Abstract: We screened 17,055 records identified through searches of databases. We obtained 746 full-text articles and assessed them for relevance. We scrutinised 49 studies to establish their eligibility for inclusion in the review and excluded 48, primarily because participants were not patients presenting solely with exertional leg pain, investigators used no reference standard or investigators used neither angiography nor duplex ultrasonography as the reference standard. We excluded most studies for more than one reason. Only one study met the eligibility criteria and provided limb-level accuracy data from just 85 participants (158 legs). This prospective study compared the manual doppler method of obtaining an ABI (performed by untrained personnel) with the automated oscillometric method. Limb-level data, as reported by the study, indicated that the accuracy of the ABI in detecting significant arterial disease on angiography is superior when stenosis is present in the femoropopliteal vessels, with sensitivity of 97% (95% confidence interval (CI) 93% to 99%) and specificity of 89% (95% CI 67% to 95%) for oscillometric ABI, and sensitivity of 95% (95% CI 89% to 97%) and specificity of 56% (95% CI 33% to 70%) for doppler ABI. The ABI threshold was not reported. Investigators attributed the lower specificity for doppler to the fact that a tibial or dorsalis pedis pulse could not be detected by doppler in 12 of 27 legs with normal vessels or non-significant lesions. The superiority of the oscillometric (automated) method for obtaining an ABI reading over the manual method with a doppler probe used by inexperienced operators may be a clinically important finding. Evidence about the accuracy of the ankle brachial index for the diagnosis of PAD in people with leg pain on exercise that is alleviated by rest is sparse. The single study included in our review provided only limb-level data from a few participants. Well-designed cross-sectional studies are required to evaluate the accuracy of ABI in patients presenting with early symptoms of peripheral arterial disease in all healthcare settings. Another systematic review of existing studies assessing the use of ABI in alternative patient groups, including asymptomatic, high-risk patients, is required.

Plain-language summary: The ABI test is non-invasive and inexpensive and is widely used clinically; therefore, we have reviewed all available reports obtained from a wide search of databases of medical literature to estimate its accuracy in identifying PAD in people who experience pain on walking that goes away after rest. Two review authors independently assessed studies that met inclusion criteria of the review, including use of a cross-sectional study design; enrolment of participants with pain on walking that got better with rest; and use of duplex ultrasonography or angiography to check that results of the ABI test were accurate. One study met our criteria and provided data from 85 participants (158 limbs). Investigators compared the manual doppler method of measuring ABI with the automated method. Researchers provided only data for legs as opposed to data for patients; we were therefore unable to recalculate the analysis at the whole-participant level. In conclusion, we found little evidence about the accuracy of the ankle brachial index for diagnosing PAD in people presenting with exertional leg pain. The study included in our review had some flaws, and well-designed cross-sectional studies are needed to measure the accuracy of the ABI for diagnosing PAD in patients with early symptoms.