[1] Univ Oxford, Big Data Inst, Ethox Ctr, Nuffield Dept Populat Hlth, Old Rd Campus, Oxford OX3 7LF, England
[2] Great Ormond St Hosp Sick Children, Louis Dundas Ctr Childrens Palliat Care, London, England
[3] Univ Oxford, Uehiro Oxford Inst, Oxford, England
[4] John Radcliffe Hosp, Oxford, England
[5] Wake Forest Univ, Bowman Gray Sch Med, Dept Internal Med, Winston Salem, NC USA
[6] Wake Forest Univ, Ctr Bioeth Hlth & Soc, Winston Salem, NC USA