[1] Univ Manchester, Ctr Primary Care & Hlth Serv Res, Suite 6 Williamson Bldg,Oxford Rd, Manchester M13 9QQ, Lancs, England
[2] Univ British Columbia, Fac Pharmaceut Sci, Vancouver, BC, Canada
[3] St Pauls Hosp, Ctr Hlth Evaluat & Outcome Sci, Vancouver, BC, Canada
[4] Univ Manchester, Manchester Ctr Hlth Econ, Manchester, Lancs, England
[5] Univ Manchester, Manchester Inst Educ, Manchester, Lancs, England