To estimate the real-world effectiveness of approved biologics in subjects with moderate-to-severe plaque psoriasis who are either starting or switching biologic medication.

Plaque psoriasis is a chronic skin disease affecting 1-3% of US and European populations and severely impairs quality of life. Four biologics are authorized in Europe and the US for treatment of patients with moderate to severe psoriasis. Because complete skin clearance is rare with these agents, the treatment goal adopted by regulatory and reimbursement agencies is the proportion of patients achieving at least a 75% reduction from the subject's baseline PASI (Psoriasis Area and Severity Index) score or similarly, a sPGA [static Physician's Global Assessment) score of 0 or 1. Specifically, this study will provide information on the effectiveness of approved biologics as they are used in clinical practice. This information is currently not consistently available from other sources, including existing psoriasis patient registries.

Study Hypothesis: This study will estimate in each country the proportion of biologic treatment-naïve and biologic treatment-switching psoriasis subjects in the real-world having total clearance at 6 months after initiating a biologic.

The study population will include up to approximately 300 adults in each of up to 6 participating countries who have been diagnosed by their physicians with moderate to severe plaque psoriasis, and are initiating biologic therapy(biologic treatment-naïve or biologic treatment-switching) for plaque psoriasis.

Summary of Subject Eligibility Criteria: aged 18 or over; diagnosed with moderate to severe plaque psoriasis; initiating a biologic approved for psoriasis at study entry; able to fill out questionnaires; provided written informed consent; and not participating in a clinical trial utilizing an investigational agent in the 3 months prior to the first biologic dose.

Assessments: Skin clearance is the primary indicator of treatment effectiveness, and will be measured using the physician-reported PASI and sPGA. Other assessments will be by the following patient questionnaires: psoriasis symptom inventory (PSI), the dermatology life quality index (DLQI), the static patient's global assessment ( sPtGA), treatment satisfaction and global health status.

All subjects will be initiating biologic therapy at study entry. Therapy discontinuations, switches, and dosing changes during follow-up will be reported by the site and summarized.

Follow-up continues for approximately 12 months after first dose or until the subject is lost to follow-up or withdraws from the study (for any reason including death), whichever comes first. Where appropriate, data will be obtained for each subject during mandatory visits at 6 months (± 6 weeks) and 12 months (± 6 weeks) after first biologic dose, and at routine visits that occur during the follow-up period. To the extent possible data will also be collected at other usual care visits that occur during follow-up.](streamdown:incomplete-link)

Inclusion Criteria:

• subjects who are greater than or equal to 18 YO diagnosed with moderate to severe plaque psoriasis
• subjects who will be initiating therapy with a biologic approved for moderate to severe psoriasis either for the first time (biologic treatment naive) or in course of switching to a different biologic agent
• subject who is able to complete questionnaires
• subject able to provide written informed consent

Exclusion Criteria:

- subjects who are participating in a clinical trial utilizing an investigational agent in the 3 months prior to the first biologic dose on study

Adults greater than or equal to 18 years of age who have been diagnosed with moderate to severe plaque psoriasis based on treating physician's judgment