[1] Oxford Radcliffe Hosp NHS Trust, Dept Hepatobiliary & Pancreat Surg, Churchill Hosp, Oxford OX3 9DU, England
[2] Univ Oxford, Bodleian Hlth Care Libraries, Oxford, England
[3] Univ Oxford, Oxford Int Programme Evidence Based Hlth Care, Oxford, England
[4] Univ Oxford, Dept Primary Hlth Care, Oxford, England
[5] Leicester Gen Hosp, Dept Hepatobiliary & Pancreat Surg, Leicester LE5 4PW, Leics, England