Prevalence of psoriatic arthritis in patients with psoriasis: A systematic review and meta-analysis of observational and clinical studies by Alinaghi, F, Calov, M, Kristensen, LE, Gladman, DD, Coates, LC, Jullien, D, Gottlieb, AB, Gisondi, P, Wu, JJ, Thyssen, JP, Egeberg, A