[1] South London Healthcare NHS Trust, South London, Kent, England
[2] Northumbria Univ, Sch Hlth Community & Educ Studies, Newcastle, Tyne & Wear, England
[3] Univ Hosp Leicester, Pain Management Serv, Leicester, Leics, England
[4] Univ Aberdeen, Ctr Acad Primary Care, Aberdeen, Scotland
[5] Univ Nottingham, Sch Pharm, Nottingham, England
[6] Nottingham Univ Hosp NHS Trust, Pain Management Serv & Pharm Dept, Nottingham, England
[7] Teesside Univ, Hlth & Social Care Inst, Middlesbrough, Cleveland, England
[8] UCL, Res Dept Mental Hlth Sci, Marie Curie Palliat Care Res Unit, Med Sch, London, England
[9] Univ Greenwich, Ctr Hlth & Social Care, London, England