[1] Univ Birmingham, Coll Med & Dent Sci, Sch Hlth & Populat Sci, Birmingham B15 2TT, W Midlands, England
[2] Manchester Metropolitan Univ, Fac Hlth Psychol & Social Care, Dept Profess Registrat, Manchester M13 0JA, Lancs, England
[3] UCL Med Sch, Dept Primary Care & Populat Hlth, London NW3 2PF, England