Diagnostic Accuracy of Point-of-care Tests Used to Detect Arterial Disease in Diabetes: TEsting for Arterial Disease in Diabetes (TrEAD) Study

We compared the diagnostic performance of a novel point-of-care duplex ultrasound test (podiatry ankle duplex scan; PAD-scan) against commonly used bedside tests for the detection of peripheral arterial disease (PAD) in diabetes. PAD is a major risk factor for diabetic foot ulceration and amputation. Its diagnosis is fundamental though challenging. Although a variety of bedside tests are available, there is no agreement as to which is the most useful. PAD-scan may be advantageous over current tests as it allows for vessel visualisation and more accurate arterial waveform assessment. However, its accuracy has not been previously evaluated. From March to October 2019, we recruited 305 patients from two diabetic foot clinics. The diagnostic performance of ankle-brachial pressure index (ABPI), toe-brachial pressure index (TBPI), transcutaneous pressure of oxygen (TcPO2), pulse palpation and ankle waveform assessment using PAD-scan and Doppler devices (audible and visual waveform assessment) were assessed. The reference test was a full lower limb duplex ultrasound. Based on the reference test, 202 (66.2%) patients had evidence of PAD. PAD-scan had a significantly higher sensitivity (95%, CI 90 to 97%) as compared to all other tests. Particularly low sensitivities were seen with pulse palpation (43%, CI 36 to 50%) and TcPO2 (31%, CI 24 to 38%). PAD-scan had a lower specificity (77%, CI 67 to 84%) compared to TBPI (86%, CI 78 to 93%; p