The Heterogeneity of Psoriatic Arthritis

The Top Research in PsA Presented at ACR Convergence 2023

Dr. David Pisetsky, the founding editor of The Rheumatologist, weighs in with his picks for the top research in psoriatic arthritis presented at ACR Convergence 2023.

SAN DIEGO—Psoriatic arthritis (PsA) is a complex clinical condition that can present with variable joint findings and variable skin findings (e.g., psoriasis). PsA was once classified as a rheumatoid variant but, nevertheless, differs from rheumatoid arthritis (RA) in genetics, involvement of the entheses and the presence of axial disease. Differences also include the response to biological agents, as indicated by regulatory approvals. Whereas tumor necrosis factor (TNF) inhibitors and abatacept have been approved for both RA and PsA, anti-interleukin (IL) 17, anti-IL-12/23 and anti-IL-23 antibodies have been approved for PsA and psoriasis.

These differences highlight the need for the development of imaging modalities, laboratory tests and other biomarkers that are explored and validated specifically for PsA and, therefore, can advance the goal of personalized or precision medicine. This is a large challenge because PsA itself is so heterogeneous.

The abstracts for ACR Convergence 2023 illustrate the challenge well. Although advanced imaging (e.g., ultrasound, magnetic resonance imaging [MRI]) can reveal joint involvement in great detail, the interpretation of findings is complicated because of the uncertain relationship of clinical findings (e.g., pain) to the structures affected (e.g., synovium, entheses, bone). Big data approaches (e.g., transcriptomics, mass spectometry) carry enormous promise, but the mass of data that these analytic tools can generate will require new informatics platforms, including machine learning and artificial intelligence (AI) to make sense of the data and provide actionable information.

1. The Burden of Oligoarticular PsA

Abstract 0966: Olopoenia et al.¹

The clinical findings of PsA are highly heterogenous, contributing to challenges in diagnosis and treatment. The extent of skin disease varies widely, and patients display distinct patterns of involvement of joints and entheses to allow designation of disease subtypes. These subtypes include polyarthritis (poly), oligoarthritis (oligo), classic arthritis (with distal joint and nail involvement), arthritis mutilans and spondyloarthritis.

The polyarticular form of PsA tends to receive the most attention because, in clinical trials, the number of inflamed joints determines patient eligibility; enrollment, therefore, favors patients with polyarticular disease. Further, metrics similar to those used to evaluate RA, the prototypic form of polyarticular inflammatory arthritis, can be readily adapted to the study of polyarticular PsA.