J Rheumatol 2020 Sep 15. Epub 2020 Sep 15.
RELEX-2 was hosted by the University of San Francisco, California, USA. The meeting was sponsored in part by Scanco Medical AG. PGC is supported in part by the UK National Institute for Health Research (NIHR) Leeds Biomedical Research Centre. The views expressed are those of the authors and not necessarily those of the NIHR or the Department of Health and Social Care. S. Finzel, MD, Senior Attending Physician, Department of Rheumatology and Clinical Immunology, Medical Center - University of Freiburg, Medical Faculty, University of Freiburg, Freiburg, Germany; S.L. Manske, PhD, Assistant Professor, Department of Radiology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada; C.C. Barnabe, MD, MSc, Associate Professor, Departments of Medicine and Community Health Sciences, University of Calgary, and McCaig Institute for Bone and Joint Health, University of Calgary, Calgary, Alberta, Canada; A.J. Burghardt, BS, Research Specialist, Department of Radiology and Biomedical Imaging, University of California San Francisco, California, USA; H. Marotte, MD, PhD, Professor, INSERM 1059, Université de Lyon, and Service de Rhumatologie, CHU de Saint-Etienne, Saint-Etienne, France; A. Scharmga, PhD, Maastricht University, Maastricht, the Netherlands; E.M. Hauge, MD, PhD, Professor, Department of Rheumatology, Aarhus University Hospital and Department of Clinical Medicine, Aarhus University, Aarhus, Denmark; R. Chapurlat, MD, PhD, Professor, INSERM 1033, Hôpital Edouard Herriot, Lyon, France; K. Engelke, PhD, Professor, Department of Medicine 3, FAU University Erlangen-Nürnberg and Universitätsklinikum Erlangen, Erlangen, Germany; X. Li, PhD, Professor, Department of Biomedical Engineering, Cleveland Clinic, Cleveland, Ohio, USA; B.C. van Teeffelen, Department of Biomedical Engineering, Melbourne School of Engineering, The University of Melbourne, Melbourne, Australia; P.G. Conaghan, MD, PhD, Professor, Leeds Institute of Rheumatic and Musculoskeletal Medicine, University of Leeds and NIHR Leeds Biomedical Research Centre, Leeds, UK; K.S. Stok, PhD, Senior Lecturer, Institute for Biomechanics, ETH Zurich, Zurich, Switzerland, and Department of Biomedical Engineering, University of Melbourne, Melbourne, Australia. The authors state that they have no conflicts of interest. Address correspondence to Dr. S. Finzel, Head of Clinical Trials Unit Rheumatology, Department of Rheumatology and Clinical Immunology, University Medical Center, Medical Faculty, University of Freiburg, Hugstetter Strasse 55, 79110 Freiburg, Germany. Email: Accepted for publication September 5, 2020.
Objective: The aim of this multireader exercise was to assess the reliability and change over time of erosion measurements in patients with rheumatoid arthritis (RA) using high-resolution peripheral quantitative computed tomography (HR-pQCT).
Methods: HR-pQCT scans of 23 patients with RA were assessed at baseline and 12 months. Four experienced readers examined the dorsal, palmar, radial, and ulnar surfaces of the metacarpal head (MH) and phalangeal base (PB) of the second and third digits, blinded to time order. In total, 368 surfaces (23 patients´ 16 surfaces) were evaluated per timepoint to characterize cortical breaks as pathological (erosion) or physiological, and to quantify erosion width and depth. Reliability was evaluated by intraclass correlation coefficients (ICC), percentage agreement, and Light k; change over time was defined by means ± SD of erosion numbers and dimensions.
Results: ICC for the mean measurements of width and depth of the pathological breaks ranged between 0.819-0.883, and 0.771-0.907, respectively. Most physiological cortical breaks were found at the palmar PB, whereas most pathological cortical breaks were located at the radial MH. There was a significant increase in both the numbers and the dimensions of erosions between baseline and follow-up ( = 0.0001 for erosion numbers, width, and depth in axial plane; = 0.001 for depth in perpendicular plane).
Conclusion: This exercise confirmed good reliability of HR-pQCT erosion measurements and their ability to detect change over time.