1 Centre for OA Pathogenesis Versus Arthritis, Kennedy Institute of Rheumatology, University of Oxford, Oxford, UK. Electronic address: Tonia.vincent@kennedy.ox.ac.uk.
2 Leeds Institute of Rheumatic and Musculoskeletal Medicine, University of Leeds, and NIHR Leeds Biomedical Research Centre, Leeds, UK. Electronic address: p.conaghan@leeds.ac.uk.