Disease phenotype and management of axial psoriatic arthritis in Japan compared with other regions, particularly other Asian countries: results of the ASAS-PerSpA study.

BACKGROUND: This study evaluated the disease phenotype and treatment of axial psoriatic arthritis among patients from Japan compared with those from different geographic regions. METHODS: Data from the ASAS-PerSpA study were analyzed. Patients with psoriatic arthritis (PsA) with axial involvement, according to a rheumatologist´s judgment, were included. Patients were further categorized by four geographic regions: Europe/North America, Latin America, Middle East/North Africa, and Asia, split into Japan and other Asian countries. Disease and patient characteristics, disease activity, function, and treatment were compared by region. RESULTS: Of the 4,465 patients with SpA, 1,033 (23%) were diagnosed with PsA by their rheumatologist. Among those with PsA, 367 (35.5%) had axial involvement (axPsA). Disease activity and function ranges were 4.1-5.4 for BASDAI, 2.5-3.2 for ASDAS, and 3.0-4.7 for BASFI, by regions. In Japan, disease activity and function were relatively lower, indicated by a mean BASDAI of 3.5 (SD 2.4), ASDAS of 2.2 (SD 1.0), and BASFI of 1.6 (SD 2.3). These indexes were also significantly lower than those in other Asian countries, with scores of 4.8 (SD 3.0), 2.2 (SD 2.4), and 3.2 (SD 1.5) respectively. All regions showed variations in the use of csDMARDs and bDMARDs, the utilization rate of csDMARDs was significantly lower in Japan than in other Asian countries (51.4% vs. 78.1%, p = 0.02). CONCLUSION: Patients with axPsA in Japan showed relatively lower disease activity and function than those from different geographic regions, especially in other Asian countries with less frequent csDMARD use.