Response to Upadacitinib of Enthesitis Evaluated by Ultrasound in Patients With Psoriatic Arthritis

Primary objective To evaluate the peripheral enthesitis response to upadacitinib treatment by BMUS and DMUS, in PsA patients at week 24. Secondary objective: 1. To evaluate the peripheral enthesitis response to upadacitinib treatment by BMUS and DMUS, in PsA patients at week 12. 2. To evaluate the clinical response of enthesitis to upadacitinib by LEI, at week 12 and week 24. 3. To evaluate the clinical response of disease activity by DAPSA, at week 12 and week 24. Study Design: single-arm, observational longitudinal, prospective study Population: The study population will consist of adult patients (aged ≥ 18 years old and ≤ 65 years old) with PsA according to CASPAR classification criteria, who have been prescribed upadacitinib over the course of routine practice, in accordance with the applicable approved label and local regulatory and reimbursement policies ("In patients with psoriatic arthritis, upadacitinib would be a therapeutic alternative after failure, inadequate response or intolerance to csDMARDs and anti-TNF") and have at least one ultrasound-determined peripheral enthesitis.