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Reliability and Change in Erosion Measurements by High-Resolution peripheral Quantitative Computed Tomography in a Longitudinal Dataset of Rheumatoid Arthritis Patients


J Rheumatol. 2020 Sep 15;jrheum.191391. doi: 10.3899/jrheum.191391. Online ahead of print.

Stephanie Finzel 1, Sarah L Manske 1, Cheryl Barnabe 1, Andrew J Burghardt 1, Hubert Marotte 1, Andrea Scharmga 1, Ellen-Margrethe Hauge 1, Roland Chapurlat 1, Klaus Engelke 1, Xiaojuan Li 1, Bente van Teeffelen 1, Philip G Conaghan 1, Kathryn S Stok 1

Author Information

1 Department of Rheumatology and Clinical Immunology, Medical Center - University of Freiburg, Medical Faculty, University of Freiburg, Freiburg, Germany; Department of Medicine 3, FAU University Erlangen-Nürnberg and Universitätsklinikum Erlangen, Erlangen, Germany; Departments of Medicine and Community Health Sciences, Cumming School of Medicine, University of Calgary, Calgary, Canada; Department of Radiology, Cumming School of Medicine, University of Calgary, Calgary, Canada; Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, United States of America; INSERM 1059/SAINBIOSE, Université Jean Monet, Université de Lyon, Saint-Etienne, France, Department of Rheumatology, CHU Saint-Etienne, Saint-Etienne, France, INSERM CIE3 1408, Université de Lyon, Saint-Etienne, France; Maastricht University, Maastricht, The Netherlands; Department of Rheumatology and Department of Clinical Medicine, Aarhus University Hospital and Aarhus University, Aarhus, Denmark; INSERM 1033, Hôpital Edouard Herriot, 69003 Lyon Cedex, Lyon, France; Department of Biomedical Engineering, Cleveland Clinic, Cleveland, United States of America, Department of Biomedical Engineering, Melbourne School of Engineering, The University of Melbourne, Victoria 3010 Australia, Leeds Institute of Rheumatic and Musculoskeletal Medicine, University of Leeds and NIHR Leeds Biomedical Research Centre, Leeds, UK; Institute for Biomechanics, ETH Zurich, Zurich, Switzerland. Funding and conflicts of interest: RELEX-2 was hosted by the University of San Francisco, California, United States of America. The meeting was sponsored in part by Scanco Medical AG. PGC is supported in part by the UK National Institute for Health Research 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. Address correspondence to Dr. med. Stephanie Finzel, Senior Attending Physician, 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: Stephanie.Finzel@uniklinik-freiburg.de.


Objective: The aim of this multi-reader exercise was to assess the reliability and change over time of erosion measurements in rheumatoid arthritis (RA) patients 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 2nd and 3rd digits, blinded to time order. In total, 368 surfaces (23 patients x16 surfaces) were evaluated per time point 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's kappa; change over time was defined by means ± SD of erosion numbers and dimensions.

Results: ICCs 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 (p=0.0001 for erosion numbers, width, and depth in axial plane, and p=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.