1. Centre for Ageing Population Studies, Research Department of Primary Care and Population Health, University College London, London, UK
2. PRIMENT Clinical Trials Unit, Research Department of Primary Care and Population Health, University College London, London, UK
3. Marie Curie Palliative Care Research Department, Division of Psychiatry, University College London, London, UK
4. Department of Psychological Medicine, Royal London Hospital, East London NHS Foundation Trust, London, UK