Radiographic sacroiliitis progression in axial spondyloarthritis: central reading of 5 year follow-up data from the Assessment of SpondyloArthritis international Society cohort. (12th February 2021) - Protopopov, Mikhail; Proft, Fabian; Sepriano, Alexandre; Landewé, Robert; van der Heijde, Désirée; Maksymowych, Walter P; Baraliakos, Xenofon; Sieper, Joachim; Rudwaleit, Martin; Poddubnyy, Denis