Improving the clinical examination for a low ankle-brachial index

Abstract

We sought to determine clinical examination features that predict an abnormal ankle-brachial index (ABI). Eleven United States and Canadian university-affiliated practices participated. Patients over age 55 (n = 218) presenting for an outpatient appointment in a general medical clinic. We excluded patients with amputations or acute leg pain. A standard clinical examination was performed consisting of historical features and physical examination findings with Doppler ausculation. The most efficient findings were a. presence of only one Doppler-auscultated posterior tibial artery component [LR = 7.0; (95% CI 4.4, 11.6)], and b. absence of a palpable pulse [LR = 4.6; (95% CI 3.2, 6.6)]. We derived a score based on the number of auscultated components, grade of palpated pulse, and history of myocardial infarction (LR_{score < 6} = 7.8; LR_{score ≥ 6} = 0.2; c index = 0.93). Clinicians required a median 2.5 min to collect the clinical information and derive the score (interquartile range 1.8 to 3.6 min), versus 8.5 min for the ABI (interquartile range 7.4 to 9.4 min). Palpation and Doppler auscultation of the posterior tibial artery, combined with knowledge of prior myocardial infarctions, were the most effective and efficient findings for patients in general medical clinics. A score based on these findings appears promising as a screening tool for a low ABI.