title: Assessing structural changes in axial spondyloarthritis using a low-dose biplanar imaging system.
abstract: OBJECTIVE
  Patients with axial SpA experience repeated spine imaging. EOS is a new low-dose imaging system with significantly lower irradiation than conventional radiography (CR). The objective was to explore the EOS performances compared with CR for the classification and follow-up of SpA.
  
  
  METHODS
  We performed an observational, cross-sectional, single-centre study including SpA patients (definite diagnosis by expert opinion) and control patients [definite chronic mechanical low back pain (cLBP)]. All patients underwent pelvic and frontal and lateral CR of the entire spine and two-dimensional (2D) EOS imaging on the same day. Images were blindly assessed for sacroiliitis [modified New York criteria (mNY)] and for ankylosis of the spine [modified Stoke AS Spine Score (mSASSS)]. Global ease of interpretation was rated on a scale of 0-10. The primary outcome was intermodality agreement, with an a priori defined non-inferiority limit of 0.7. Interobserver, intra-observer and intermodality agreement were measured by kappa, weighted kappa, intraclass correlation coefficient and Bland-Altman plots.
  
  
  RESULTS
  Forty-eight SpA patients [mean age 47.6 years (s.d. 14.9), symptom duration 21.4 years (s.d. 13.3), 35 (70%) men] and 48 cLBP controls [mean age 49.1 years (s.d. 10.7), 9 (22.5%) men] were included. Intermodality agreement between EOS and CR was 0.50 (95% CI 0.26, 0.75) and 0.97 (95% CI 0.95, 0.98) for sacroiliitis and mSASSS, respectively. Ease of interpretation was greater for CR [8.2 (s.d. 0.9)] compared with EOS [7.2 (s.d. 0.8), P < 0.0001).
  
  
  CONCLUSIONS
  Our results suggest that EOS could replace CR for the follow-up of structural damage of the spine, but its place in the classification of sacroiliitis needs to be further explored.
authors.affiliation: Rheumatology B Department, Cochin Hospital, Medicine Faculty, APHP, Paris Descartes University, Paris, France, Department of Medicine, Universitat Autònoma de Barcelona, Barcelona, Spain, INSERM (U1153): Clinical Epidemiology and Biostatistics, PRES Sorbonne Paris-Cité, France, Department of Radiology, Centre Hospitalier de l'Université de Montréal, Montréal, QC, Canada, Radiology B Department, Cochin Hospital, Medicine Faculty, APHP, Paris Descartes University, Paris, France and Department of Medicine, University of Alberta, Edmonton, AB, Canada, Physical Medicine and Rehabilitation Department, Cochin Hospital, Paris Descartes University, APHP, Sorbonne Universités, UPMC Univ Paris 06, UMR_S 1136, Institut Pierre Louis d'Epidémiologie et de Santé Publique and AP-HP, Dept of Rheumatology, Pitie Salpetriere University Hospital, Paris, France.Rheumatology B Department, Cochin Hospital, Medicine Faculty, APHP, Paris Descartes University, Paris, France, Department of Medicine, Universitat Autònoma de Barcelona, Barcelona, Spain, INSERM (U1153): Clinical Epidemiology and Biostatistics, PRES Sorbonne Paris-Cité, France, Department of Radiology, Centre Hospitalier de l'Université de Montréal, Montréal, QC, Canada, Radiology B Department, Cochin Hospital, Medicine Faculty, APHP, Paris Descartes University, Paris, France and Department of Medicine, University of Alberta, Edmonton, AB, Canada, Physical Medicine and Rehabilitation Department, Cochin Hospital, Paris Descartes University, APHP, Sorbonne Universités, UPMC Univ Paris 06, UMR_S 1136, Institut Pierre Louis d'Epidémiologie et de Santé Publique and AP-HP, Dept of Rheumatology, Pitie Salpetriere University Hospital, Paris, France.Rheumatology B Department, Cochin Hospital, Medicine Faculty, APHP, Paris Descartes University, Paris, France, Department of Medicine, Universitat Autònoma de Barcelona, Barcelona, Spain, INSERM (U1153): Clinical Epidemiology and Biostatistics, PRES Sorbonne Paris-Cité, Franc
