title: Ethnicity as an independent predictive factor for the results of computed tomography pulmonary angiography and ultrasonography of the lower limbs.
abstract: BACKGROUND
  Asians, Pacific Islanders and Maori have significantly lower rates of venous thromboembolism (VTE) compared to Europeans, but its clinic implication regarding diagnosis and prevention is unclear.
  
  
  OBJECTIVE
  To investigate if ethnicity affects the yield of computed tomography pulmonary angiography (CTPA) and ultrasonography of the lower limbs.
  
  
  METHODS
  Data previously collected for 523 patients from another study were used to analyse the effect of ethnicity on the results of CTPA; 1587 consecutive ultrasonography of lower limbs was retrospectively analysed according to ethnicity. The Wells score was retrospectively calculated to determine the pretest probability of VTE.
  
  
  RESULTS
  The positive rates of CTPA were 23.3% for European patients and 9.3% for non-European patients. The rate ratio was 2.50 (confidence interval [CI] 1.27-4.95). European patients were 2.5 times more likely to have a positive scan result than non-Europeans, given same pretest probability. There was a larger difference among patients with low and moderate pretest probability with a rate ratio of 4.27 (CI 1.62-11.3). The positive rates of ultrasound scans (USS) among European patients were 16.6 and 9.0% for non-European patients. Rate ratio was 1.85 (CI 1.27-4.95). The difference was also more significant amongst patients with low and moderate pretest probability. The rate ratio was 2.31 (CI 1.38-3.86) for European patients compared to non-European patients.
  
  
  CONCLUSIONS
  Given the same pretest probability according to the Wells score, European patients had significantly higher positive rates of CTPA and ultrasonography of the lower limbs than non-European patients. Further prospective studies are required to confirm our findings and establish an appropriate pretest assessment tool for non-European patients.
authors.affiliation: Department of Aged Care, The Royal Melbourne Hospital, Melbourne, Victoria, Australia.
authors.forename: S
authors.initials: S
authors.lastname: Liao
authors.affiliation: Department of Radiology, Waikato Hospital, Hamilton, New Zealand.
authors.forename: K
authors.initials: K
authors.lastname: McAnulty
authors.affiliation: Department of General Medicine, Waikato Hospital, Hamilton, New Zealand.
authors.forename: C
authors.initials: C
authors.lastname: Lim
authors.affiliation: Department of General Medicine, Waikato Hospital, Hamilton, New Zealand.
authors.forename: P
authors.initials: P
authors.lastname: Reeve
authors.affiliation: Department of Respiratory Medicine, Waikato Hospital, Hamilton, New Zealand.
authors.forename: C L
authors.initials: CL
authors.lastname: Chang
mesh_terms: D001315:Australia; D000072226:Computed Tomography Angiography; D005006:Ethnicity; D006801:Humans; D016015:Logistic Models; D035002:Lower Extremity / Q000000981:diagnostic imaging; D011336:Probability; D011655:Pulmonary Embolism / Q000000981:diagnostic imaging* / Q000208:ethnology*; D012189:Retrospective Studies; D014463:Ultrasonography; D054556:Venous Thromboembolism / Q000000981:diagnostic imaging* / Q000208:ethnology*
keywords: X-ray computed tomography; angiography; pulmonary embolism; ultrasonography; venous thrombosis