[1] Univ Cambridge, Cambridge, England
[2] Radcliffe Infirm, Clin Trials Serv, Oxford OX2 6HE, England
[3] Univ Birmingham, Clin Trials Unit, Birmingham, W Midlands, England
[4] City Hosp NHS Trust, Birmingham, W Midlands, England
[5] Royal Victoria Infirm, Newcastle Upon Tyne NE1 4LP, Tyne & Wear, England
[6] St Thomas Hosp, London, England
[7] Univ Sheffield, Sheffield, S Yorkshire, England