authors.forename: Anna
authors.initials: A
authors.lastname: Moltó
authors.affiliation: Rheumatology B Department, Cochin Hospital, Medicine Faculty, APHP, Paris Descartes University, Paris, France, Department of Medicine, Universitat Autònoma de Barcelona, Barcelona, Spain, INSERM (U1153): Clinical Epidemiology and Biostatistics, PRES Sorbonne Paris-Cité, France, Department of Radiology, Centre Hospitalier de l'Université de Montréal, Montréal, QC, Canada, Radiology B Department, Cochin Hospital, Medicine Faculty, APHP, Paris Descartes University, Paris, France and Department of Medicine, University of Alberta, Edmonton, AB, Canada, Physical Medicine and Rehabilitation Department, Cochin Hospital, Paris Descartes University, APHP, Sorbonne Universités, UPMC Univ Paris 06, UMR_S 1136, Institut Pierre Louis d'Epidémiologie et de Santé Publique and AP-HP, Dept of Rheumatology, Pitie Salpetriere University Hospital, Paris, France.Rheumatology B Department, Cochin Hospital, Medicine Faculty, APHP, Paris Descartes University, Paris, France, Department of Medicine, Universitat Autònoma de Barcelona, Barcelona, Spain, INSERM (U1153): Clinical Epidemiology and Biostatistics, PRES Sorbonne Paris-Cité, France, Department of Radiology, Centre Hospitalier de l'Université de Montréal, Montréal, QC, Canada, Radiology B Department, Cochin Hospital, Medicine Faculty, APHP, Paris Descartes University, Paris, France and Department of Medicine, University of Alberta, Edmonton, AB, Canada, Physical Medicine and Rehabilitation Department, Cochin Hospital, Paris Descartes University, APHP, Sorbonne Universités, UPMC Univ Paris 06, UMR_S 1136, Institut Pierre Louis d'Epidémiologie et de Santé Publique and AP-HP, Dept of Rheumatology, Pitie Salpetriere University Hospital, Paris, France.
authors.forename: Véronique
authors.initials: V
authors.lastname: Freire
authors.affiliation: Rheumatology B Department, Cochin Hospital, Medicine Faculty, APHP, Paris Descartes University, Paris, France, Department of Medicine, Universitat Autònoma de Barcelona, Barcelona, Spain, INSERM (U1153): Clinical Epidemiology and Biostatistics, PRES Sorbonne Paris-Cité, France, Department of Radiology, Centre Hospitalier de l'Université de Montréal, Montréal, QC, Canada, Radiology B Department, Cochin Hospital, Medicine Faculty, APHP, Paris Descartes University, Paris, France and Department of Medicine, University of Alberta, Edmonton, AB, Canada, Physical Medicine and Rehabilitation Department, Cochin Hospital, Paris Descartes University, APHP, Sorbonne Universités, UPMC Univ Paris 06, UMR_S 1136, Institut Pierre Louis d'Epidémiologie et de Santé Publique and AP-HP, Dept of Rheumatology, Pitie Salpetriere University Hospital, Paris, France.
authors.forename: Antoine
authors.initials: A
authors.lastname: Feydy
authors.affiliation: Rheumatology B Department, Cochin Hospital, Medicine Faculty, APHP, Paris Descartes University, Paris, France, Department of Medicine, Universitat Autònoma de Barcelona, Barcelona, Spain, INSERM (U1153): Clinical Epidemiology and Biostatistics, PRES Sorbonne Paris-Cité, France, Department of Radiology, Centre Hospitalier de l'Université de Montréal, Montréal, QC, Canada, Radiology B Department, Cochin Hospital, Medicine Faculty, APHP, Paris Descartes University, Paris, France and Department of Medicine, University of Alberta, Edmonton, AB, Canada, Physical Medicine and Rehabilitation Department, Cochin Hospital, Paris Descartes University, APHP, Sorbonne Universités, UPMC Univ Paris 06, UMR_S 1136, Institut Pierre Louis d'Epidémiologie et de Santé Publique and AP-HP, Dept of Rheumatology, Pitie Salpetriere University Hospital, Paris, France.
