1 Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Oxford, UK. Electronic address: laura.coates@ndorms.ox.ac.uk.
2 Sorbonne Université, Inserm, Institut Pierre Louis d'Epidémiologie et de Santé Publique, 75013 Paris, France; Rheumatology department, AP-HP, Pitié-Salpêtrière hospital, 75013 Paris, France.