Background: The ankle-brachial index (ABI), i.e. the ratio of the ankle to brachial systolic blood pressure, is the golden standard for the diagnosis of peripheral arterial disease (PAD) and is a highly specific method for the assessment of vascular risk in otherwise asymptomatic patients.
Objective: To assess the diagnostic accuracy of the ABI measured by palpation in patients at increased cardiovascular risk in a primary care setting.
Methods: Twenty-four GPs enrolled 10 consecutive patients each, at intermediate cardiovascular risk, based on age >55 and <65 years and one or two associated major cardiovascular risk factors or age >65 and <80 years without associated cardiovascular risk factor. Clinical data recording and measurements of the ABI were performed. The design of the study was a prospective, blind comparison between the ABI measured by palpation by the GP and simultaneously by Doppler ultrasound by an angiologist (reference test).
Results: Out of 240 enrolled patients, 205 completed the study (35 lost to follow-up); in 9, ABI by palpation was not measurable. Out of the remaining 196 assessable patients, 8 (4.08%) had PAD. Sensitivity of the palpation method was 88% (95% confidence intervals: 65-100), specificity 82% (77-88), positive predictive value 18% (6-29), negative predictive value 99% (98-100), positive likelihood ratio = 4.98 (3.32-7.48) and negative likelihood ratio = 0.15 (0.02-0.95).
Conclusions: The measurement of ABI by palpation in the setting of primary care, in patients at intermediate cardiovascular risk, is a sufficiently sensitive method to consider its use as a screening test for the exclusion of PAD.