Pos1521 characteristics of difficult to treat psoriatic arthritis: a comparative analysis

Background The concept of difficult-to-treat rheumatoid arthritis (D2T RA) has recently emerged. It is defined by the persistence of disease activity and the failure of at least 2 b/tsDMARDs of 2 different mechanisms of action (MoA) [1]. In this definition, the period of time during which the treatments have failed is not included. The D2T concept has not yet been applied with consensus in psoriatic arthritis (PsA). Objectives To study the characteristics of patients with D2T PsA to better identify the potential causes of treatment failure. The 2 nd objective was to study a sub-group of D2T PsA patients with a predefined time criteria. Methods A monocentric retrospective longitudinal study was performed in a tertiary center. PsA diagnosis was based on CASPAR criteria. Patients were followed up from February 2004 to August 2022. Patients starting a b/tsDMARDs with a minimum of 2-year follow-up were included. D2T PsA patients were defined as patients who received more than 2 b/tsDMARDs with different MoA among b/tsDMARD available. These patients were compared to non-D2T PsA patients (nD2T PsA) using statistical tests. Very D2T PsA patients were defined as patients who received at least 2 b/tsDMARDs in less than 2 years during the time of follow-up. Results 150 patients were included, 49 were D2T PsA and 101 nD2T PsA. Baseline characteristics are presented in the Table 1. No statistical difference was found between the 2 groups regarding main comorbidities, including fibromyalgia and depression. In the D2T PsA group, 91.7% and 69.1% of patients received an anti-TNF alpha as the 1 st and 2 nd lines of treatment; anti-IL17 drugs represented 0% and 12.2% of 1 st and 2 nd lines; anti-IL12-23 represented 8% and 18.4% of prescriptions in 1 st and 2 nd lines. After 3 lines, 38.8% of patients had received 3 bDMARDs with different MoA, 30.6 % received 2 bDMARDs with different MoA. 17 patients were categorized as very D2T PsA. When compared to the rest of the D2T PsA group, no significant difference was observed. Proportion of men was 64.7% (p=0.39). Mean age was 55.0 ± 8.3 yo (p=0.67) and mean BMI was 30.4 ± 6.5 kg/m 2 (p=0.65). Table 1. Baseline characteristics of patients Parameters N D2T PsA n = 49 N nD2T PsA n = 101 p value Men 49 29 (59.2) 101 52 (51.5) 0.37 Age (years), mean ± SD 49 54.2 ± 11.9 101 53.7 ± 14.2 0.82 BMI, mean ± SD 46 29.6 ± 7.2 96 27.7 ± 5.7 0.093 PsA duration (years), median (IQR) 49 17.0 (8.0 to 20.0) 99 11.0 (6.0 to 21.0) 0.22 Current smoker status 49 16 (32.7) 101 33 (32.7) 1.00 Clinical PsA characteristics at baseline Axial involvement 48 21 (43.8) 100 26 (26.0) 0.030 Peripheral involvement 49 49 (100) 101 99 (98) NA Monoarthritic 48 3 (6.3) 101 11 (10.9) - Oligoarthritic 48 22 (45.8) 101 51 (50.5) - Polyarthritic 48 23 (47.9) 101 37 (36.6) - Dactylitis 45 10 (22.2) 101 32 (31.7) 0.24 Psoriasis at baseline 49 6 (12.2) 101 12 (11.9) 0.95 Structural damage at baseline (axial and peripheral) 42 32 (76.2) 96 49 (51.0) 0.006 IBD 49 0 (0.0) 101 3 (3.0) NA Baseline CRP (mg/L), median (IQR) 40 13.6 (6.0 to 31.5) 86 8.1 (3.0 to 20.0) 0.11 BASDAI Baseline, mean ± SD 8 65.1 ± 16.6 22 58.5 ± 11.7 0.23 bDMARD discontinuation due to poor dermatological control 47 19 (40.4) 101 19 (18.8) 0.005 Values are expressed as number (%) unless otherwise stated. BASDAI: Bath Ankylosing Spondylitis Disease Activity Index; bDMARD: biological disease modifying antirheumatic drug; BMI: body mass index; CRP: C-reactive protein; (n)D2T: (non) difficult-to-treat; HLA: human leukocyte antigen IBD: inflammatory bowel disease; IQR: interquartile range; N: number of available observations; NA: not applicable; PsA: psoriatic arthritis; SD: standard deviation. Conclusion Significant differences were found between the characteristics of patients D2T PsA and nD2T PsA, which were the presence of axial manifestation, structural damage at baseline and discontinuation due to poor dermatological control. Limitations exist about applying the EULAR D2T RA definition to PsA. The inclusion of a time period should also be considered. Reference [1]Nagy G, Roodenrijs NM, Welsing PM, et al. EULAR definition of difficult-to-treat rheumatoid arthritis. Ann Rheum Dis 2021;80:31–5. Acknowledgements: NIL. Disclosure of Interests None Declared.