title: Pre-test probability of obstructive coronary stenosis in patients undergoing coronary CT angiography: Comparative performance of the modified diamond-Forrester algorithm versus methods incorporating cardiovascular risk factors.
abstract: BACKGROUND
  Current guidelines recommend the use of the Modified Diamond-Forrester (MDF) method to assess the pre-test likelihood of obstructive coronary artery disease (CAD). We aimed to compare the performance of the MDF method with two contemporary algorithms derived from multicenter trials that additionally incorporate cardiovascular risk factors: the calculator-based 'CAD Consortium 2' method, and the integer-based CONFIRM score.
  
  
  METHODS
  We assessed 1069 consecutive patients without known CAD undergoing coronary CT angiography (CCTA) for stable chest pain. Obstructive CAD was defined as the presence of coronary stenosis ≥50% on 64-slice dual-source CT. The three methods were assessed for calibration, discrimination, net reclassification, and changes in proposed downstream testing based upon calculated pre-test likelihoods.
  
  
  RESULTS
  The observed prevalence of obstructive CAD was 13.8% (n=147). Overestimations of the likelihood of obstructive CAD were 140.1%, 9.8%, and 18.8%, respectively, for the MDF, CAD Consortium 2 and CONFIRM methods. The CAD Consortium 2 showed greater discriminative power than the MDF method, with a C-statistic of 0.73 vs. 0.70 (p<0.001), while the CONFIRM score did not (C-statistic 0.71, p=0.492). Reclassification of pre-test likelihood using the 'CAD Consortium 2' or CONFIRM scores resulted in a net reclassification improvement of 0.19 and 0.18, respectively, which would change the diagnostic strategy in approximately half of the patients.
  
  
  CONCLUSIONS
  Newer risk factor-encompassing models allow for a more precise estimation of pre-test probabilities of obstructive CAD than the guideline-recommended MDF method. Adoption of these scores may improve disease prediction and change the diagnostic pathway in a significant proportion of patients.
authors: Cardiovascular Imaging Unit, Hospital da Luz, Avenida Lusíada 100, Lisbon, Portugal; Cardiology Department, Carnaxide, Portugal. Electronic address: antonio.ferreira@hospitaldaluz.pt.
authors: António Miguel
authors: AM
authors: Ferreira
authors: Cardiovascular Imaging Unit, Hospital da Luz, Avenida Lusíada 100, Lisbon, Portugal.
authors: Hugo
authors: H
authors: Marques
authors: Cardiovascular Imaging Unit, Hospital da Luz, Avenida Lusíada 100, Lisbon, Portugal; Cardiology Department, Carnaxide, Portugal.
authors: António
authors: A
authors: Tralhão
authors: Cardiovascular Imaging Unit, Hospital da Luz, Avenida Lusíada 100, Lisbon, Portugal; Cardiology Department, Carnaxide, Portugal.
authors: Miguel Borges
authors: MB
authors: Santos
authors: Cardiovascular Imaging Unit, Hospital da Luz, Avenida Lusíada 100, Lisbon, Portugal; Cardiology Department, Hospital Distrital de Évora, Largo Senhor da Pobreza, Évora, Portugal.
authors: Ana Rita
authors: AR
authors: Santos
authors: Cardiovascular Imaging Unit, Hospital da Luz, Avenida Lusíada 100, Lisbon, Portugal; Cardiology Department, Carnaxide, Portugal.
authors: Gonçalo
authors: G
authors: Cardoso
authors: Cardiovascular Imaging Unit, Hospital da Luz, Avenida Lusíada 100, Lisbon, Portugal; Cardiology Department, Carnaxide, Portugal.
authors: Hélder
authors: H
authors: Dores
authors: Cardiovascular Imaging Unit, Hospital da Luz, Avenida Lusíada 100, Lisbon, Portugal; Cardiology Department, Carnaxide, Portugal.
authors: Maria Salomé
authors: MS
authors: Carvalho
authors: Cardiovascular Imaging Unit, Hospital da Luz, Avenida Lusíada 100, Lisbon, Portugal; Cardiology Department, Carnaxide, Portugal.
authors: Sérgio
authors: S
authors: Madeira
authors: Cardiovascular Imaging Unit, Hospital da Luz, Avenida Lusíada 100, Lisbon, Portugal.
authors: Francisco Pereira
authors: FP
authors: Machado
authors: Cardiovascular Imaging Unit, Hospital da Luz, Avenida Lusíada 100, Lisbon, Portugal.
authors: Nuno
authors: N
authors: Cardim
authors: Cardiovascular Imaging Unit, Hospital da Luz, Avenida Lusíada 100, Lisbon, Portugal; Cardiology Department, Carnaxide, Portugal; CEDOC, Chronic Diseases Research Center, FCM-NOVA, Lisbon, Portugal.
authors: Pedro
authors: P
authors: de Araújo Gonçalves
mesh_terms: D000368:Aged; D000465:Algorithms; D000072226:Computed Tomography Angiography / Q000379:methods* / Q000592:standards; D017023:Coronary Angiography / Q000379:methods* / Q000592:standards; D023921:Coronary Stenosis / Q000000981:diagnostic imaging* / Q000503:physiopathology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012307:Risk Factors
keywords: Coronary CT angiography; Coronary artery disease; Diagnosis; Pre-test probability; Validation