Can we measure the ankle-brachial index using only a stethoscope? A pilot study

Background. Ankle-brachial index (ABI) is an excellent method for the diagnosis of peripheral arterial disease (PAD) when it is performed with Doppler. However, this device is not always available for primary care physicians. The ABI measured with stethoscope is an easy alternative approach, but have not been proved to be useful. Objective. To assess the accuracy of the ABI measured using a stethoscope comparatively to that of the current eligible method for the diagnosis of PAD, the Doppler ABI, and describe the characteristics of this new approach. Methods. We conducted a diagnostic study of ABI measured with a stethoscope and a Doppler probe and compared the results. Eighty-eight patients were accessed by both methods. Results. Mean stethoscope ABI, 1.01 +/- 0.15, and mean Doppler ABI, 1.03 +/- 0.20, (P = 0.047) displayed a good correlation. Measurements of stethoscope ABI diagnostic accuracy in recognizing a Doppler ABI are described. The comparison of this data with the current gold standard method results gave a sensitivity of 71.4% [95% confidence interval (CI), 41.9-91.6] and specificity of 91.0% (95% CI, 81.5-96.6), with predictive positive value of 62.5% (95% CI, 38.6-81.5) and negative predictive value of 93.8% (95% CI, 85.2-97.6). The study accuracy was 87.7%. The area under the ROC curve was 0.895 (95% CI, 0.804-0.986, P < 0.0001). Conclusions. According to our study, the stethoscope ABI is a useful method to detect PAD and it may be suitable for its screening in the primary care setting.