What Are the Risk Factors?

TOPLINE:

Approximately one quarter of patients with psoriatic arthritis (PsA) exhibited axial involvement (axial PsA). Enthesitis, inflammatory bowel disease, and HLA-B27 positivity were associated with an increased risk for axial PsA.

METHODOLOGY:

• Researchers utilised data from a large multicentre study in Greece to analyse the clinical phenotype of patients with axial PsA.
• Data were collected cross-sectionally from rheumatology centres and private practices between January and December 2022.
• Axial PsA was defined using the ClASsification for Psoriatic ARthritis criteria as PsA with inflammatory back pain and positive imaging findings on MRI or x-rays.
• Patients were categorised into subgroups on the basis of sacroiliac joint or spinal involvement. Comparisons were also made between those with non-radiographic findings (lesions noted only on MRI in the sacroiliac joint and/or rest of the spine, but not on x-rays of the same regions) and those with radiographic findings (structural damage observed on x-rays).
• Overall, 922 patients with PsA were included. According to the proposed definition, 238 were considered to have axial PsA (mean age, 55.5 years; 51% women) and 684 were considered to have non-axial PsA (mean age, 56.2 years; 58% women).

TAKEAWAY:

• Among patients with axial PsA, 42.4% showed isolated sacroiliac joint involvement, 31.5% showed isolated spinal involvement, and 26.1% had both.
• Patients with peripheral arthritis at diagnosis had a decreased risk of developing axial PsA (odds ratio [OR], 0.47; 95% CI, 0.33-0.66), whereas the presence of enthesitis (OR, 1.65; 95% CI, 1.11-2.45) or inflammatory bowel disease (OR, 2.58; 95% CI, 1.05-6.33) was associated with an increased risk.
• HLA-B27 positivity was associated with an increased risk for axial PsA (OR, 7.87; 95% CI, 3.11-19.95).
• The presence of enthesitis at diagnosis (OR, 3.37; 95% CI, 1.66-6.82) and younger age (OR, 0.97; 95% CI, 0.94-0.99) were independently associated with isolated sacroiliac axial PsA.
• Non-radiographic axial PsA was identified in 35% of patients. Younger age (OR, 0.96; 95% CI, 0.94-0.99) and female sex (OR, 2.59; 95% CI, 1.39-4.82) were independently associated with non-radiographic axial PsA.

IN PRACTICE:

“These initial observations may aid rheumatologists in formulating the suitable evaluation of patients with PsA and/or psoriasis and inflammatory back pain, as well as in determining therapeutic interventions,” the authors wrote.

SOURCE:

The study was led by Konstantinos D. Vassilakis, National and Kapodistrian University of Athens, School of Medicine, Athens, Greece. It was published online on March 8, 2025, in Rheumatology.

LIMITATIONS:

The retrospective collection of radiologic findings may have introduced bias, as non-expert radiologists might misinterpret MRI and x-ray results. Data were not collected prospectively, leading to variability in imaging modalities among participants. Missing data on HLA-B27 status limited its inclusion in the multivariate model.

DISCLOSURES:

The registry used for the study was supported by the Greek (Hellenic) Rheumatology Society. The authors reported no relevant conflicts of interest.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.