[1] UCL, Ctr Behav & Social Sci Med, London W1W 7EJ, England
[2] NE London Mental Hlth Trust, London, England
[3] Univ E Anglia, Sch Med Hlth Policy & Practice, Norwich NR4 7TJ, Norfolk, England
[4] Univ Aberdeen, Dept Gen Practice & Primary Care, Aberdeen AB25 2AY, Scotland
[5] Univ E Anglia, Sch Allied Hlth Profess, Norwich NR4 7TJ, Norfolk, England