Patients with axial psoriatic arthritis (axPsA) in Japan appear to have lower disease activity and better functional outcomes compared with patients in other regions, particularly elsewhere in Asia, according to new data from the international ASAS-PerSpA study.
The analysis highlights notable geographic differences in both disease phenotype and treatment strategies, underscoring the need for region-specific approaches to axPsA management.
Axial Involvement Common in Psoriatic Arthritis
The ASAS-PerSpA study included 4,465 patients with spondyloarthritis across multiple global regions. Among the 1,033 patients diagnosed with psoriatic arthritis by their rheumatologist, 367 (35.5%) were identified as having axial involvement.
Disease activity and functional impairment varied across regions. Overall, Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) scores ranged from 4.1 to 5.4, Ankylosing Spondylitis Disease Activity Score (ASDAS) from 2.5 to 3.2, and Bath Ankylosing Spondylitis Functional Index (BASFI) from 3.0 to 4.7.
Japanese Patients Show Milder Disease Profile
Patients from Japan demonstrated consistently lower disease activity and better function compared with other regions. Mean BASDAI was 3.5, ASDAS 2.2, and BASFI 1.6, indicating milder axial symptoms and less functional limitation.
When compared specifically with other Asian countries, Japanese patients still showed significantly lower BASDAI and BASFI scores, suggesting regional differences even within Asia. These findings may reflect differences in disease recognition, referral patterns, genetics, or healthcare systems.
Treatment Patterns Differ Across Regions
Treatment approaches also varied substantially by geography. Conventional synthetic disease-modifying antirheumatic drugs (csDMARDs) were used significantly less often in Japan than in other Asian countries, with utilization rates of 51.4% versus 78.1%, respectively.
Use of biologic DMARDs also varied across regions, reflecting differences in clinical practice, treatment guidelines, and access to therapies. The lower csDMARD use in Japan alongside lower disease activity raises questions about whether treatment intensity, disease phenotype, or early intervention strategies may influence outcomes.
Implications for axPsA Management
The findings suggest that axPsA presents differently across geographic regions and that management strategies are not uniform worldwide. Understanding these variations may help refine diagnostic criteria, guide treatment decisions, and inform future international guidelines.
The authors note that further research is needed to clarify whether observed differences are driven by biological factors, healthcare system structures, or treatment philosophies.
Reference
Sawada H et al. Disease phenotype and management of axial psoriatic arthritis in Japan compared with other regions, particularly other Asian countries: results of the ASAS-PerSpA study. BMC Rheumatol. 2025;DOI: 10.1186/s41927-025-00580-1.
