T he ankle-brachial index (ABI) is the ratio of the systolic blood pressure (SBP) measured at the ankle to that measured at the brachial artery. Originally described by Winsor 1 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 atherosclerosis 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 ABIThe 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][8][9] In a review of 100 randomly selected reports using the ABI, multiple variations in technique were identified, including the position of the patient during measurement, the sizes of the arm and leg cuffs, the location of the cuff on the extremity, the method of pulse detection over the brachial artery and at the ankles, whether the arm and ankle pressures were measured bilaterally, which ankle pulses were used, and whether a single or replicate measures were obtained. 10 There is controversy about what ABI threshold should be used to diagnose PAD. The ABI threshold most commonly used is Յ0.90 based on studies reporting Ͼ90% sensitivity and specificity to detect PAD compared with angiography. 2,3 These studies were limited in that they included mostly older white men with PAD or who were at high risk for PAD and compared them with a younger healthy group. A recent metaanalysis of 8 studies of diverse populations, including diabetic patients, confirmed a high specificity but lower sensitivity (at best Ͻ80%) than that reported in earlier studies. 11 Similar to other vascular markers such as carotid intimamedia thickness 12 or coronary artery calcium score, 13 standardization of the techniques used to measure the ABI and the calculation and interpretation of its values is necessary.
Aims and ScopeThe goals for this document are to provide a comprehensive review of the relevant literature on the measurement of the The American Heart Association makes every effort to avoid any actual or potential conflicts of interest that may arise as a result of an outside relationship or a personal, professional, or business interest of a member of the writing panel. Specifically, all members of the writing group are required to complete and submit a Disclosure Questionnaire showing all such relationships that might be perceived as real or potential conflicts of interest.This statement was approved by the American Heart Association Science Advisory and Coordinating Committee on September 10, 2012. A copy of the document is available at http://my.americanheart.org/statements by selecting either the "By Topic" link or the "By Publication Date" link. To purchase additional repri...