1. Health Psychology Group, University of Aberdeen, Aberdeen, UK
2. Health Services Research Unit, University of Aberdeen, Aberdeen, UK
3. University College Hospital, London, UK
4. Institute of Health and Society, Newcastle University, Newcastle upon Tyne, UK
5. Lawrence S. Bloomberg Faculty of Nursing, University of Toronto, Toronto, ON, Canada
6. Intensive Care National Audit and Research Centre (ICNARC), London, UK
7. Department of Critical Care Medicine, Sunnybrook Health Sciences Centre, Department of Anaesthesia, University of Toronto, Toronto, ON, Canada