title: Diagnostic utility of the two methods of ankle brachial index in the detection of peripheral arterial disease of lower extremities.
abstract: BACKGROUND
  Peripheral arterial disease (PAD) is a common disease that is diagnosed with a screening test called the Ankle Brachial Index (ABI). Different methods of ABI have been described in the literature. We wanted to estimate and compare the sensitivity and specificity of an alternative method of calculating the ABI (LAP ABI, low ankle pressure ABI) with the current method (named high ankle pressure (HAP)), using digital subtraction angiography (DSA) as the gold standard.
  
  
  METHODS
  We reviewed the records of all patients who had undergone DSA at a major academic center between August 2003 and October 2005. The study includes 107 patients/208 limbs. Inclusion criteria included patients with an ABI performed within 30 days prior to the DSA. Patients with non-compressible vessels and ABI >1.40 were excluded. Abnormal ABI was defined as < or = 0.9 for both methods. Disease on angiogram was defined as the presence of 50% or more stenosis of any lower extremity artery from the aorto-iliac bifurcation to the ankle arteries.
  
  
  RESULTS
  The sensitivity of the HAP and LAP ABI for the diagnosis of PAD was 69 and 84%, respectively (P < 0.001). The specificity of the HAP and the LAP method was 83 and 64% respectively (P < 0.01). The overall accuracy of LAP ABI and HAP ABI was 80 and 72%, respectively.
  
  
  CONCLUSIONS
  The LAP ABI has better sensitivity and overall accuracy in comparison to the HAP ABI to diagnose PAD.
authors.affiliation: Division of Cardiology, Emory Crawford Long Hospital, Emory University School of Medicine, Atlanta, Georgia 30308, USA. Tahir.Khan@Emoryhealthcare.org
authors.forename: Khusrow
authors.initials: K
authors.lastname: Niazi
authors.forename: Tahir H
authors.initials: TH
authors.lastname: Khan
authors.forename: Kirk A
authors.initials: KA
authors.lastname: Easley
mesh_terms: D000368:Aged; D015901:Angiography, Digital Subtraction; D000842:Ankle / Q000098:blood supply / Q000000981:diagnostic imaging; D001157:Arterial Occlusive Diseases / Q000503:physiopathology; D001794:Blood Pressure; D001916:Brachial Artery / Q000503:physiopathology*; D005188:False Negative Reactions; D005260:Female; D006801:Humans; D035002:Lower Extremity / Q000098:blood supply* / Q000000981:diagnostic imaging; D008297:Male; D016491:Peripheral Vascular Diseases / Q000000981:diagnostic imaging / Q000503:physiopathology*; D012107:Research Design; D012189:Retrospective Studies; D012680:Sensitivity and Specificity