Efficacy and safety of upadacitinib in patients with active psoriatic arthritis and axial involvement: results from two phase 3 studies - Baraliakos, X; Ranza, R; Östör, A; Ciccia, F; Coates, LC; Rednic, S; Walsh, JA; Douglas, K; Gao, T; Kato, K; Song, I-H; Ganz, F; et al. (Arthritis Research and Therapy, 2023)