1. Rheumatology Department, University Hospital of Amiens, University of Picardie Jules Verne, Amiens, France, and Leeds Institute of Rheumatic and Musculoskeletal Medicine, University of Leeds, UK.
2. Leeds Institute of Rheumatic and Musculoskeletal Medicine, University of Leeds, and NIHR Leeds Biomedical Research Centre, Leeds Teaching Hospitals Trust, Leeds, UK.
3. Leeds Institute of Health Sciences and statistics, The University of Leeds, UK.
4. Leeds Institute of Rheumatic and Musculoskeletal Medicine, University of Leeds, UK. f.ponchel@leeds.ac.uk, mmefp@leeds.ac.uk
5. Rheumatology Department, University Hospital of Amiens, University of Picardie Jules Verne, Amiens, France.