AN ULTRASOUND SCORING SYSTEM BASED ON THE SIZE AND NUMBER OF EROSIONS IS RELIABLE IN RHEUMATOID ARTHRITIS

P. Mandl, I. Gessl, G. Filippou, S. Sirotti, L. Terslev, C. Pineda, E. Cipolletta, P. Collado, C. Dejaco, A. Delle Sedie, C. Duftner, H. B. Hammer, A. Iagnocco, I. Möller, E. Naredo, M. Szkudlarek, G. Tamborrini, R. Wakefield, P. Wong, E. Filippucci, P. Balint, M. A. D’agostinoMedical University of Vienna, Rheumatology, Vienna, Austria IRCCS Ospedale Galeazzi – Sant’Ambrogio, Rheumatology Department, Milan, Italy Copenhagen University Hospital Glostrup, Center for Rheumatology and Spine Diseases, Copenhagen, Denmark Instituto Nacional de Rehabilitación, -, Mexico City, Mexico Polytechnic University of Marche, Rheumatology Unit, Department of Clinical and Molecular Sciences, Jesi, Italy Hospital Universitario Severo Ochoa, Rheumatology, Madrid, Spain Hospital of Brunico (SABES-ASDAA), Department of Rheumatology, Brunico, Italy Medical University Graz, Rheumatology and Immunology, Graz, Austria University of Pisa, Rheumatology Unit, Pisa, Italy Clinical Division of Internal Medicine II, Medical University of Innsbruck, Department of Internal Medicine, Innsbruck, Austria Center for treatment of Rheumatic and Musculoskeletal Diseases (REMEDY), Department of Rheumatology, Oslo, Norway University of Oslo, Faculty of Medicine, Oslo, Norway University of Turin, Academic Rheumatology Centre, Department of Clinical and Biological Science, Turin, Italy Universitat de Barcelona, Instituto Poal de Reumatologia, Barcelona, Spain Hospital Universitario Fundación Jiménez Díaz, IIS Fundación Jiménez Díaz, Department of Rheumatology and Bone and Joint Research Unit, Madrid, Spain Copenhagen University Hospital at Køge, Department of Rheumatology, Copenhagen, Denmark Ultrasound Center and Institute for Rheumatology, -, Basel, Switzerland University of Leeds and Leeds Biomedical Research Centre, Leeds Teaching Hospitals Trust, Chapel Allerton Hospital, Leeds Institute of Rheumatic and Musculoskeletal Medicine, Leeds, United Kingdom The Chinese University of Hong Kong, Hong Kong (SAR), Division of Rheumatology, Department of Medicine and Therapeutics, Hong Kong, Hong Kong (SAR) National Institute of Musculoskeletal Diseases, 3rd Rheumatology Department, Budapest, Hungary Università Cattolica del Sacro Cuore, Fondazione Policlinico Universitario Agostino Gemelli IRCSS, Rheumatology Unit, Rome, Italy  Background Ultrasound has been shown to be a valid tool for the evaluation of bone erosions in rheumatoid arthritis (RA), yet a consensual scoring system is lacking. Objectives To assess the reliability of a semiquantitative scoring system for assessing structural bone erosion by ultrasound in a web-based reliability exercise. Methods A task force of the OMERACT Ultrasound Working Group developed definitions and a scoring system for grading bone erosions which takes both the size and number of erosions into consideration. Pairs of static images (longitudinal and transverse) in DICOM format of metacarpophalangeal and proximal interphalangeal joints 2-5 were acquired prospectively in healthy controls and in RA patients with varying degrees of pathology by the task force members. A dataset of anonymized images, representing various grades was created and utilized in a web-based exercise using the cmrad.com cloud platform which allowed the participants to measure the size of the erosions and use the discrete measures and the number of erosions to grade each joint according to the scoring system. Both the longitudinal and transverse scans were considered and the largest diameter chosen for each erosion. Intra- and inter-reader reliability of the scoring system was assessed using kappa statistics. Results A 4-grade semiquantitative scoring system was developed: grade 0) intact cortical bone; grade 1) single small erosion (diameter: ≤2mm); grade 2) single large erosion (diameter: >2mm) or 2 small erosions or 1 large and 1 small erosion; grade 3) 2 large erosions or ≥3 erosions, regardless of size (Figure 1). A dataset composed of 45 anonymised image pairs (90 single images) was graded by 20 task force members in two rounds separated by 10 days. The intra-reader (mean: 0.79; 95% confidence interval: 0.75-0.84) reliability was excellent and the inter-reader (mean: 0.75; 95% confidence interval: 0.74-0.76) reliability was substantial. Conclusion This preliminary OMERACT scoring system for bone erosions of the finger joints in RA has demonstrated excellent reliability on static images. Further studies are required to evaluate the reliability of the combined acquisition and reading of images in patients. Image/graph:Figure 1. Representative images of the different grades of the scoring system for bone erosion in rheumatoid arthritis. A) grade 0: intact cortical bone; B) grade 1: single small erosion (diameter: ≤2mm); C1) grade 2: single large erosion (diameter: >2mm); C2) grade 2: 2 small erosions; C3) grade 2: 1 large and 1 small erosion; D1) grade 3: 2 large erosions; D2) grade 3: ≥3 erosions, regardless of size REFERENCES: NIL. Acknowledgements: NIL. Disclosure of Interests None Declared. Keywords: Rheumatoid arthritis, Cartilage, Ultrasound DOI: 10.1136/annrheumdis-2023-eular.2842Citation: , volume 82, supplement 1, year 2023, page 303Session: New developments in imaging in rheumatology (Poster Tours)