title: Non-invasive assessment of peripheral arterial disease: Automated ankle brachial index measurement and pulse volume analysis compared to duplex scan.
abstract: OBJECTIVE
  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%.
  
  
  CONCLUSIONS
  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.
authors: Cardiff School of Health Sciences, Cardiff Metropolitan University, Cardiff, UK.
authors: Jane Ea
authors: JE
authors: Lewis
authors: Department of Medical Physics, University Hospital of Wales, Cardiff, UK.
authors: Paul
authors: P
authors: Williams
authors: South East Wales Trials Unit, Cardiff University, Cardiff, UK.
authors: Jane H
authors: JH
authors: Davies
keywords: Automated ankle brachial index; lower limb; peripheral arterial disease; pulse volume; pulse volume waveform; ultrasound duplex scan