authors.forename: Simon
authors.initials: S
authors.lastname: Paternotte
authors.affiliation: Rheumatology B Department, Cochin Hospital, Medicine Faculty, APHP, Paris Descartes University, Paris, France, Department of Medicine, Universitat Autònoma de Barcelona, Barcelona, Spain, INSERM (U1153): Clinical Epidemiology and Biostatistics, PRES Sorbonne Paris-Cité, France, Department of Radiology, Centre Hospitalier de l'Université de Montréal, Montréal, QC, Canada, Radiology B Department, Cochin Hospital, Medicine Faculty, APHP, Paris Descartes University, Paris, France and Department of Medicine, University of Alberta, Edmonton, AB, Canada, Physical Medicine and Rehabilitation Department, Cochin Hospital, Paris Descartes University, APHP, Sorbonne Universités, UPMC Univ Paris 06, UMR_S 1136, Institut Pierre Louis d'Epidémiologie et de Santé Publique and AP-HP, Dept of Rheumatology, Pitie Salpetriere University Hospital, Paris, France.
authors.forename: Walter P
authors.initials: WP
authors.lastname: Maksymowych
authors.affiliation: Rheumatology B Department, Cochin Hospital, Medicine Faculty, APHP, Paris Descartes University, Paris, France, Department of Medicine, Universitat Autònoma de Barcelona, Barcelona, Spain, INSERM (U1153): Clinical Epidemiology and Biostatistics, PRES Sorbonne Paris-Cité, France, Department of Radiology, Centre Hospitalier de l'Université de Montréal, Montréal, QC, Canada, Radiology B Department, Cochin Hospital, Medicine Faculty, APHP, Paris Descartes University, Paris, France and Department of Medicine, University of Alberta, Edmonton, AB, Canada, Physical Medicine and Rehabilitation Department, Cochin Hospital, Paris Descartes University, APHP, Sorbonne Universités, UPMC Univ Paris 06, UMR_S 1136, Institut Pierre Louis d'Epidémiologie et de Santé Publique and AP-HP, Dept of Rheumatology, Pitie Salpetriere University Hospital, Paris, France.
authors.forename: Mathilde
authors.initials: M
authors.lastname: Benhamou
authors.affiliation: Rheumatology B Department, Cochin Hospital, Medicine Faculty, APHP, Paris Descartes University, Paris, France, Department of Medicine, Universitat Autònoma de Barcelona, Barcelona, Spain, INSERM (U1153): Clinical Epidemiology and Biostatistics, PRES Sorbonne Paris-Cité, France, Department of Radiology, Centre Hospitalier de l'Université de Montréal, Montréal, QC, Canada, Radiology B Department, Cochin Hospital, Medicine Faculty, APHP, Paris Descartes University, Paris, France and Department of Medicine, University of Alberta, Edmonton, AB, Canada, Physical Medicine and Rehabilitation Department, Cochin Hospital, Paris Descartes University, APHP, Sorbonne Universités, UPMC Univ Paris 06, UMR_S 1136, Institut Pierre Louis d'Epidémiologie et de Santé Publique and AP-HP, Dept of Rheumatology, Pitie Salpetriere University Hospital, Paris, France.
