title: Carotid artery stenosis: accuracy of noninvasive tests--individual patient data meta-analysis.
abstract: OBJECTIVE
  To find clinically relevant estimates of the accuracy of noninvasive imaging-Doppler ultrasonography (US), computed tomographic (CT) angiography, magnetic resonance (MR) angiography, and contrast material-enhanced MR angiography-in diagnosing both severe and moderate symptomatic carotid artery stenosis; to ascertain the effect of prespecified clinical factors and clinical setting on diagnostic accuracy; and to estimate the probability of agreement between two noninvasive tests.
  
  
  METHODS
  Original principal investigators obtained ethics approval for each data set. All data were anonymized. Individual patient data sets (IPDs) for noninvasive imaging tests were used to determine sensitivity, specificity, and agreement between the tests for symptomatic carotid artery stenosis; to compare ipsilateral with contralateral arteries; to compare IPDs with literature estimates; to compare routine audit and research data; and to determine the effect of age and sex on sensitivity and specificity.
  
  
  RESULTS
  Contrast-enhanced MR angiography was the most accurate (sensitivity, 0.85 [30 of 35]; 95% confidence interval [CI]: 0.69, 0.93; and specificity, 0.85 [67 of 78]; 95% CI: 0.76, 0.92) for 70%-99% symptomatic stenosis. Sensitivity for a 50%-69% stenosis was poor, although data were limited. Sensitivity and specificity were generally lower in the ipsilateral than in the contralateral artery. IPD estimates were lower than literature values. Results of comparison of research with audit-derived data were inconclusive. Neither age nor sex affected accuracy. Agreement was better between two Doppler US tests and between two contrast-enhanced MR angiographic tests than it was between Doppler US and contrast-enhanced MR angiography, except for a 70%-99% symptomatic stenosis.
  
  
  CONCLUSIONS
  Primary studies should distinguish ipsilateral from contralateral arteries and carefully describe the patients' characteristics and study environment. The literature overestimates noninvasive imaging accuracy. More data are needed to inform physicians in routine clinical practice.
authors.affiliation: Division of Clinical Neurosciences, University of Edinburgh, Western General Hospital, Crewe Rd, Edinburgh EH42XU, Scotland. francesca.chappell@ed.ac.uk
authors.forename: Francesca M
authors.initials: FM
authors.lastname: Chappell
authors.forename: Joanna M
authors.initials: JM
authors.lastname: Wardlaw
authors.forename: Gavin R
authors.initials: GR
authors.lastname: Young
authors.forename: Jonathan H
authors.initials: JH
authors.lastname: Gillard
authors.forename: Giles H
authors.initials: GH
authors.lastname: Roditi
authors.forename: Brigitte
authors.initials: B
authors.lastname: Yip
authors.forename: Jill P
authors.initials: JP
authors.lastname: Pell
authors.forename: Peter M
authors.initials: PM
authors.lastname: Rothwell
authors.forename: Martin M
authors.initials: MM
authors.lastname: Brown
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Gough
authors.forename: Marc S
authors.initials: MS
authors.lastname: Randall
mesh_terms: D000792:Angiography / Q000379:methods*; D016893:Carotid Stenosis / Q000175:diagnosis*; D003287:Contrast Media; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media