Identification and characteristics of patients with potential difficult-to-treat psoriatic arthritis: exploratory analyses of the Greek PsA registry

Objective: To present the characteristics of patients with potential difficult-to-treat (D2T) PsA. Methods: We used data from the Greek multicentre registry of PsA patients. D2T PsA was defined as follows: patients with at least 6 months' disease duration, who have failed to at least one conventional synthetic DMARD and at least two biologic DMARDs/targeted synthetic DMARDs with a different mechanism of action and have either at least moderate disease activity (MODA) defined as DAPSA (Disease Activity index in PSoriatic Arthritis) >14, and/or are not at minimal disease activity (MDA). Demographic and clinical characteristics were compared between D2T and non-D2T PsA patients. In two sensitivity analyses, patients classified as D2T solely according to the MODA or MDA criterion were examined separately. Results: Among 467 patients included, 77 (16.5%) were considered D2T and 390 non-D2T PsA. Compared with non-D2T, patients with D2T PsA presented more commonly with extensive psoriasis (P < 0.0001) and were more likely to have higher BMI (P = 0.023) and a history of IBD (P = 0.026). In the MODA and MDA sensitivity analyses, 7.5% and 12.5% of patients were considered D2T, respectively. In both sensitivity analyses, extensive psoriasis was again identified as an independent variable for D2T PsA (P = 0.001 and P = 0.008, respectively). Moreover, female gender (P = 0.034) in the MODA analysis and axial disease (P = 0.040) in the MDA analysis were independent variables for D2T PsA. Conclusion: Despite the availability of therapies, D2T PsA is common in real-life cohorts of patients with PsA and extensive psoriasis. High BMI, female gender, axial disease and history of IBD were also associated with D2T PsA.