What Is the Clinical Utility of the Ankle-Brachial Index in Patients With Diabetic Foot Ulcers and Radiographic Arterial Calcification?

The purpose of this study was to analyze the influence of radiographic arterial calcification (RAC) on the clinical interpretation of ankle-brachial index (ABI) values in patients with diabetic foot ulcers. We analyzed a retrospective clinical database of 60 patients with diabetic foot ulcers from the Diabetic Foot Unit (Complutense University, Madrid, Spain) between January 2012 and March 2014. For each patient, anteroposterior XR-plains were evaluated, and the ABI and toe-brachial index (TBI) were assessed by an experienced clinician. To analyze the correlation among quantitative variables, we applied the Pearson correlation coefficient. Fifty percent (n = 9/18) of our patients with a normal ABI and RAC had a TBI < 0.7 associated with peripheral arterial disease (PAD). In patients with RAC, the prevalence of a normal ABI (72%, 18/25) was higher than in patients without RAC (52%, 11/21). The Pearson correlation coefficient among the ABI and TBI in patients with an ABI < 1.4 (n = 46) was lesser (r = .484, P = .001) than in patients with an ABI < 1.4 but without RAC (n = 21; r = .686, P = .001). ABI values between 0.9 and 1.4 would be falsely considered as normal and could underestimate the prevalence of PAD, especially in patients with neuropathy, diabetic foot ulcers, or RAC.