title: Comparative accuracy of renal duplex sonographic parameters in the diagnosis of renal artery stenosis: paired and unpaired analysis.
abstract: OBJECTIVE
  The purpose of this study was to evaluate the test performance of duplex sonographic parameters in screening for hemodynamically significant renal artery stenosis, which occurs in approximately 5% of persons with hypertension.
  
  
  METHODS
  A comprehensive literature search was conducted to find studies on the diagnosis of renal artery stenosis in which duplex sonography and intraarterial angiography were compared and in which sensitivity and specificity were calculated. MEDLINE (1966-2005), EMBASE (1988-2005), and reference lists were searched and the authors contacted. Data were subjected to meta-analysis according to the hierarchical summary receiver operating characteristic curve model. Heterogeneity in test performance relating to population and design features was investigated.
  
  
  RESULTS
  From 1,357 titles, 88 studies involving 9,974 arteries in 8,147 patients were included. The following four parameters were evaluated: peak systolic velocity (21 studies), acceleration time (13 studies), acceleration index (13 studies), and renal-aortic ratio (13 studies). The corresponding diagnostic odds ratios (ORs) were 60.9 (95% CI, 28.3-131.2), 28.9 (95% CI, 7.1-117.2), 16.0 (95% CI, 5.1-50.6), and 29.3 (95% CI, 12.7-67.7). Results based on studies in which parameters were directly compared showed that peak systolic velocity had greater accuracy than renal-aortic ratio (relative diagnostic OR, 1.8; p = 0.03; nine studies) and acceleration index (relative diagnostic OR, 5.3; p < 0.001; five studies). Acceleration time versus acceleration index showed no evidence of a difference in accuracy (relative diagnostic OR, 1.1; p = 0.65; nine studies). Analysis of peak systolic velocity used in combination with other parameters compared with peak systolic velocity alone (seven studies) showed evidence of a shift in test positivity (p < 0.001) but only weak evidence of improvement in accuracy (relative diagnostic OR, 1.6; p = 0.09).
  
  
  CONCLUSIONS
  Sonography is a moderately accurate screening test for renal artery stenosis. The single measurement, peak systolic velocity, has the highest performance characteristics, an expected sensitivity of 85% and specificity of 92%. Additional measurements do not increase accuracy.
authors.affiliation: Centre for Kidney Research and Department of Nephrology, Children's Hospital at Westmead, Hawkesbury Rd. (Locked Bag 4001) Westmead, New South Wales 2145, Australia. Gabriew4@chw.edu.au
authors.forename: Gabrielle J
authors.initials: GJ
authors.lastname: Williams
authors.forename: Petra
authors.initials: P
authors.lastname: Macaskill
authors.forename: Siew F
authors.initials: SF
authors.lastname: Chan
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Karplus
authors.forename: Winkle
authors.initials: W
authors.lastname: Yung
authors.forename: Elisabeth M
authors.initials: EM
authors.lastname: Hodson
authors.forename: Jonathan C
authors.initials: JC
authors.lastname: Craig
mesh_terms: D015331:Cohort Studies; D006801:Humans; D012078:Renal Artery Obstruction / Q000000981:diagnostic imaging* / Q000453:epidemiology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D018616:Ultrasonography, Doppler, Duplex / Q000706:statistics & numerical data*