A Study to Characterize Profile of Participant With Psoriatic Arthritis Depending on Whether Their Disease is Managed by a Dermatologist or by a Rheumatologist, and Starting Ustekinumab

All participants will receive ustekinumab at study entry. Ustekinumab will not be provided by the sponsor. The treatment decision must have been taken by the investigator prior to, and independently of the participant's inclusion into the study following the standard clinical practice. Only data available from a participant's source medical records will be collected.