AB0979 PREDICTIVE FACTORS FOR FAILURE OF FIRST-LINE CsDMARDs MONOTHERAPY IN PSORIATIC ARTHRITIS

Background: As recommended by the international guidelines, conventional synthetic disease-modifying antirheumatic drugs (CsDMARDs) are the first-line treatment for psoriatic arthritis (PsA) [1]. Objectives: This study aims to identify predictive factors for the failure of first-line CsDMARD prescribed as monotherapy in patients with PsA. Methods: Retrospective cohort study including 71 patients with PsA meeting the criteria of the Assessment of SpondyloArthritis International Society (ASAS) and/or Classification Criteria for Psoriatic Arthritis (CASPAR). Sociodemographic data, disease characteristics, and treatment history were collected. Results: Our study included 71 patients (22 females and 49 males) with a mean age of 50.8 ± 14.2 years [24-80]. The average diagnostic delay was 5.9 ± 5.1 years [0-30]. Axial involvement was observed in 31 patients (37.3%), with 31.3% experiencing cervical pain, 19.3% dorsal pain, 37.3% lumbar pain, and 22.9% buttock pain (9 unilateral, 6 bilateral, and 4 alternating). Peripheral joint involvement affected 42.2% of patients (n=35). Enthesitis was present in 37.3% (n=31) of patients and dactylitis was reported in 25.3% (n=21). Cutaneous psoriasis was present in 63.9% of cases, nail involvement in 31.3%, and scalp involvement in 38.6%. Structurally, sacroiliitis was noted in 41%, cervical spine involvement in 24.1%, dorsal spine involvement in 25.3%, lumbar spine involvement in 19.3%, and coxitis in 78.3%. Methotrexate (MTX) was prescribed as first-line treatment in 81.5% patients (n= 58) with an average weekly dose of 13.8 ± 4 mg [7.5-20]. Among these patients, 16 (27.5%) experienced therapeutic failure and were switched to Leflunomide (n=2), Sulfasalazine (n=14), and anti-Tumor Necrosis Factor (n=10). MTX failure was associated with scalp psoriasis (OR=0.191, 95% CI [0.057-0.646], p=0.006), buttock pain (OR=0.692, 95% CI [0.482-0.995], p=0.025), radiographic sacroiliitis (OR=2.989, 95% CI [1.001-9.390], p=0.05), and coxitis (OR=4.333, 95% CI [1.001-18.767], p=0.05). Moreover, diagnostic delay was significantly shorter in patients with MTX failure (3.9 versus 7.86 years, p=0.016), while the number of swollen joints was higher (5.25 versus 1.39, p=0.002). Conclusion: Our study revealed that scalp psoriasis and buttock pain are predictive factors for a good response to methotrexate in patients with PsA naïve to treatment. On the other hand, structural progression (attested by sacroiliitis and coxitis), short diagnostic delay and arthritis are factors associated with treatment failure. These findings may guide therapeutic reinforcement decisions to ensure a rapid and effective management of Psoriatic Arthritis. REFERENCES: [1] Jacobs ME, Pouw JN, Welsing P, Radstake TRDJ, Leijten EFA. First-line csDMARD monotherapy drug retention in psoriatic arthritis: methotrexate outperforms sulfasalazine. Rheumatology (Oxford). 2021 Feb 1;60(2):780-784. Acknowledgements: NIL. Disclosure of Interests: None declared.