[1] Univ Manchester, Sch Med, Manchester M13 9PL, Lancs, England
[2] Arthrit Res UK Primary Care Ctr, Keele, Staffs, England
[3] Univ Manchester, Sch Social Sci, Manchester, Lancs, England
[4] Univ Hosp South Manchester NHS Trust, Dept Care Elderly, Manchester, Lancs, England
[5] Keele Univ, Sch Med, Keele ST5 5BG, Staffs, England