Non-invasive assessment of peripheral arterial disease: Automated ankle brachial index measurement and pulse volume analysis compared to duplex scan

 Objectives: This cross-sectional study aimed to individually and cumulatively compare sensitivity and specificity of the (1) ankle brachial index and (2) pulse volume waveform analysis recorded by the same automated device, with the presence or absence of peripheral arterial disease being verified by ultrasound duplex scan.Methods: Patients (n=205) referred for lower limb arterial assessment underwent ankle brachial index measurement and pulse  volume  waveform  recording  using  volume  plethysmography,  followed  by  ultrasound  duplex  scan.  The  presence  of  peripheral arterial disease was recorded if ankle brachial index <0.9; pulse volume waveform was graded as 2, 3 or 4; or if haemodynamically significant stenosis >50% was evident with ultrasound duplex scan. Outcome measure was agreement between  the  measured  ankle  brachial  index  and  interpretation  of  pulse  volume  waveform  for  peripheral  arterial  disease  diagnosis, using ultrasound duplex scan as the reference standard.Results: Sensitivity  of  ankle  brachial  index  was  79%,  specificity  91%  and  overall  accuracy  88%.  Pulse  volume  waveform  sensitivity  was  97%,  specificity  81%  and  overall  accuracy  85%.  The  combined  sensitivity  of  ankle  brachial  index  and  pulse  volume waveform was 100%, specificity 76% and overall accuracy 85%.Conclusion: Combining these two diagnostic modalities within one device provided a highly accurate method of ruling out peripheral arterial disease, which could be utilised in primary care to safely reduce unnecessary secondary care referrals.