Validation of a new method of detecting peripheral artery disease by determination of ankle-brachial index using an automatic blood pressure device.

Abstract

Peripheral artery disease (PAD) is a predictor of total and cardiovascular mortality; its most valuable simple index is the ankle-brachial index (ABI). The present study was designed to assess whether a commercially available automatic device could be used to determine ABI in comparison with the classical Doppler method. The ABI was defined as the ratio of systolic blood pressure at each ankle to the maximal brachial systolic pressure, a pathological index being defined for a ratio <0.90. The ABI were calculated in 219 consecutive patients (aged 55 +/-19 years) with systolic blood pressure measured either by using a mercury sphygmo-manometer and a continuous-wave Doppler probe or an automatic manometer Omron M4. This device has been validated for measurements in upper limbs, and so the authors undertook validation in the lower limbs versus intraarterial measurements. There was an excellent correlation between intraarterial measurements and automatic readings in the range of 70-220 mm Hg, r=0.99, p<0.001. The systolic pressures measured in upper limbs correlated well in the right (r=0.87, p<0.001) and the left (r=0.89, p<0.001) upper limbs; and in the left (r=0.72, p<0.001) and the right (r=0.68, p<0.001) lower limbs. Correlations between ABI in both methods were good in the left (r=0.66, p<0.001) and the right (r=0.61, p<0.001) lower limbs. The sensitivity (76%), specificity (95%), positive predictive value (86%), negative predictive value (90%), and global accuracy (89%) of a pathological automatic index to predict an abnormal Doppler index were good. The use of a simple, automatic blood pressure device to determine ABI appears feasible, easy, and precise. It would provide a practical tool for physicians not trained in Doppler to detect PAD.