[1] Royal Devon Healthcare Trust, Dept Gen Surg, Barnstaple, England
[2] Sheffield Teaching Hosp, Dept Surg, Sheffield, England
[3] Kleijnen Systemat Reviews Ltd, York, England
[4] Univ Nottingham, Royal Derby Hosp, Nottingham, England
[5] Royal Derby Hosp, Dept Surg, Derby, England
[6] Univ Hosp, Southampton, England
[7] Chelsea & Westminster Hosp NHS Fdn Trust, Dept Colorectal Surg, London, England
[8] Imperial Coll London, Dept Canc & Surg, London, England
[9] Churchill Hosp, Dept Colorectal Surg, Oxford, England
[10] Royal Devon Healthcare Trust, Pharm Dept, Southampton, England
[11] Univ Hosp, Dept Paediat Surg, Southampton, England
[12] London North West Univ Healthcare Trust, St Marks Hosp, Harrow, England
[13] Univ Coll London Med Sch, UCL Res Dept Primary Care & Populat Hlth, Royal Free Hosp Campus, London, England
[14] St Marks Hosp, Harrow, England