POS1047 CLINICAL AND ULTRASOUND FEATURES IN AN INCEPTION COHORT OF TREATMENT NAÏVE PATIENTS WITH PSORIATIC ARTHRITIS

Background: Assessing a newly diagnosed patient with psoriatic arthritis (PsA) can be challenging, and the correct evaluation of clinical features may influence treatment decisions and prognosis. Current treatment recommendations underline this, as patients are stratified based on features such as enthesitis, predominant axial disease, or predominant skin and nail disease [1]. Ultrasound can be an important clinical tool to ensure correct treatment decisions from the onset of the disease. Objectives: To describe the clinical and ultrasound characteristics of treatment naïve PsA patients starting their first disease-modifying anti-rheumatic drug, including structured assessment of disease activity in joints, entheses, skin, and nails. Methods: Patients diagnosed with PsA who fulfilled the ClASsification for Psoriatic Arthritis (CASPAR) criteria starting their first disease-modifying antirheumatic drug were included in an ongoing Norwegian multi-center study (NCT05291819). Patients underwent extensive clinical and ultrasound assessments. The clinical examination of joints included assessments of 66/68 swollen (SJC) and tender (TJC) joints and identification of dactylitis. The presence of enthesitis was evaluated clinically according to the Leeds Enthesitis Index (LEI) and the Spondyloarthritis Research Consortium of Canada (SPARCC) enthesitis scoring system. Skin- and nail involvement was assessed by psoriasis body surface area (BSA), static Physician Global Assessment of Psoriasis (sPGA), and modified Nail Psoriasis Severity Index (mNAPSI). The Disease Activity Index for Psoriatic Arthritis (DAPSA) was used to assess the disease activity, and patient-reported outcomes were collected, such as patient global assessment of disease, pain, and Bath Ankylosing Spondylitis Disease Activity Index (BASDAI). All patients underwent a comprehensive ultrasound protocol with evaluation of 74 joints, 20 tendons of the hands, and 14 entheses, all scored according to OMERACT definitions. Ultrasound inflammation was defined by power Doppler (PD) >0 in any joint, enthesis, flexor tendon sheath of the fingers, or within a peritenonitis proximal to the MCP joints. The grayscale (GS) sum score is comprised of joints, the flexor tendons of the hands, peritenonitis, and the inflammatory enthesis findings of hypoechogenicity and increased thickness. Results: A total of 111 consecutive patients were included in this analysis; 64% were male, and the mean (SD) age was 44.2 (14.0) years. 93% of the patients had a history of psoriasis, while in the remaining 7% it was present in a first-degree family member (Table 1). Physician-reported history of arthritis was the most prevalent disease feature, identified in 86% of patients. A history of axial involvement was documented in 29%, enthesitis in 30%, and nail psoriasis in 47% of patients. At the time of assessment, the median (IQR) SJC was 2 (1-4) and TJC 4 (2-8). Patient global assessment of disease activity visual analog scale (VAS) was 59 (41-70), VAS pain was 60 (40-70), and CRP 5 mg/L (2-11 mg/L), whereas the VAS physician global assessment of disease was 25 (15-40). 80% had a SJC>0. The baseline DAPSA had a median (IQR) value of 18.4 (12.5-28.3), corresponding to moderate disease activity. The skin disease among the patients was mild. Although 87% had any psoriasis plaque, the median (IQR) BSA was 2% (1-4%), sPGA score 3 (2-4), and mNAPSI score 1 (0-8). The median ultrasound GS sum score was 11 (5-22) (Table 2). When focusing solely on the GS score for joints, a GS >1 was observed in 75% of patients. The median PD sum score was 3 (0-7), with 69% having a value >0 in any of the ultrasound-examined structures. 52% had any joint with PD>0. A PD-signal >0 was observed in an enthesis in 35% of the patients, with the lateral epicondyle being the most commonly affected enthesis (12%), followed by the proximal patellar tendon insertion (11%). Additionally, peritenonitis was identified in 19%, and flexor tenosynovitis in 21%. Conclusion: In this treatment naïve early PsA inception cohort with an aim to include all PsA patients starting DMARD treatment, extensive examinations illustrated the heterogeneous nature of the disease. After skin psoriasis, arthritis was the feature affecting most patients, with clinically swollen joints in 80% and ultrasound PD joint synovitis in 52%. Other aspects of PsA, such as a clinical finding of dactylitis and ultrasound findings of enthesitis, tenosynovitis, and peritenonitis, each had an overall prevalence of at least 20%, reflecting the diversity of this patient population. Ultrasound might add useful information about inflammation in a number of structures. In conclusion, extensive examination of affected structures is necessary to guide treatment decisions in early PsA. REFERENCES: [1] Gossec L, Kerschbaumer A, Ferreira RJO, et al. EULAR recommendations for the management of psoriatic arthritis with pharmacological therapies: 2023 update. Ann Rheum Dis. 2024; 83:706-19. Acknowledgements: NIL . Disclosure of Interests: Even Lillejordet: None declared, Nina Sundlisæter: None declared, Joseph Sexton: None declared, Camilla Fongen: None declared, Ellen Moholt: None declared, Maud-Kristine A Ljosa Advisory board: Abbvie, Cathrine Austad: None declared, Annicken Slagsvold: None declared, Bjørg Tilde Svanes Fevang: None declared, Hu Yi Speaker fee: Boehringer Ingelheim, Gunnstein Bakland Speaker fee: Johnson&Johnson, Agnete Gulati: None declared, Inger M. Hansen: None declared, Martyna Dobel-Rynning: None declared, Mathias Møgster Braaten: None declared, Anja Myhre Hjelle: None declared, Désirée van der Heijde Consulting fees: AbbVie, Alfasigma, ArgenX, BMS, Lilly, Grey-Wolf Therapeutics, Janssen, Novartis, Pfizer, Takeda, UCB Pharma, Hilde Berner Hammer Speaker fees: AbbVie, UCB, Novartis, Lilly, Espen Haavardsholm Advisory board: Pfizer, AbbVie, Eli Lilly, Novartis, Siri Lillegraven: None declared. © 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.

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