Difficult-to-treat and complex-to-manage PsA: GRAPPA definitions and overarching principles

Many patients with psoriatic arthritis (PsA) experience treatment inefficacies and persistent disease burden despite guideline-based therapies, and definitions are lacking for difficult-to-treat PsA and complex-to-manage PsA. 

During the European Alliance of Associations for Rheumatology (EULAR) 2025 Congress, June 11–14, 2025, Barcelona, ES, Fabian Proft presented consensus definitions developed by the Group for Research and Assessment of Psoriasis and Psoriatic Arthritis (GRAPPA) along with overarching principles to provide a standardized framework to guide clinical decision-making and clinical trial inclusion/exclusion criteria. 

A scoping literature review was conducted, with global surveys completed by GRAPPA healthcare professionals (n = 223) and patients with PsA (n = 570). A multidisciplinary working group consisting of rheumatologists, dermatologists, patient research partners, and young-GRAPPA representatives from diverse regions, formulated the initial definitions. These were refined using a Delphi approach and endorsed by GRAPPA members using online voting.

Key learnings

GRAPPA defined complex-to-manage PsA as a disease state characterized by persistent symptoms despite at least one adequate trial of a ts- or b-DMARD recommended for PsA treatment (89% consensus).

Difficult-to-treat PsA (also known as treatment-refractory PsA) was defined as failure to respond to ≥3 previous PsA treatments with different modes of action (including ≥2 ts- or b-DMARDs), presence of persistent symptoms, and objective evidence of ongoing inflammation (100% consensus).

Overarching principles included the need for multidisciplinary care, shared decision-making, and diagnosis re-evaluation at inadequate treatment response (each 100% consensus). The overall findings were endorsed by 95.1% (175/184) of GRAPPA healthcare professional responders. 

These definitions and overarching principles provide a framework for clinical decision-making and may improve patient stratification and clinical trial criteria standardization, with the potential to improve outcomes in patients with complex and refractory disease.