[1] Inst Psychiat, Dept Psychol, Hlth Psychol Sect, London SE1 9RT, England
[2] St Thomas Hosp, Guys & St Thomas Hosp NHS Trust, London SE1 7EH, England
[3] Univ Leeds, Sch Med, Acad Unit Psychiat & Behav Sci, Leeds LS2 9JT, W Yorkshire, England
[4] UCL, Subdept Clin Hlth Psychol, London WC1E 6BT, England
[5] Brighton Univ, Postgrad Med Sch, Ctr Hlth Care Res, Brighton BN1 9PH, E Sussex, England