Diagnostic Test Accuracy of Pedal Acceleration Time to Identify Peripheral Artery Disease.

Abstract

Objective: Pedal acceleration time (PAT) is a novel method of using diagnostic ultrasound to evaluate the haemodynamic characteristics of pedal arteries and has potential as an adjunct vascular testing method. The primary objective of this study was to assess the diagnostic accuracy of PAT in identifying peripheral artery disease (PAD) in a population with clinically suspected PAD.

Methods: This was a multicentre cross sectional study to estimate the diagnostic test accuracy. Participants with clinically suspected PAD were recruited via consecutive sampling at four centres. Colour duplex ultrasound (reference standard) and toe brachial index (TBI) were measured by a vascular sonographer. A second vascular sonographer, blinded to all other measures, conducted the PAT measurements on the same limb. PAD was defined as a > 50% stenosis in any vessel from the distal aorta to the foot. Sensitivity, specificity, positive and negative predictive values, and positive and negative likelihood ratios were estimated for all PAT values. Receiver operating characteristic curves were also generated.

Results: 188 participants (227 limbs) were recruited, with a mean age of 71 years (standard deviation 10, range 43 - 93) with 56 women (30%) including 133 limbs having PAD (59%) and 61 (33%) claudicants. Area under the curve for PAT: lateral plantar artery 0.72 (0.65 - 0.79), medial plantar artery 0.72 (0.65 - 0.79), dorsal metatarsal artery 0.77 (0.70 - 0.84), arcuate artery 0.71 (0.64 - 0.78), and deep plantar artery 0.73 (0.67 - 0.80). Utilising the worst case PAT measure for the limb for identifying PAD had an AUC of 0.79 (0.74 - 0.85) and positive and negative predictive values of 0.81 (0.57 - 0.89) and 0.66 (0.57 - 0.75), respectively. Area under the curve for the toe brachial index was 0.78 (0.71 - 0.85) and that of ankle brachial index was 0.70 (0.62 - 0.77).

Conclusion: PAT exhibited an acceptable diagnostic test accuracy as an assessment tool to identify PAD in a population with clinically suspected PAD. All five measures yielded similar accuracy to toe pressure and TBI; however, utilising the worst case PAT value yielded the highest diagnostic test accuracy of all PAT measures. The PAT diagnostic threshold for the presence of PAD may be revised to > 85 ms to optimise the performance of the test for the identification of PAD.