POS1041 EARLY DIAGNOSIS OF RHEUMATOID ARTHRITIS: ROLE OF JOINT ULTRASOUND ASSESSMENT
Authors: C. Corrales-Selaya, S. Fernández, I. Morante Bolado, M. Santos Gómez, V. Portilla González, S. Alonso-Castro, J. Rueda-Gotor, A. Corrales Martinez
Journal: Annals of the Rheumatic Diseases (2024)

<h3>Background:</h3> Early diagnosis of Rheumatoid Arthritis (RA) is essential to establish treatment to improve long-term disease outcomes. Musculoskeletal ultrasound (US) is able to detect subclinical synovitis and erosions earlier than simple radiological study. In recent years, several reduced joint US assessment models have been developed to allow global evaluation of synovitis and joint erosions. <h3>Objectives:</h3> To evaluate the diagnostic ability of a reduced joint US assessment model in patients with clinically suspected RA. <h3>Methods:</h3> Descriptive cross-sectional study of 203 consecutive patients sent to US care unit for study of suspected RA, but not fulfilling EULAR/ACR 2010 RA Classification Criteria. All patients were classified into 6 different groups: a) Seropositive (RF and/or ACPA positive) mono-oligoarthritis, b) Seropositive inflammatory arthralgias, c) Nonspecific seropositive arthralgias, d) seronegative arthralgias (RF and ACPA negative), e) Seronegative inflammatory arthralgias and f) Seronegative nonspecific arthralgias. They underwent a reduced standardized ultrasound count to evaluate synovitis of 20 joints (bilateral wrists, 1<sup>st</sup>-5<sup>th</sup> metacarpophalangeal (MCPs) and 2<sup>nd</sup>-5<sup>th</sup> metatarsophalangeal (MTPs) and a simplified ultrasound count of erosions of 10 joints (bilateral wrists, 2nd and 5th MCPs, 2nd hands proximal interphalangeal (PIP) and 5<sup>th</sup> MTP). B-mode synovial hypertrophy (SH) and synovial Power Doppler (PD) signal were scored from 0-3 at each joint of hands meanwhile only synovial PD signal were scored in metatarsophalangeal joints. Only scores ≥ 1 on both B-mode or power doppler were considered as synovitis. Definitive diagnosis was based on the number of inflamed joints detected by physical examination and new joints where synovitis was identified on ultrasonography. <h3>Results:</h3> We included 203 patients, 80% were women and mean age was 54 ± 13 years. The main demographic, clinical features and laboratory tests are shown in Table 1. Eighty-five patients (42%) were finally diagnosed with RA (Table 1). Subgroups with the highest percentage of RA diagnosis were the following in decreasing order of frequency seropositive arthritis (93.8%), seropositive inflammatory arthralgias (76.9%), seronegative arthritis (40.3%) and seropositive nonspecific arthralgias (29.4%). Only 15.2% and 5.6% of the patients had RA diagnosis in the seronegative inflammatory arthralgias and seronegative nonspecific arthralgias group, respectively. Undifferentiated arthritis was diagnosed in 57 patients (28.1%) as they did not meet the EULAR/ACR 2010 RA classification criteria. Most of patients in this group (55/57; 96%) come from seronegative patient groups, mainly seronegative arthritis (n=31) and seronegative inflammatory arthralgias (n=21). Other diagnoses included preferentially patients who had non-specific arthralgias and osteoarthritis. None of the patients had erosions in simple radiological study. However, they were found in 36 (18%) patients by US assessment. This is important as it may contribute to reaching an early diagnosis and it is a poor long-term functional prognostic factor. Finally, from the initial group of seropositive arthritis, which mainly included arthritis of 1 joint (large or small) or 2 joints (1 large and 1 small), a final diagnosis of RA was reached in 94%, remaining the diagnosis of undifferentiated arthritis in 1/16. In contrast, in the seronegative arthritis group, which included arthritis of 1-9 joints, RA diagnosis was only reached in 40%, remaining 46% (31/67) in the group of undifferentiated arthritis. This fact highlights the difficulty in reaching definitive diagnosis of RA in seronegative patients. <h3>Conclusion:</h3> Reduced US joint assessment are an effective method that helps to establish an early diagnosis and treatment of RA and can contribute to improve the prognosis. The degree of efficacy depends on the clinical situation prior to the US study. <h3>REFERENCES:</h3> <b>NIL.</b> <b>Table 1.</b> Demographic, clinical features, laboratory tests and final ultrasound diagnosis of 203 patients. <h3>Acknowledgements:</h3> <b>NIL.</b> <h3>Disclosure of Interests:</h3> <b>None declared.</b>