1 National Collaborating Centre for Mental Health, Royal College of Psychiatrists, London E1 8AA, UK Sheffield Health and Social Care NHS Foundation Trust, Sheffield S10 3TH, UK tim2.kendall@virgin.net.
2 Psychiatry and Applied Psychology, Faculty of Medicine and Health Sciences, University of Nottingham, Nottingham, UK.
3 Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA.
4 National Collaborating Centre for Mental Health, University College London, London, UK Centre for Outcomes Research and Effectiveness, University College London, London, UK.