1 Nuffield Department of Orthopaedic Rheumatology and Musculoskeletal Sciences, Oxford Clinical Trials Research Unit, Centre for Statistics and Medicine, University of Oxford, Oxford, UK. melina.dritsaki@ndorms.ox.ac.uk.
2 Nuffield Department of Population Health, Health Economics Research Centre, University of Oxford, Oxford, UK.
3 Division of Health Sciences, Warwick Medical School, University of Warwick, Coventry, UK.
4 Nuffield Department of Orthopaedic Rheumatology and Musculoskeletal Sciences, Oxford Clinical Trials Research Unit, Centre for Statistics and Medicine, University of Oxford, Oxford, UK.
5 School of Social and Community Medicine, University of Bristol, Bristol, UK.