POS0875 DEFINING THE THRESHOLD OF NORMALITY IN MUSCULOSKELETAL ULTRASOUND; AN OMERACT ULTRASOUND STUDY
Authors: I. Sahbudin, J. Trickey, H. Gouze, M. S. Stoenoiu, G. Filippou, G. Sakellariou, M. Maruseac, R. Wittoek, P. Carron, I. Tinazzi, A. Iagnocco, T. Serban, I. Azzolin, L. Terslev, M. Ammitzbøll-Danielsen, M. Nyhuus Bendix Rasch, E. M. Hauge, H. B. Hammer, M. Milchert, J. Fliciński, P. Mandl, C. Borst, D. Fodor, F. A. Vreju, R. Karalilova, E. Naredo, C. Sifuentes-Cantú, G. M. C. La Paglia, C. Pineda, M. Gutierrez, G. Leon, C. Reátegui-Sokolova, M. A. Mortada, T. Suzuki, K. Ikeda, C. Ciurtin, M. Kortekaas, S. Ohrndorf, H. Keen, G. Bruyn, A. Filer, M. A. D’agostino
Journal: Annals of the Rheumatic Diseases (2024)

<h3>Background:</h3> Improvement in ultrasound technology in the last decade results in high resolution images. Therefore, previously undetected ultrasound lesions in joints of asymptomatic healthy individuals have now become apparent. At present, the cut-off between normal vs abnormal sonographic findings in small joints is unclear. Therefore, the threshold of normality in ultrasound that discriminates normal physiological vs minimal pathological changes at each joint level in different age groups needs to be defined. <h3>Objectives:</h3> The objective of this study was to define the threshold of normality in ultrasound according to joint type and age groups. In order to achieve this, we systematically graded ultrasound lesions (synovial hypertrophy, Doppler activity and synovial effusion) in the metacarpophalangeal (MCP), proximal interphalangeal (PIP), wrist and metatarsophalangeal (MTP) joints of healthy individuals aged 18 – 80 years old. <h3>Methods:</h3> This was an observational cross-sectional multi-centre study under the 'Minimal Disease' subgroup of the OMERACT Ultrasound Working Group. Healthy individuals aged 18- 80 years old were included. Exclusion criteria were current/previous history of inflammatory arthritis, joint trauma of hands/wrist in previous month; hand/wrist pain with VAS ≥10/100; hand osteoarthritis according to American College of Rheumatology criteria; history of infection in the last month; and recent/current use of medications that could affect ultrasound assessment. Clinical data including age, sex, body mass index and ethnicity were recorded. Bilateral MCP, PIP, wrist and MTP joints were clinically examined by an independent assessor in each centre, and subjects were excluded if synovitis or swelling was detected. Ultrasound assessment of bilateral MCP 1- 5, PIP 1 – 5, wrist radio-carpal, inter-carpal and ulnar-carpal and MTP 1 – 5 was conducted according to EULAR standardised procedures. Presence of synovial hypertrophy, synovial effusion and Doppler activity of each joint were recorded using the EULAR-OMERACT semi-quantitative grading system; grade 0-3. All images were acquired, recorded and graded by the same sonographer during the scanning assessment and sent to the central hub. Quality and grading of recorded images were confirmed by a review of all images for the first participant recruited in each centre by an experienced blinded independent assessor (IS) in the hub centre. Any disagreement was then fed back to the centre and consensus was achieved to ensure reliability in subsequent scans. <h3>Results:</h3> 849 participants were recruited between Feb 2017 and July 2019 from 21 centres across 13 countries. 802 participants were included in final analysis (Figure 1). Median age was 42 years (IQR 30-56), and majority were female (72%) and white (81%). Other ethnic groups were Asian Japanese, Middle Eastern, Black, other Asian and mixed ethnicity. 28,735 joints were scanned; of these 3728 (13%) had at least one abnormal ultrasound finding. Highest proportion of ultrasound abnormal findings was observed in MTP 1 (45%) followed by MTP 2 (39%). Lowest proportion of changes was observed in wrist ulnar-carpal and MTP 5 (2%). Next, we identified the threshold of abnormality for each joint type by age groups. The threshold of abnormality chosen was 5% in line with conventional biomedical cut-off levels. (i.e. 95% of the normal population would fall within this threshold). Presence of Doppler activity in MCP, PIP, wrist and MTP joints should be regarded as abnormal in any age range. Presence of synovial hypertrophy in PIP 1 – 5 should be regarded as abnormal in any age range. Presence of synovial hypertrophy in MCP 5 and MTP 5 at any age is abnormal (Table 1). <h3>Conclusion:</h3> This is the first study that describes ultrasound changes observed in the MCP, PIP, wrist and MTP joints of normal population across a wide age range and nationalities. This gives an indication on what could constitute background changes or 'minimal disease changes' and what should be regarded as normal. This has major implication in the interpretation of ultrasound findings in rheumatology. <h3>REFERENCES:</h3> <b>NIL.</b> <h3>Acknowledgements:</h3> <b>NIL.</b> <h3>Disclosure of Interests:</h3> Ilfita Sahbudin: None declared, Jeanette Trickey: None declared, Hélène GOUZE: None declared, Maria Simona Stoenoiu: None declared, Georgios Filippou: None declared, Garifallia Sakellariou: None declared, Mihaela Maruseac: None declared, Ruth Wittoek: None declared, Phillippe Carron: None declared, Ilaria Tinazzi: None declared, Annamaria Iagnocco: None declared, Teodora Serban: None declared, Irene Azzolin: None declared, Lene Terslev Speakers fee from Janssen, Novartis and GE., Mads Ammitzbøll-Danielsen: None declared, Mads Nyhuus Bendix Rasch: None declared, Ellen-Margrethe Hauge: None declared, Hilde Berner Hammer Honoraria for lectures from AbbVie, Novartis, Lilly and UCB., Marcin Milchert: None declared, Jacek Fliciński: None declared, Peter Mandl: None declared, Carina Borst: None declared, Daniela Fodor: None declared, Florentin Ananu Vreju: None declared, Rositsa Karalilova: None declared, Esperanza Naredo: None declared, Cesar Sifuentes-Cantú: None declared, Giuliana M.C. La Paglia: None declared, Carlos Pineda: None declared, Marwin Gutierrez: None declared, Gustavo Leon: None declared, Cristina Reátegui-Sokolova: None declared, Mohammed A Mortada: None declared, Takeshi Suzuki: None declared, Kei Ikeda: None declared, Coziana Ciurtin: None declared, Marion Kortekaas: None declared, Sarah Ohrndorf Speakers' honoraria or travel expense reimbursements by: AbbVie, Amgen, BMS, Galapagos, Janssen, Mylan, Novartis, UCB, Helen Keen: None declared, George Bruyn: None declared, Andrew Filer: None declared, Maria Antonietta D'Agostino: None declared