Sex and gender are important factors that influence treatment response in PsA. The goal of this multi-centre observational study is to understand how sex and gender influence response to advanced therapies in psoriatic arthritis (PsA). The investigators hope to discover biological and socio-cultural mechanisms that explain the differences in treatment response between men and women with PsA. The study investigators plan to recruit patients from approximately 30 sites across the world. Men and women with active PsA will be assessed before and after they start advanced therapies and information will be collected about sex- and gender-related factors through questionnaires and physical examination. Physicians will assess the patient response to treatment. The investigators will compare the response to treatment in men and women and assess what biological and socio-cultural factors contribute to differences in treatment response.