Do Patients with non-radiographic axial spondyloarthritis differ from patients with ankylosing spondylitis in several aspects - Kiltz, U; Baraliakos, X; Karakostas, P; Igelmann, M; Kalthoff, L; Klink, C; Krause, D; Schmitz-Bortz, E; Flörecke, M; Bollow, M; Braun, J (Arthritis Care Res (Hoboken), 2012)