The purpose of this study is to understand current real-world treatment patterns and clinical outcomes, reasons for switching treatment, and participant characteristics using each systemic psoriasis treatment in Japan.

Inclusion Criteria:

• Diagnosis of psoriasis
• Can be followed for at least 2 years
• Treated with any of the following systemic therapy for psoriasis at time of follow-up start: Tumor Necrosis Factor (TNF) inhibitors (infliximab, adalimumab, and certolizumab pegol), Interleukin (IL)-12/23 inhibitors (ustekinumab), IL-23 inhibitors(guselkumab, risankizumab, and tildrakizumab), IL-17 inhibitors (secukinumab, ixekizumab, and brodalumab), Apremilast, Methotrexate, Cyclosporine, Etretinate

Exclusion Criteria:

• Enrolled in any clinical trials for psoriasis in their follow-up period
• Developed psoriatic arthritis, guttate psoriasis, erythrodermic psoriasis, and pustular psoriasis at time of start date
• Treated with any of the following systemic therapy before they were diagnosed with psoriasis: TNF inhibitors (infliximab, adalimumab, and certolizumab pegol), IL-12/23 inhibitors (ustekinumab), IL-23 inhibitors(guselkumab, risankizumab, and tildrakizumab), IL-17 inhibitors (secukinumab, ixekizumab, and brodalumab), Apremilast, Methotrexate, Cyclosporine, Etretinate

120 participants, from 2 to 4 institutes which have a central role of psoriasis therapy in Japan, will be entered into the study if they started systemic treatment after 01/01/2017 and followed until either 12/31/2020, death, or lost to follow-up, whichever occurs first.