[1] Charing Cross Hosp, Dept Pharm, London W6 8RF, England
[2] Imperial Coll Healthcare NHS Trust, Ctr Medicat Safety & Serv Qual, London, England
[3] UCL, Clin Operat Res Unit, London, England
[4] Imperial Coll Healthcare NHS Trust, Charing Cross Hosp, London, England
[5] Imperial Coll Healthcare NHS Trust, Hammersmith Hosp, London, England
[6] Univ London, Ctr Medicat Safety & Serv Qual, Sch Pharm, London, England