[1] Univ Warwick, Div Hlth Sci, Warwick Clin Trials Unit, Coventry CV4 7AL, W Midlands, England
[2] John Radcliffe Hosp, Oxford Univ Hosp NHS Trust, Headley Way, Headington OX3 9DU, Oxon, England
[3] Royal Devon & Exeter Hosp, Barrack Rd, Exeter EX2 5DW, Devon, England
[4] Univ Hosp Coventry & Warwickshire, Clifford Bridge Rd, Coventry CV2 2DX, W Midlands, England
[5] Newcastle Upon Tyne Hosp NHS Fdn Trust, Falls & Syncope Serv, Newcastle NE1 4LP, England
[6] St Thomas Hosp, Guys & St Thomas NHS Fdn Trust, London SE1 7EH, England
[7] Univ Oxford, Nuffield Dept Orthopaed Rheumatol & Musculoskelet, Botnar Res Ctr, Windmill Rd, Oxford OX3 7LD, England