LOOP, a cross-sectional, observational study investigating the clinical specialty setting as a determinant of disease management in psoriatic arthritis: Subgroup analysis results from Japan

BACKGROUND: Psoriatic arthritis (PsA) is a progressive erosive joint disorder that causes functional impairment; therefore, early diagnosis and management are essential. This study evaluated the association between clinical specialty and the time to management in patients with PsA in Japan. METHODS: This was a subgroup analysis of a cross-sectional, multicenter, observational study that was conducted in 17 countries outside the United States, including 17 sites at 8 institutions in Japan, from June 2016 to October 2017. Data from consecutive patients (age ≥18 years) with a suspected or established diagnosis of PsA on a routine visit to a participating rheumatology/orthopedic or dermatology clinic in Japan were analyzed. The primary endpoints were time from onset of inflammatory musculoskeletal symptoms to PsA diagnosis, PsA diagnosis to first conventional synthetic disease-modifying antirheumatic drug (csDMARD), PsA diagnosis to first biologic DMARD (bDMARD), and first csDMARD to first bDMARD. RESULTS: Of 109 patients with a confirmed diagnosis of PsA, 39.4% (n = 43) and 60.6% (n = 66) were recruited by rheumatologists/orthopedists and dermatologists, respectively. Most patients were prescribed tumor necrosis factor inhibitors (58.7%) or methotrexate (56.0%). The mean duration from symptom onset to PsA diagnosis was significantly longer (p = 0.044) for patients treated by rheumatologists/orthopedists (70.6 months) than those treated by dermatologists (30.1 months). In the rheumatology/orthopedic and dermatology settings, the mean time from PsA diagnosis to first csDMARD administration was −0.9 and −2.9 months, and from PsA diagnosis to first bDMARD 21.4 and 14.9 months, respectively. The mean duration from administration of first csDMARD to first bDMARD was comparable in the rheumatology/orthopedic (31.8 months) and dermatology (31.5 months) settings. CONCLUSIONS: Treatment approach was slightly different between rheumatology/orthopedic and dermatology setting in clinical practice in Japan, suggesting that an integrated dermo-rheumatologic approach can optimize the management of patients with PsA.