1. Department of Health Sciences, College of Life Sciences, University of Leicester, Centre for Medicine, Leicester, LE1 7RH, UK
2. THIS Institute (The Healthcare Improvement Studies Institute), University of Cambridge, Cambridge Biomedical Campus, Clifford Allbutt Building, Cambridge CB2 0AH, UK
3. Newcastle University, Institute for Health and Society, National Innovation Centre for Ageing, Level 4 Time Central, Gallowgate, Newcastle upon Tyne, NE1 4BF, UK
4. Department of Geriatric Medicine, Lyon Teaching Hospital, Lyon, France