[1] UCL, Res Dept Clin Educ & Hlth Psychol, Ctr Outcomes Res Effectiveness, London WC1E 7HB, England
[2] Univ Exeter, Univ Exeter Med Sch, Exeter EX1 2LU, Devon, England
[3] Univ Aberdeen, Inst Appl Sci, Coll Life Sci & Med, Aberdeen Hlth Psychol Grp, Aberdeen AB25 2ZD, Scotland
[4] City Univ London, Div Hlth Serv Res & Management, London EC1V 0HB, England
[5] Univ Cambridge, Cambridge Inst Publ Hlth, Behav Sci Grp, Primary Care Unit, Cambridge CB2 0SR, England
[6] Newcastle Univ, Inst Hlth & Soc, Newcastle Upon Tyne NE2 4AA, Tyne & Wear, England
[7] Univ Kent, Sch Psychol, Keynes Coll, Canterbury CT2 7NP, Kent, England