title: RESPECT-ED: Rates of Pulmonary Emboli (PE) and Sub-Segmental PE with Modern Computed Tomographic Pulmonary Angiograms in Emergency Departments: A Multi-Center Observational Study Finds Significant Yield Variation, Uncorrelated with Use or Small PE Rates.
abstract: BACKGROUND
  Overuse of CT Pulmonary Angiograms (CTPA) for diagnosing pulmonary embolism (PE), particularly in Emergency Departments (ED), is considered problematic. Marked variations in positive CTPA rates are reported, with American 4-10% yields driving most concerns. Higher resolution CTPA may increase sub-segmental PE (SSPE) diagnoses, which may be up to 40% false positive. Excessive use and false positives could increase harm vs. benefit. These issues have not been systematically examined outside America.
  
  
  OBJECTIVE
  To describe current yield variation and CTPA utilisation in Australasian ED, exploring potential factors correlated with variation.
  
  
  METHODS
  A retrospective multi-centre review of consecutive ED-ordered CTPA using standard radiology reports. ED CTPA report data were inputted onto preformatted data-sheets. The primary outcome was site level yield, analysed both intra-site and against a nominated 15.3% yield. Factors potentially associated with yield were assessed for correlation.
  
  
  RESULTS
  Fourteen radiology departments (15 ED) provided 7077 CTPA data (94% ≥64-slice CT); PE were reported in 1028 (yield 14.6% (95%CI 13.8-15.4%; range 9.3-25.3%; site variation p <0.0001) with four sites significantly below and one above the 15.3% target. Admissions, CTPA usage, PE diagnosis rates and size of PE were uncorrelated with yield. Large PE (≥lobar) were 55% (CI: 52.1-58.2%) and SSPE 8.8% (CI: 7.1-10.5%) of positive scans. CTPA usage (0.2-1.5% adult attendances) was correlated (p<0.006) with PE diagnosis but not SSPE: large PE proportions.
  We found significant intra-site CTPA yield variation within Australasia. Yield was not clearly correlated with CTPA usage or increased small PE rates. Both SSPE and large PE rates were similar to higher yield historical cohorts. CTPA use was considerably below USA 2.5-3% rates. Higher CTPA utilisation was positively correlated with PE diagnoses, but without evidence of increased proportions of small PE. This suggests that increased diagnoses seem to be of clinically relevant sized PE.
authors.affiliation: Discipline of Emergency Medicine, School of Primary, Aboriginal and Rural Health Care, University of Western Australia, Perth, Australia.|Emergency Department, Sir Charles Gairdner Hospital, Perth, Western Australia, Australia.
authors.forename: David
authors.identifier: http://orcid.org/0000-0002-6552-4855
authors.initials: D
authors.lastname: Mountain
authors.affiliation: Emergency Medicine Department, Gold Coast University Hospital, Southport, Queensland, Australia.
authors.forename: Gerben
authors.initials: G
authors.lastname: Keijzers
authors.affiliation: Department of Emergency Medicine, Royal Brisbane and Women's Hospital, Brisbane, Australia.|School of Medicine, University of Queensland, Brisbane, Queensland, Australia.
authors.forename: Kevin
authors.initials: K
authors.lastname: Chu
authors.affiliation: Emergency Medicine, Royal North Shore Hospital, Sydney, New South Wales, Australia.
authors.forename: Anthony
authors.initials: A
authors.lastname: Joseph
authors.affiliation: Pleural Medicine Unit, Institute for Respiratory Health, Perth, Western Australia, Australia Centre for Respiratory Health, School of Medicine & Pharmacology, University of Western Australia, Perth, Western Australia, Australia.|Respiratory Medicine Unit (Research, Pleural Diseases) Sir Charles Gairdner Hospital, Perth, Western Australia, Australia.
authors.forename: Catherine
authors.initials: C
authors.lastname: Read
authors.affiliation: Emergency Medicine, Monash Health, Melbourne, Victoria, Australia.|Department of Medicine, Monash University, Melbourne, Victoria, Australia.
authors.forename: Gabriel
authors.initials: G
authors.lastname: Blecher
authors.affiliation: Emergency Department, The Townsville Hospital, Townsville, Queensland, Australia.
authors.forename: Jeremy
authors.initials: J
authors.lastname: Furyk
authors.affiliation: Statistical Support, Department of Research, Sir Charles Gairdner Hospital, Perth, Western Australia, Australia.|Centre for Applied Statistics, University of Western Australia, Perth, Western Australia, Australia.
authors.forename: Chrianna
authors.initials: C
authors.lastname: Bharat
authors.affiliation: Emergency Department, The Townsville Hospital, Townsville, Queensland, Australia.
authors.forename: Karthik
authors.initials: K
authors.lastname: Velusamy
authors.affiliation: Emergency Department, Nelson Hospital, Nelson, New Zealand.
authors.forename: Andrew
authors.initials: A
authors.lastname: Munro
authors.affiliation: Emergency Medicine, Ipswich Hospital, Ipswich, Queensland, Australia.
authors.forename: Kylie
authors.initials: K
authors.lastname: Baker
authors.affiliation: Emergency Medicine, The Prince Charles Hospital, Brisbane, Queensland, Australia.
authors.forename: Frances
authors.initials: F
authors.lastname: Kinnear
authors.affiliation: Emergency Medicine, Armadale General Hospital, Perth, Western Australia, Australia.
authors.forename: Ahses
authors.initials: A
authors.lastname: Mukherjee
authors.affiliation: Emergency Medicine, Sutherland Hospital and Community Health Centres, Caringbah, Australia.
authors.forename: Gina
authors.initials: G
authors.lastname: Watkins
authors.affiliation: Emergency Department, Box Hill Hospital, Melbourne, Victoria, Australia.
authors.forename: Paul
authors.initials: P
authors.lastname: Buntine
authors.affiliation: Emergency Medicine Research, Princess Alexandra Hospital, Brisbane, Queensland, Australia.
authors.forename: Georgia
authors.initials: G
authors.lastname: Livesay
authors.affiliation: Centre for Clinical Research in Emergency Medicine, Harry Perkins Institute of Medical Research, University of Western Australia, Perth, Australia.|Emergency Department, Royal Perth Hospital, Perth, Australia.
authors.forename: Daniel
authors.initials: D
authors.lastname: Fatovich
mesh_terms: D000792:Angiography / Q000379:methods; D044362:Australasia; D000072226:Computed Tomography Angiography / Q000379:methods; D004636:Emergency Service, Hospital; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011651:Pulmonary Artery / Q000473:pathology; D011655:Pulmonary Embolism / Q000175:diagnosis*; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed / Q000379:methods