[1] Keele Univ, Ctr Musculoskeletal Hlth Res, Sch Med, Keele, England
[2] Keele Univ, Ctr Prognosis Res, Keele Cardiovasc Res Grp, Keele, England
[3] Queens Univ Belfast, Ctr Publ Hlth, Belfast, North Ireland
[4] Univ Oxford, Nuffield Dept Primary Care Hlth Sci, Oxford, England
[5] Keele Univ, Sch Pharm & Bioengn, Keele, England
[6] Univ Bristol, Bristol Med Sch, Ctr Acad Primary Care, Bristol, England
[7] Keele Univ, David Weatherall Bldg, Keele ST5 9BG, England