter Savill
GPwSI Cardiology, Southampton