Which and how many screening tests for an accurate diagnosis of peripheral artery disease in patients with diabetic foot ulcers? A retrospective study

Background and aim: To retrospectively evaluate accuracy of screening tests for peripheral artery disease (PAD) in patients with diabetic foot ulcers (DFUs) and analyze the variation of these parameters when combining more tests together. Methods and results: PAD was diagnosed using Duplex-Ultrasound Scan (DUS). The following screening tests were evaluated: ankle systolic pressure, ABI (Ankle-Brachial Index), TP (Toe Pressure), TBI (Toe-Brachial Index), and wave-form analysis (WFA). Sensitivity, specificity, PLR, NLR (Positive and Negative Likelihood Ratio), and accuracy were calculated for each test and for multiple combinations (considering positive those cases in which at least one test was positive). Out of 97patients, 64 had PAD. TBI, TP, and WFA sensitivity (1.0, 1.0, and 0.83, respectively) and specificity (0.57, 0.43, and 1.0, respectively) were superior to those obtained with ABI (0.82 and 0.64). Among combination of two tests, those of pedal pulses with either TBI or WFA had a better performance than that with ABI. The combination of three tests further increased sensitivity, without reducing specificity. Conclusions: DUS is the golden standard for diagnosing PAD in patients with DFU. The use of combinations of tests (in particular, WFA + ABI or WFA + TBI) as a first-step can be a valid alternative in case of limited resources.