Cross-sectional multicenter observational study of psoriatic arthritis in Japanese patients: Relationship between skin and joint symptoms and results of treatment with tumor necrosis factor-α inhibitors.

Psoriatic arthritis (PsA) is an inflammatory arthritis with as yet unclear pathophysiology. This retrospective, multicenter, cross-sectional study was conducted in 19 facilities in western Japan and aimed to identify patients' characteristics and factors that affect the results of treatment with biologic agents. Of 2116 patients with psoriasis, 285 (13.5%) had PsA. Skin manifestations preceded joint manifestations in 69.8%, the onset was simultaneous in 17.2%, whereas PsA preceded skin manifestations in 2.5%. Peripheral arthritis was most common, occurring in 73.7%, compared with axial disease in 21.8%, enthesitis in 23.5% and dactylitis in 35.4%. Patients with severe skin manifestations were significantly younger at onset (P = 0.02) and more frequently had axial disease (P < 0.01). Biologic agents were used in 206 patients (72.3%), anti-tumor necrosis factor (TNF)-α antibodies being prescribed first to 157 of them. Anti-TNF-α antibodies were continued by 105 participants and discontinued by 47, the remaining five patients being lost to follow up. Patients who discontinued anti-TNF-α antibodies were significantly older than those who continued (55 vs 51 years, P = 0.04) and significantly older at onset of joint manifestations (50 vs 44 years, P = 0.01). Multivariate analysis revealed that patients over 50 years significantly more frequently terminated anti-TNF-α antibodies (P < 0.01). In conclusion, patients with PsA and severe skin manifestations have earlier onset and axial disease, which seriously impacts on quality of life. Anti-TNF-α antibodies were generally effective enough to continue but less so in patients aged over 50 years. Further detailed research is needed.