[1] Univ Manchester, Manchester Acad Hlth Sci Ctr, North West Hub Trials Methodol, Williamson Bldg, Manchester M13 9PL, Lancs, England
[2] Queens Univ, Ctr Publ Hlth, Northern Ireland Methodol Hub, Belfast BT12 6BJ, Antrim, North Ireland
[3] Univ Nottingham, Queens Med Ctr, Fac Med & Hlth Sci, Nottingham Clin Trials Unit, Nottingham NG7 2UH, England
[4] Bangor Univ, NWORTH Clin Trials Unit, Bangor LL57 2PZS, Gwynedd, Wales