Recommendations for Resting ABI for Diagnosing PAD
COR	LOE	Recommendations
I	B-NR	In patients with history or physical examination findings suggestive of PAD (Table 5), the resting ABI, with or without segmental pressures and waveforms, is recommended to establish the diagnosis.64–69
See Online Data Supplement 4.		The resting ABI is obtained by measuring systolic blood pressures at the arms (brachial arteries) and ankles (dorsalis pedis and posterior tibial arteries) in the supine position by using a Doppler device. The ABI of each leg is calculated by dividing the higher of the dorsalis pedis or posterior tibial pressure by the higher of the right or left arm blood pressure.27 In patients with a history or physical examination suggestive of PAD, the ABI has good validity as a first-line test in the diagnosis of PAD, as shown by vascular imaging, with sensitivities ranging from 68% to 84% and specificities from 84% to 99%.64–69 Segmental lower extremity blood pressures and Doppler or plethysmographic waveforms (pulse volume recordings) can be used to localize anatomic segments of disease (eg, aortoiliac, femoropopliteal, infrapopliteal).34,70,71
I	C-LD	Resting ABI results should be reported as abnormal (ABI ≤0.90), borderline (ABI 0.91–0.99), normal (1.00–1.40), or noncompressible (ABI >1.40).27,67–69,72
See Online Data Supplement 4.		Standardized reporting improves communication among healthcare providers. Calculated ABI values should be recorded to 2 decimal places. Patients with ABI ≤0.90 are diagnosed with PAD.67–69 Those with ABI 0.91 to 0.99 may possibly have PAD and should undergo exercise ABI, if the clinical suspicion of PAD is significant (Tables 4 and 5).73,74 Values >1.40 indicate that the arteries were not able to be compressed, which is more common among individuals with diabetes mellitus and/or advanced chronic kidney disease. In the setting of noncompressible ABI values, additional imaging can be used to diagnose PAD if the clinical suspicion is significant (Figures 1 and 2).72 These cutpoints for ABI interpretation have been previously proposed and represent a reasonable standardized categorization.27
IIa	B-NR	In patients at increased risk of PAD (Table 4) but without history or physical examination findings suggestive of PAD (Table 5), measurement of the resting ABI is reasonable.54,55,75–97
See Online Data Supplements 3 and 4.		The ABI test is noninvasive, is simple to perform, and has minimal risks, making it suitable for use in asymptomatic individuals. Previous studies have demonstrated a significant prevalence of abnormal resting ABI among asymptomatic patients with risk factors for PAD.55,79,95 A significant body of evidence demonstrates that patients with an abnormal ABI who are asymptomatic have poorer cardiovascular morbidity and mortality outcomes than do patients with normal ABI.79–87 While there is no conclusive evidence that aspirin treatment changes cardiovascular or limb outcomes in this population, in 1 cohort study of 5480 patients with asymptomatic PAD, statin treatment improved cardiovascular outcomes.75–78,96
		There is also evidence that asymptomatic patients with a low resting ABI have a poorer functional status and a more rapid rate of functional decline than do patients with a normal ABI.54,88–92 Although physical activity has been shown to be associated with improvement in functional status in patients with asymptomatic PAD,93,94 the benefit of resting ABI testing to identify asymptomatic patients who are at increased risk of functional decline and may benefit from structured exercise programs remains to be determined.
III: No Benefit	B-NR	In patients not at increased risk of PAD (Table 4) and without history or physical examination findings suggestive of PAD (Table 5), the ABI is not recommended.95,98
See Online Data Supplement 4.		The prevalence of PAD among individuals without risk factors for atherosclerosis and who are <50 years of age is low. Data from population-based cohort studies have demonstrated a low prevalence (approximately 1%) of abnormal resting ABI among individuals <50 years of age.95,98 In the NHANES (National Health and Nutrition Study), approximately 95% of participants with an abnormal resting ABI had at least 1 risk factor for atherosclerosis.95 The yield of ABI testing among younger, asymptomatic individuals without risk factors for atherosclerosis is low, and these patients should not be routinely tested for PAD.95,98