[1] Univ Cambridge, Primary Care Unit, Cambridge, England
[2] Queen Edith Med Practice, Cambridge, England
[3] Imperial Coll Healthcare NHS Trust, London, England
[4] Hinchingbrooke Hlth Care NHS Trust, Dept Med, Hinchingbrooke, Cambs, England
[5] Univ Cambridge, Sch Clin Med, Cambridge, England
[6] Univ Cambridge, Primary Care Unit, Gen Practice Educ Grp, Cambridge, England