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Abstract
Background Psoriatic arthritis (PsA) and axial spondyloarthritis (axSpA) show certain overlaps: A subset of patients with PsA can develop axial involvement (axial PsA, axPsA), while a subset of patients with axSpA presents with psoriasis (axSpA+pso). Treatment strategy for axPsA is mostly based on axSpA evidence.
Objectives To compare demographic and disease-specific parameters of axPsA and axSpA+pso.
Methods RABBIT-SpA is a prospective longitudinal cohort study. AxPsA was defined based on (1) clinical judgement by rheumatologists; (2) imaging (sacroiliitis according to modified New York criteria in radiographs or signs of active inflammation in MRI or syndesmophytes/ankylosis in radiographs or signs of active inflammation in spine MRI). axSpA was stratified into axSpA+pso and axSpA without pso.
Results Psoriasis was documented in 181/1428 axSpA patients (13%). Of 1395 PsA patients, 359 (26%) showed axial involvement. 297 patients (21%) fulfilled the clinical definition and 196 (14%) the imaging definition of axial manifestation of PsA. AxSpA+pso differed from axPsA regardless whether clinical or imaging definition was used. axPsA patients were older, more often female and less often HLA-B27+. Peripheral manifestations were more often present in axPsA than in axSpA+pso, whereas uveitis and inflammatory bowel disease were more common in axSpA+pso. Burden of disease (patient global, pain, physician global) was similar among axPsA and axSpA+pso patients.
Conclusions AxPsA differs from axSpA+pso in its clinical manifestations, irrespective of whether axPsA is defined clinically or by imaging. These findings support the hypothesis that axSpA and PsA with axial involvement are distinct entities, so extrapolation of treatment data from randomised controlled trials in axSpA should be performed with caution.
- psoriatic arthritis
- spondylitis, ankylosing
- epidemiology
Data availability statement
Data are available on reasonable request. Applications to access the data should be made to the corresponding author.
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Data availability statement
Data are available on reasonable request. Applications to access the data should be made to the corresponding author.
Supplementary materials
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Footnotes
Twitter @AnneRegierer, @ProftDr
Contributors ACR had full responsibility for the finished work and the conduct of the study, had access to the data, and controlled the decision to publish. ACR and AW had full access to all of the data in the study and were involved in analysis and interpretation of the data. ACR and AW took responsibility for the integrity of the data and the accuracy of the data analysis. ACR, AW, FP, XB, FB, DP, GS and AS were involved in study initiation, conception and design. All authors were involved in drafting the article and revising it critically for important intellectual content, and approved the final version to be published.
Funding RABBIT-SpA is supported by a joint, unconditional grant from AbbVie, Amgen, Biogen, Celltrion, Hexal, Janssen-Cilag, Lilly, MSD, Novartis, Pfizer, UCB and Viatris.
Competing interests None declared.
Provenance and peer review Not commissioned; externally peer reviewed.
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