title: Diagnostic accuracy of laser Doppler flowmetry versus strain gauge plethysmography for segmental pressure measurement.
abstract: OBJECTIVE
  To assess the diagnostic accuracy of laser Doppler flowmetry (LDF) with mercury-in-silastic strain gauge plethysmography (SGP) as a reference test for measuring the toe and ankle pressures in patients with known or suspected peripheral arterial disease (PAD).
  
  
  METHODS
  This was a prospective, randomized, blinded diagnostic accuracy study. Toe and ankle pressures were measured using both methods in 200 consecutive patients, who were recruited at our vascular laboratory over a period of 30 working days. Classification of PAD and critical limb ischemia (CLI) was made in accordance with TASC-II criteria.
  
  
  RESULTS
  The LDF method demonstrated 5.8 mm Hg higher mean toe pressures than the SGP method for the right limb and 7.0 mm Hg for the left limb (both P < .001). There were no significant differences in the mean ankle pressures (both P > .129). The limits of agreement for the differences (SGP - LDF) were -31.7 to 20.2 mm Hg for right toe pressures, -28.0 to 14.0 mm Hg for left toe pressures, -25.5 to 22.8 mm Hg for right ankle pressures, and -26.9 to 24.6 mm Hg for left ankle pressures. A correlation analysis of the absolute pressures using the two methods showed an intraclass correlation coefficient of 0.902 (95% confidence interval [CI], 0.835-0.938) for right toe pressures, 0.919 (95% CI, 0.782-0.960) for the left toe pressures, 0.953 (95% CI, 0.937-0.965) for right ankle pressures, and 0.952 (95% CI, 0.936-0.964) for left ankle pressures. Cohen's Kappa showed an agreement in the diagnostic classification of κ = 0.775 (95% CI, 0.631-0.919) for PAD and κ = 0.780 (95% CI, 0.624-0.936) for CLI.
  
  
  CONCLUSIONS
  LDF showed a good correlation with SGP over a wide range of toe and ankle pressures, as well as substantial agreement for the diagnostic classification of PAD including CLI.
authors.affiliation: Department of Clinical Physiology, Viborg Regional Hospital, Viborg, Denmark; Department of Health Science and Technology, Aalborg University, Aalborg, Denmark. Electronic address: ch@hst.aau.dk.
authors.forename: Christian
authors.initials: C
authors.lastname: Høyer
authors.forename: Jes
authors.initials: J
authors.lastname: Sandermann
authors.forename: Jens Peder D
authors.initials: JP
authors.lastname: Paludan
authors.forename: Susanne
authors.initials: S
authors.lastname: Pavar
authors.forename: Lars J
authors.initials: LJ
authors.lastname: Petersen
mesh_terms: D000368:Aged; D004311:Double-Blind Method; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D017078:Laser-Doppler Flowmetry / Q000379:methods*; D007866:Leg / Q000098:blood supply*; D008297:Male; D058729:Peripheral Arterial Disease / Q000175:diagnosis* / Q000503:physiopathology; D010992:Plethysmography, Impedance / Q000379:methods; D011379:Prognosis; D011446:Prospective Studies; D015203:Reproducibility of Results; D012720:Severity of Illness Index