authors.forename: François
authors.initials: F
authors.lastname: Rannou
authors.affiliation: Rheumatology B Department, Cochin Hospital, Medicine Faculty, APHP, Paris Descartes University, Paris, France, Department of Medicine, Universitat Autònoma de Barcelona, Barcelona, Spain, INSERM (U1153): Clinical Epidemiology and Biostatistics, PRES Sorbonne Paris-Cité, France, Department of Radiology, Centre Hospitalier de l'Université de Montréal, Montréal, QC, Canada, Radiology B Department, Cochin Hospital, Medicine Faculty, APHP, Paris Descartes University, Paris, France and Department of Medicine, University of Alberta, Edmonton, AB, Canada, Physical Medicine and Rehabilitation Department, Cochin Hospital, Paris Descartes University, APHP, Sorbonne Universités, UPMC Univ Paris 06, UMR_S 1136, Institut Pierre Louis d'Epidémiologie et de Santé Publique and AP-HP, Dept of Rheumatology, Pitie Salpetriere University Hospital, Paris, France.Rheumatology B Department, Cochin Hospital, Medicine Faculty, APHP, Paris Descartes University, Paris, France, Department of Medicine, Universitat Autònoma de Barcelona, Barcelona, Spain, INSERM (U1153): Clinical Epidemiology and Biostatistics, PRES Sorbonne Paris-Cité, France, Department of Radiology, Centre Hospitalier de l'Université de Montréal, Montréal, QC, Canada, Radiology B Department, Cochin Hospital, Medicine Faculty, APHP, Paris Descartes University, Paris, France and Department of Medicine, University of Alberta, Edmonton, AB, Canada, Physical Medicine and Rehabilitation Department, Cochin Hospital, Paris Descartes University, APHP, Sorbonne Universités, UPMC Univ Paris 06, UMR_S 1136, Institut Pierre Louis d'Epidémiologie et de Santé Publique and AP-HP, Dept of Rheumatology, Pitie Salpetriere University Hospital, Paris, France.
authors.forename: Maxime
authors.initials: M
authors.lastname: Dougados
authors.affiliation: Rheumatology B Department, Cochin Hospital, Medicine Faculty, APHP, Paris Descartes University, Paris, France, Department of Medicine, Universitat Autònoma de Barcelona, Barcelona, Spain, INSERM (U1153): Clinical Epidemiology and Biostatistics, PRES Sorbonne Paris-Cité, France, Department of Radiology, Centre Hospitalier de l'Université de Montréal, Montréal, QC, Canada, Radiology B Department, Cochin Hospital, Medicine Faculty, APHP, Paris Descartes University, Paris, France and Department of Medicine, University of Alberta, Edmonton, AB, Canada, Physical Medicine and Rehabilitation Department, Cochin Hospital, Paris Descartes University, APHP, Sorbonne Universités, UPMC Univ Paris 06, UMR_S 1136, Institut Pierre Louis d'Epidémiologie et de Santé Publique and AP-HP, Dept of Rheumatology, Pitie Salpetriere University Hospital, Paris, France.Rheumatology B Department, Cochin Hospital, Medicine Faculty, APHP, Paris Descartes University, Paris, France, Department of Medicine, Universitat Autònoma de Barcelona, Barcelona, Spain, INSERM (U1153): Clinical Epidemiology and Biostatistics, PRES Sorbonne Paris-Cité, France, Department of Radiology, Centre Hospitalier de l'Université de Montréal, Montréal, QC, Canada, Radiology B Department, Cochin Hospital, Medicine Faculty, APHP, Paris Descartes University, Paris, France and Department of Medicine, University of Alberta, Edmonton, AB, Canada, Physical Medicine and Rehabilitation Department, Cochin Hospital, Paris Descartes University, APHP, Sorbonne Universités, UPMC Univ Paris 06, UMR_S 1136, Institut Pierre Louis d'Epidémiologie et de Santé Publique and AP-HP, Dept of Rheumatology, Pitie Salpetriere University Hospital, Paris, France.Rheumatology B Department, Cochin Hospital, Medicine Faculty, APHP, Paris Descartes University, Paris, France, Department of Medicine, Universitat Autònoma de Barcelona, Barcelona, Spain, INSERM (U1153): Clinical Epidemiology and Biostatistics, PRES Sorbonne Paris-Cité, Franc
authors.forename: Laure
authors.initials: L
authors.lastname: Gossec
mesh_terms: D000328:Adult; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D017116:Low Back Pain / Q000000981:diagnostic imaging; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D011829:Radiation Dosage; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods; D015203:Reproducibility of Results; D012446:Sacroiliac Joint / Q000000981:diagnostic imaging; D058566:Sacroiliitis / Q000000981:diagnostic imaging; D012720:Severity of Illness Index; D025241:Spondylarthritis / Q000000981:diagnostic imaging*
keywords: EOS; ankylosis; radiography; sacroiliitis; spondyloarthritis; syndesmophytes