1. Liverpool Clinical Trials Centre, University of Liverpool, Liverpool, UK
2. Edinburgh Clinical Trials Unit, University of Edinburgh, Edinburgh, UK
3. Clinical Trials Research Unit, University of Leeds, Leeds, UK
4. Nottingham Clinical Trials Unit, University of Nottingham, Nottingham, UK
5. Clinical Trials Research Unit, ScHARR, University of Sheffield, Sheffield, UK
6. Comprehensive Clinical Trials Unit, University College London, London, UK
7. Robertson Centre for Biostatistics, University of Glasgow, Glasgow, UK