[1] R&D Spenshult, Halmstad, Sweden
[2] Halmstad Univ, Sch Hlth & Welf, Halmstad, Sweden
[3] Karolinska Inst, Inst Environm Med, Stockholm, Sweden
[4] Keele Univ, Res Inst Primary Care & Hlth Sci, Keele, Staffs, England
[5] Midlands Partnership NHS Fdn Trust, Stafford, England
[6] Univ Oxford, CSM, NDORMS, Oxford, England
[7] Keele Univ, Ctr Prognosis Res, Keele, Staffs, England
[8] Univ Southern Denmark, Dept Reg Hlth Res, Odense, Denmark
[9] Univ Gothenburg, Inst Med, Gothenburg, Sweden