1. Warwick Clinical Trials Unit, Warwick Medical School, The University of Warwick, Gibbet Hill Campus, Coventry, UK.
2. Nuffield Department of Primary Care Health Sciences, University of Oxford, Oxford, UK.
3. Oxford Trauma, Nuffield Department of Orthopaedics, Rheumatology & Musculoskeletal Sciences, University of Oxford, Oxford, UK.
4. Statistics and Epidemiology Unit, Warwick Medical School, The University of Warwick, Gibbet Hill Campus, Coventry, UK.
5. University Hospitals Coventry and Warwickshire NHS Trust, Clifford Bridge Road, Coventry, UK.