Study Identifies Differences in Outpatients With AS and Axial PsA

Compared with patients with axial psoriatic arthritis (PsA), patients with ankylosing spondylitis (AS) are younger, more often male, and have lower body mass index (BMI), according to a real-world comparison of outpatients at rheumatology clinics from two hospitals. Researchers published their findings online ahead of print in Clinical and Experimental Rheumatology.

“Axial involvement affects 25% to 70% of PsA patients, depending on the criteria used for its definition,” wrote researchers from Athens, Greece. “Efforts are underway to clarify the similarities and differences between axial PsA and AS.”

The study included 128 patients diagnosed with AS per New York criteria and 78 patients diagnosed with PsA per Classification Criteria for Psoriatic Arthritis (CASPAR) with axial involvement. Participants were regular outpatients in the rheumatology clinics.

In addition to being younger, more frequently male, and having a lower BMI compared with patients with axial PsA, patients with AS were diagnosed at a younger age and more frequently HLA-B27-positive, according to the study.

When researchers looked at comorbidities, they found peripheral arthritis, dactylitis, and nail involvement were less common in patients with AS, as opposed to eye and bowel involvement. The groups had similar frequency of radiologic abnormalities in the spine. Sacroiliitis, however, tended to be bilateral in patients with AS and unilateral in those with axial PsA.

“Comorbidities, including cardiovascular-related ones, were comparable between AS and axial PsA, apart from depression,” researchers wrote, “which was more frequent in axial PsA."

Reference:
Fragoulis GE, Pappa M, Evangelatos G, Iliopoulos A, Sfikakis PP, Tektonidou MG. Axial psoriatic arthritis and ankylosing spondylitis: same or different? A real-world study with emphasis on comorbidities [published online ahead of print, 2021 Jul 24]. Clin Exp Rheumatol. 2021.