Diagnostic Accuracy of Point-of-care Tests Used to Detect Arterial Disease in Diabetes

Objective: 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 PAD in diabetes. Background: 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 visualization and more accurate arterial waveform assessment. However, its accuracy has not been previously evaluated. Methods: From March to October 2019, we recruited 305 patients from 2 diabetic foot clinics. The diagnostic performance of ankle-brachial pressure index, toe-brachial pressure index, transcutaneous pressure of oxygen, 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. Results: Based on the reference test, 202 (66.2%) patients had evidence of PAD. PAD-scan had a significantly higher sensitivity [95%, confidence interval (CI) 90%–97%) as compared to all other tests. Particularly low sensitivities were seen with pulse palpation (43%, CI 36%–50%) and transcutaneous pressure of oxygen (31%, CI 24%–38%). PAD-scan had a lower specificity (77%, CI 67%–84%) compared to toe-brachial pressure index (86%, CI 78%–93%; P < 0.001), but not statistically different when compared to all other tests. Conclusions: PAD-scan has superior diagnostic utility and is a valid first line investigation.