[1] Barts & London Queen Marys Sch Med & Dent, Dept Gen Practice & Primary Care, London, England
[2] Univ Kent, Ctr Hlth Serv Studies, Canterbury, Kent, England
[3] St George Hosp, Romford Primary Care Grp, Hornchurch, Essex, England
[4] Kings Coll Hosp London, London, England
[5] Royal Natl Orthopaed Hosp, UCL Inst Human Performance, Stanmore HA7 4LP, Middx, England