[1] Univ Bristol, Bristol Med Sch, Univ Hosp Bristol NHS Fdn Trust,Quantitat Appl Hl, Populat Hlth Sci,Natl Inst Hlth Res Collaborat Le, Bristol, Avon, England
[2] Univ Bristol, Bristol Med Sch, Univ Hosp Bristol NHS Fdn Trust,Social Sci Qualit, Populat Hlth Sci,Natl Inst Hlth Res Collaborat Le, Bristol, Avon, England
[3] Addict Rehabil Ctr, Bristol, Avon, England
[4] Univ Bristol, Bristol Med Sch, Populat Hlth Sci, Publ Hlth & Epidemiol, Bristol, Avon, England
[5] Univ Bristol, NIHR Hlth Protect Res Unit Fvaluat Intervent, Bristol, Avon, England
[6] Univ Bristol, Populat Hlth Sci, Publ Hlth Res, Bristol Med Sch, Bristol, Avon, England
[7] Univ Hosp Bristol NHS Fdn, Dept Anaesthesia, Neurosci & Anaesthesia, Bristol, Avon, England
[8] Univ Bristol, Sch Physiol Pharmacol & Neurosci, Bristol, Avon, England
[9] Univ Hosp Bristol NHS Fdn Trust, NIHR CLAHRC West, Ethnog, Bristol, Avon, England
[10] Univ Bristol, Bristol Med Sch, Populat Hlth Sci, Bristol, Avon, England
[11] Univ Bristol, Bristol Med Sch, Populat Hlth Sci, Publ Hlth Med, Bristol, Avon, England
[12] South Gloucertershire Council, Bristol, Avon, England