1. Oxford National Institute for Health Research (NIHR) Musculoskeletal Biomedical Research Unit, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Oxford, UK
2. Medical Research Council (MRC) Lifecourse Epidemiology Unit, University of Southampton, Southampton General Hospital, Southampton, UK
3. Health Economics Research Centre, Nuffield Department of Population Health, University of Oxford, Oxford, UK
4. GREMPAL Research Group (IDIAP Jordi Gol) and Musculoskeletal Research Unit (Fundació IMIM-Parc Salut Mar), Universitat Autònoma de Barcelona, Barcelona, Spain
5. School of Clinical Sciences, University of Bristol, Southmead Hospital, Bristol, UK
6. Elderly Care Unit, Royal Berkshire Hospital, Reading, UK
7. Nuffield Department of Primary Care Health Sciences, Oxford, UK
8. Unit of Health Care Epidemiology, Nuffield Department of Population Health, University of Oxford, Oxford, UK