1 Rheumatology Department, Research Units EA 4666 & Inserm U1088, Amiens University Hospital, University of Picardie Jules-Verne, 80054 Amiens, France.
2 Rheumatology Department, Strasbourg University Hospital, Strasbourg, France.
3 Leeds Institute of Rheumatic and Musculoskeletal Medicine, The University of Leeds, Leeds, UK.