[1] Univ Manchester, Sch Nursing Midwifery & Social Work, Manchester, Lancs, England
[2] Univ Manchester, MIMIT, Manchester, Lancs, England
[3] Glasgow Caledonian Univ, Sch Hlth & Life Sci, Glasgow G4 0BA, Lanark, Scotland
[4] Univ Manchester, Arthrit Res UK Epidemiol Unit, Manchester, Lancs, England