Peripheral Vascular Disease, Council on Epidemiology and Prevention, Council on Clinical Cardiology, Council on Cardiovascular Nursing, Council on Cardiovascular Radiology and Intervention, and Council on Cardiovascular Surgery and Anesthesia

The ankle-brachial index (ABI) is the ratio of the systolicblood pressure (SBP) measured at the ankle to that mea-sured at the brachial artery. Originally described by Winsor1 in 1950, this index was initially proposed for the noninvasive diagnosis of lower-extremity peripheral artery disease (PAD).2,3 Later, it was shown that the ABI is an indicator of atheroscle-rosis at other vascular sites and can serve as a prognostic marker for cardiovascular events and functional impairment, even in the absence of symptoms of PAD.4–6 Rationale for Standardization of the ABI The current lack of standards for measurement and calculation of the ABI leads to discrepant results with significant impact from clinical, public health, and economic standpoints. Indeed, the estimated prevalence of PAD may vary substantially according to the mode of ABI calculation.7–9 In a review of 100 randomly selected reports using the ABI, multiple variations in techniqu