[1] Cardiff Univ, Coll Biomed & Life Sci, Ctr Trials Res, Sch Med, Cardiff, Wales
[2] Univ Bristol, Ctr Acad Primary Care, Bristol Med Sch, Bristol, England
[3] Publ Hlth Wales NHS Trust, Cardiff, Wales
[4] Bangor Univ, Ctr Hlth Econ & Med Evaluat, Bangor, Wales
[5] Cardiff Univ, Coll Biomed & Life Sci, Sch Pharm, Cardiff, Wales
[6] Hlth Educ & Improvement Wales, Cardiff, Wales
[7] Cardiff Univ, Coll Biomed & Life Sci, Sch Med, Div Populat Med, Cardiff, Wales
[8] Cardiff Univ, Coll Biomed & Life Sci, PRIME Ctr Wales, Sch Med, Cardiff, Wales