1. National Health System Greater Glasgow and Clyde, University of Glasgow, School of Medicine, Dentistry and Nursing, Glasgow, United Kingdom;
2. THIS.Institute–University of Cambridge, Cambridge, United Kingdom; and
3. Department of Medicine,
4. Palliative and Advanced Illness Research Center, and
5. Department of Biostatistics, Epidemiology, and Informatics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania