Background: For the development of both rheumatoid arthritis (RA) and psoriatic arthritis (PsA) concepts of (chronic) disease development from asymptomatic over arthralgia to arthritis have been proposed [1, 2] and first studies on disease prevention/interception have recently been published [3-5]. In early disease stages, it can be difficult to distinguish preclinical RA from PsA since there are sometimes no antibodies in preRA (rheumatoid factor and/or ACPA) and/or lack of other biomarkers (e.g., visible signs of PsO).

Objectives: To characterize and differentiate preclinical RA and PsA by clinical parameters and by the imaging methods musculoskeletal ultrasound (MSUS) and fluorescence optical imaging (FOI) in patients with arthralgia (without clinical arthritis) and clinically suspected RA or PsA and to determine their potential role in disease prediction.

Methods: Adult patients with inflammatory arthralgia suspicious for RA or PsA (with confirmed psoriasis) are continuously included in this project. These patients are reviewed for the development of clinical arthritis (in case of suspected RA) or clinical arthritis, dactylitis or enthesitis (in case of suspected PsA) over three years with scheduled visits at baseline, after 4, 12, 24, and 36 months. At each visit, the following examinations are performed: tender joint count (TJC-68), swollen joint count (SJC-66), DAS28-ESR, SDAI (Simple Disease Activity Index), CDAI (Clinical Disease Activity Index), patient’s and physician’s global disease activity (VAS 0-100 mm), patient’s assessment of pain (VAS 0-100mm), PASI/NAPS (only in suspected PsA), laboratory parameters, especially autoantibodies (rheumatoid factor (RF-IgM) and ACPA) as well as imaging parameters by musculoskeletal ultrasound (MSUS) in greyscale (GS) and power Doppler (PD) and fluorescence optical imaging (FOI). MSUS is done for the detection of synovitis and tenosynovitis (both wrists, MCP and (P)IP1-5, and MTP1-5) in GS and PD (each 0-3), and enthesitis (both common flexor and extensor tendons, quadriceps and patellar tendons, and Achilles tendons). FOI of both hands is performed by the Xiralite method in a standardized manner using PrimaVista Mode (PVM) and three predefined phases (p1-p3).

Results: Fifty-eight participants have been included, 32 (28 female with an average age of 46±12.3) assigned to the group of suspected RA and 26 (14 female with an average age of 47±10.2) to the group of suspected PsA. In the suspected RA group we had seven (22%) RF (IgA and/or IgM) and eight (25%) ACPA positive patients. In the suspected PsA group, we had one with ACPA positivity; all were RF negative. The average symptom duration was 21.2±19.2 months (suspected RA) vs. 27.2±27.7 months (suspected PsA) at inclusion. At baseline, suspected RA clinically presented with a mean TJC-68 of 5.9±8.1 vs. 10.2±11.2 for suspected PsA; all participants had an SJC-66 of 0.0±0.0 at inclusion. Their clinical disease activity scores were 2.6±1.2 vs. 2.8±1.3 (DAS28), 9.4±7.0 vs. 10.4±7.6 (SDAI), and 7.1±6.0 vs. 8.4±6.5 (CDAI) for suspected RA vs. PsA. Patient’s VAS (0-100mm) for global disease activity was 29.5±20.2 vs. 40.8±24.1 and for pain it was 26.4±20.7 vs. 39.8±27.4. Mean sum scores for synovitis and tenosynovitis by MSUS were as follows for suspected RA vs. PsA: GS-synovitis 10.9±6.1 vs. 10.6±5.6, PD-synovitis 1.5±2.4 vs. 0.7±1.5, GS-tenosynovitis 0.8±2.3 vs. 1.0±1.8, PD-tenosynovitis 0.6±1.9 vs. 0.1±0.3. Mean sum scores by FOI were as follows: PVM 5.8±7.6 vs. 6.3±7.4, p1 3.2±6.6 vs. 0.7±1.5, p2 9.2±9.2 vs. 8.3±8.4, and p3 0.2±0.5 vs. 0.2±0.4 for suspected RA vs. PsA. So far, nine out of 32 (28%) and three out of 23 patients (13%) have been diagnosed with RA and PsA over time. For the prediction of RA, SDAI (AUC 0.7) as well as GS/PD-synovitis, GS-tenosynovitis and FOI in PVM/p2 (each AUC 0.62) have a certain predictive power. For the prediction of PsA, patient’s and physician’s VAS for global disease activity (AUC 0.73/0.74), pain (AUC 0.68) as well as GS-tenosynovitis (AUC 0.77), PD- tenosynovitis (AUC 0.83) and FOI p3 (AUC 0.60).

Conclusion: Patients with preclinical RA have lower clinical disease activity scores, but higher scores on imaging (PD+/FOI-p1). For the prediction of both diseases, clinical and imaging (especially tenosynovitis by MSUS) seem to play a major role. Further investigation, also to better distinguish differences of preclinical RA/PsA and factors of their prediction are needed.

REFERENCES: [1] van Steenbergen HW, da Silva JAP, Huizinga TWJ, van der Helm-van Mil AHM. Preventing progression from arthralgia to arthritis: targeting the right patients. Nat Rev Rheumatol. 2018 Jan;14(1):32-41.

[2] Zabotti A, Tinazzi I, Aydin SZ, McGonagle D. From Psoriasis to Psoriatic Arthritis: Insights from Imaging on the transition to Psoriatic Arthritis and Implications for Arthritis Prevention. Curr Rheumatol Rep. 2020 May 16;22(6):24.

[3] Krijbolder DI, Verstappen M, van Dijk BT et al. Intervention with methotrexate in patients with arthralgia at risk of rheumatoid arthritis to reduce the development of persistent arthritis and its disease burden (TREAT EARLIER): a randomised, double-blind, placebo-controlled, proof-of-concept trial. Lancet. 2022 Jul 23;400(10348):283-294.

[4] Rech J, Schett G. Towards preventive treatment of rheumatoid arthritis. Lancet. 2022 Jul 23;400(10348):253-255. doi: 10.1016/S0140-6736(22)01327-7. PMID: 35871801.

[5] Zabotti A, Giovannini I, McGonagle D, De Vita S, Stinco G, Errichetti E. Arthritis Interception in Patients with Psoriasis Treated with Guselkumab. Dermatol Ther (Heidelb). 2022 Jan;12(1):5-8.

Acknowledgements: One of the authors (SO) was supported by the ‘Advanced Clinician Scientist Program (ACSP)’ of the German Society of Internal Medicine (DGIM).

Disclosure of Interests: Norman Nendel: None declared, Jens Klotsche: None declared, Gabriela Schmittat: None declared, Marina Backhaus: None declared, Gerhard Krönke: None declared, Gerd R. Burmester: None declared, Georgios Kokolakis: None declared, Sarah Ohrndorf I have been paid as a speaker for AbbVie, Alfasigma, Amgen, AstraZeneca, BMS, Johnson&Johnson, Lilly, Novartis, and UCB, Johnson&Johnson, Novartis and UCB, Novartis Pharma and GlaxoSmithKline Pharma.

© The Authors 2025. This abstract is an open access article published in Annals of Rheumatic Diseases under the CC BY-NC-ND license ( http://creativecommons.org/licenses/by-nc-nd/4.0/ ). Neither EULAR nor the publisher make any representation as to the accuracy of the content. The authors are solely responsible for the content in their abstract including accuracy of the facts, statements, results, conclusion, citing resources etc.