Frequency and characteristics of axial involvement in psoriatic arthritis: results from the international multicentre AXIS study

Journal article

Objective: The Axial Involvement in Psoriatic Arthritis (AXIS) cohort aimed at evaluating the frequency of, and clinical and imaging features of axial involvement in psoriatic arthritis (PsA).

Methods: AXIS (NCT04434885) is a prospective, multicenter, cross-sectional study conducted in 19 countries, by ASAS and GRAPPA. Participants with a diagnosis of PsA meeting CASPAR with musculoskeletal symptom duration ≤10 years and no prior exposure to biological or targeted synthetic DMARDs were consecutively included. Standardized clinical, laboratory, and imaging assessments (radiography and MRI of axial skeleton including sacroiliac joints-SIJ and spine) were performed. Imaging was reviewed locally and centrally to detect axial involvement. The presence of axial involvement was determined by local investigator judgment before and after central imaging review.

Results: Among 409 participants, axial involvement was identified in 153 (37.4%) based on investigator’s initial assessment, was decreased to 112 (27.4%) in final evaluation after incorporating central imaging review. Participants with axial involvement were younger (45.2±13.8 vs. 47.6±12.6 years), more often male (56.3% vs. 51.5%), and had higher frequency of HLA-B*27 positivity (22.4% vs. 10.8%), inflammatory back pain (IBP) (74.7% vs. 43.4%), and elevated CRP (52.7% vs. 37.4%). Active inflammatory and structural imaging changes were highly discriminative between participants with and without axial involvement. The central review identified imaging signs of axial involvement (active inflammation or structural lesions) in 95 participants (23.2%).

Conclusion: Axial involvement was identified in 27.4% of participants with PsA after final diagnostic assessment, with associated features including HLA-B*27 positivity, IBP, elevated CRP, and imaging changes in SIJ or spine.

Authors: Torgutalp, M; Almodovar, R; Azevedo, VF; Coates, L; Poddubnyy, D

• Publication status: Accepted
• Peer review status: Peer reviewed
• Publisher: Elsevier
• Journal: Annals of the Rheumatic Diseases
• Publication date: 2026-03-26
• Acceptance date: 2026-02-28
• DOI: 10.1016/j.ard.2026.02.025
• EISSN: 1468-2060
• ISSN: 0003-4967
• Language: English
• Keywords: axial involvement; Axial PsA; spondyloarthritis; AxPsA; AxSpA; FFR