Psoriatic arthritis (PsA) is a seronegative inflammatory spondylarthritis associated with psoriasis (PsO), which can cause pain and swelling in the joints, sausage-shaped swelling of the fingers and toes (dactylitis), inflammation of the muscle- or tendon insertions at adjacent bone (enthesitis), as well as raised red patches or various other expressions of psoriasis on the skin. Guselkumab (TREMFYA) is a fully human immunoglobulin G1 lambda (IgG1) monoclonal antibody (mAb) that binds to the p19 subunit of human interleukin (IL) 23 with high specificity and affinity, blocking IL-23 binding. Binding of guselkumab to the IL-23p19 subunit blocks the subsequent binding of extracellular IL-23 to the cell surface IL-23 receptor, inhibiting IL-23 specific intracellular signaling and subsequent activation and cytokine production. Participants with confirmed diagnosis of PsA who are starting guselkumab or any marketed interleukin-17 inhibitor (IL-17i) as a first, second, third, or fourth line of PsA biologic therapy per standard clinical practice will be enrolled in the main study. The aim of main study is to document the use of guselkumab and approved IL-17i therapies in routine clinical practice in patients with PsA who are starting guselkumab or an IL-17i as a first, second, third, or fourth line of biologic disease-modifying antirheumatic drugs (bDMARD) therapy. The overall duration of the main study, including recruitment and follow-up, is expected to be about 6 years. Participants who are starting guselkumab or an IL-17i treatment per routine clinical practice in the main study, and who meet the selection criteria for both the main study and substudy, will be consecutively offered entry into the substudy (a select number) at the time of enrollment into the main study. The substudy aims to collect additional data, continuously or with increased frequency, on the impact of guselkumab or IL-17i on patient mood, physical activity, sleep disturbance, disease symptoms, and health-related quality-of-life (HRQoL). Total duration of the substudy will be approximately 26-30 weeks consisting of a pre-treatment period of up to 14 days before the first dose of guselkumab or IL-17i in the main study and a 24-week (plus [+] up to 4 weeks follow-up) observation period.

Psoriatic arthritis (PsA) is a seronegative inflammatory spondylarthritis associated with psoriasis (PsO), which can cause pain and swelling in the joints, sausage-shaped swelling of the fingers and toes (dactylitis), inflammation of the muscle- or tendon insertions at adjacent bone (enthesitis), as well as raised red patches or various other expressions of psoriasis on the skin. Guselkumab (TREMFYA) is a fully human immunoglobulin G1 lambda (IgG1) monoclonal antibody (mAb) that binds to the p19 subunit of human interleukin (IL) 23 with high specificity and affinity, blocking IL-23 binding. Binding of guselkumab to the IL-23p19 subunit blocks the subsequent binding of extracellular IL-23 to the cell surface IL-23 receptor, inhibiting IL-23 specific intracellular signaling and subsequent activation and cytokine production. Participants with confirmed diagnosis of PsA who are starting guselkumab or any marketed interleukin-17 inhibitor (IL-17i) as a first, second, third, or fourth line of PsA biologic therapy per standard clinical practice will be enrolled in the main study. The aim of main study is to document the use of guselkumab and approved IL-17i therapies in routine clinical practice in patients with PsA who are starting guselkumab or an IL-17i as a first, second, third, or fourth line of biologic disease-modifying antirheumatic drugs (bDMARD) therapy. The overall duration of the main study, including recruitment and follow-up, is expected to be about 6 years. Participants who are starting guselkumab or an IL-17i treatment per routine clinical practice in the main study, and who meet the selection criteria for both the main study and substudy, will be consecutively offered entry into the substudy (a select number) at the time of enrollment into the main study. The substudy aims to collect additional data, continuously or with increased frequency, on the impact of guselkumab or IL-17i on patient mood, physical activity, sleep disturbance, disease symptoms, and health-related quality-of-life (HRQoL). Total duration of the substudy will be approximately 26-30 weeks consisting of a pre-treatment period of up to 14 days before the first dose of guselkumab or IL-17i in the main study and a 24-week (plus \[+\] up to 4 weeks follow-up) observation period.