[1] Brighton & Sussex Med Sch, Dept Primary Care & Publ Hlth, Mayfield House,Falmer Campus, Brighton BN1 9PH, E Sussex, England
[2] Univ Sheffield, Acad Unit Primary Med Care, Primary Med Care, Sheffield, S Yorkshire, England
[3] Newcastle Univ, Sch Med, Sch Med Educ, Primary & Community Care, Newcastle Upon Tyne NE1 7RU, Tyne & Wear, England
[4] UCL, Dept Primary Care & Populat Hlth, Gen Practice, London WC1E 6BT, England
[5] UCL, Dept Primary Care & Populat Hlth, Community Based Teaching, London WC1E 6BT, England