Establishment of the Western Japan Psoriasis Registry and first cross-sectional analysis of registered patients.

The efficacy and safety of new psoriatic treatments are confirmed in clinical trials, but such clinical trial data are limited by the number and heterogeneity of patients. Furthermore, the prevalence and characteristics of psoriasis differ among racial groups. Therefore, it is important to obtain real-world evidence in specific regions. To identify the optimal systemic treatment for psoriatic patients in Western Japan, we established the Western Japan Psoriasis Registry (WJPR). This registry is led by a neutral physicians' league associated with university hospitals, general hospitals, and clinics that specialize in treatment of psoriasis. Systemically treated psoriatic patients who provided written informed consent were enrolled, and data were collected on their background information, several patient-reported outcomes, dermatologists' objective evaluations, and treatment regimens. Patient enrollment began in 2019, and 1394 patients had been recruited by the end of 2020. The prevalence of psoriatic arthritis was 27.2% and that of pustular psoriasis was 7.5%. The mean body mass index was 24.1 kg/m2 , and 12% of patients had severe obesity (body mass index ≥30 kg/m2 ). Major comorbidities were hypertension (35.0%), diabetes (14.1%), and hyperlipidemia (12.2%). Serological data showed that hepatitis B virus surface antigen, anti-hepatitis B virus core antibody, anti-hepatitis C virus antibody, and human T-cell leukemia virus type 1 antibody were detected in 1.1%, 18.0%, 3.1%, and 3.7% of patients, respectively. The most frequently used small-molecule-systemic intervention was apremilast (18.0%), followed by methotrexate (7.7%), etretinate (4.2%), and cyclosporin (3.7%). The most frequently used biologics were interleukin (IL)-17 inhibitors (31.8%), followed by IL-23 inhibitors (including IL-12/23 inhibitors) (26.7%), and tumor necrosis factor inhibitors (11.1%). The WJPR is the first Japanese prospective observational cohort of psoriatic patients. Annual WJPR updates may provide the incidences of comorbidities such as cardiovascular events or onset of arthritis in systemically treated patients, identify rare complications, and identify the optimal treatment regimens for various psoriatic patients.