Validation study of automated oscillometric measurement of the ankle-brachial index for lower arterial occlusive disease by comparison with computed tomography angiography.

The ankle-brachial index (ABI) determined by the oscillometric method has been shown to reliably detect peripheral arterial disease (PAD), with highly correlations with the Doppler method. However, most of these studies were shown in cohorts with a small number of PAD patients, and no imaging studies have been performed. The purpose of this study is to evaluate the diagnostic accuracy and optimal threshold of oscillometric ABI for detecting PAD using computed tomography angiography (CTA) as a gold standard in a cohort that consists mostly of PAD patients. This retrospective study included 108 consecutive patients with 216 limbs. ABI measured by an oscillometric device was compared with CTA. The diagnostic accuracy of oscillometric ABI to detect ≥50% and ≥75% stenosis confirmed by CTA and the optimal ABI cutoff values were evaluated using receiver operating characteristic (ROC) curve analysis. The oscillometric ABI could not be measured in nine limbs. The mean ABI was 0.72±0.31. The areas under the ROC curves (AUCs) for detecting ≥50% and ≥75% stenosis with oscillometric ABI were 0.919 and 0.918, respectively. The optimal ABI cutoff values to detect these levels of stenosis were 0.99 (sensitivity, 90%: specificity, 85%) and 0.87 (sensitivity, 84%: specificity, 89%), respectively. If patients with diabetes mellitus (DM) were analyzed separately, the AUC for detecting ≥75% stenosis was 0.888. Oscillometric ABI had a high diagnostic accuracy to detect PAD using CTA as a gold standard. The diagnostic ability of ABI to detect PAD could be impaired by the presence of DM.