1. Centre for Primary Care and Public Health, Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK
2. Department of Psychology, Royal Holloway University of London, Egham, UK
3. Exeter Medical School, University of Exeter, Exeter, UK
4. Department of Health Services Research and Policy, London School of Hygiene & Tropical Medicine, London, UK
5. Department of Rheumatology, University College Hospital, University College London, London, UK
6. Clinical Trials Unit, Warwick Medical School, University of Warwick, Coventry, UK