1 Cicely Saunders Institute, Department of Palliative Care, Policy and Rehabilitation, Faculty of Nursing, Midwifery and Palliative Care, King's College London, UK.
2 Biostatistics and Health Informatics, Institute of Psychiatry, Psychology and Neuroscience, King's College London, UK.
3 Wolfson Palliative Care Research Centre, Hull York Medical School, University of Hull, UK.