[1] NPIS Edinburgh, Edinburgh EH16 3SA, Midlothian, Scotland
[2] Royal Infirm Edinburgh NHS Trust, Edinburgh, Midlothian, Scotland
[3] Univ Bristol, Sch Social & Community Med, Bristol, Avon, England
[4] Guys & St Thomas NHS Fdn Trust & Kings Hlth Partn, London, England
[5] Newcastle Hosp NHS Fdn Trust, Newcastle Upon Tyne, Tyne & Wear, England
[6] Royal Infirm Edinburgh NHS Trust, Dept Emergency Med, Emergency Med Res Grp, Edinburgh, Midlothian, Scotland
[7] Univ Edinburgh, Univ BHF Ctr Cardiovasc Sci, Edinburgh, Midlothian, Scotland
[8] Kings Coll London, London WC2R 2LS, England