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Clinical effectiveness of collaborative care for depression in UK primary care (CADET): cluster randomised controlled trial

BMJ 2013; 347 doi: (Published 19 August 2013) Cite this as: BMJ 2013;347:f4913
  1. David A Richards, professor1,
  2. Jacqueline J Hill, PhD student2,
  3. Linda Gask, professor3,
  4. Karina Lovell, professor4,
  5. Carolyn Chew-Graham, professor5,
  6. Peter Bower, professor6,
  7. John Cape, head of psychology7,
  8. Stephen Pilling, professor7,
  9. Ricardo Araya, professor8,
  10. David Kessler, consultant senior lecturer8,
  11. J Martin Bland, professor9,
  12. Colin Green, professor10,
  13. Simon Gilbody, professor11,
  14. Glyn Lewis, professor12,
  15. Chris Manning, public and patient advocate13,
  16. Adwoa Hughes-Morley, research fellow3,
  17. Michael Barkham, professor14
  1. 1Institute of Health Research, University of Exeter Medical School, Exeter EX1 2LU, UK
  2. 2School of Psychology, University of Exeter, Exeter, UK
  3. 3Centre for Primary Care, Institute of Population Health, Manchester Academic Health Science Centre, Williamson building, University of Manchester, Manchester, UK
  4. 4University of Manchester, School of Nursing, Midwifery & Social Work, Jean McFarlane Building, Manchester, UK
  5. 5Arthritis Research UK Primary Care Centre, Primary Care Sciences, Keele University, Keele, UK
  6. 6NIHR School for Primary Care Research, Centre for Primary Care, Institute of Population Health, Manchester Academic Health Science Centre, University of Manchester, UK
  7. 7Research Department of Clinical, Educational and Health Psychology, University College London, London, UK
  8. 8School of Social and Community Medicine, University of Bristol, Bristol, UK
  9. 9Department of Health Sciences, University of York, York, UK
  10. 10Institute of Health Research, University of Exeter Medical School, University of Exeter, UK
  11. 11Mental Health Research Group, Department of Health Sciences and Hull York Medical School, University of York, UK
  12. 12Mental Health Sciences Unit, University College London, UK
  13. 13Upstream Healthcare, Teddington, UK
  14. 14Centre for Psychological Services Research, Department of Psychology, University of Sheffield, Sheffield, UK
  1. Correspondence to: D A Richards d.a.richards{at}
  • Accepted 26 July 2013


Objective To compare the clinical effectiveness of collaborative care with usual care in the management of patients with moderate to severe depression.

Design Cluster randomised controlled trial.

Setting 51 primary care practices in three primary care districts in the United Kingdom.

Participants 581 adults aged 18 years and older who met ICD-10 (international classification of diseases, 10th revision) criteria for a depressive episode on the revised Clinical Interview Schedule. We excluded acutely suicidal patients and those with psychosis, or with type I or type II bipolar disorder; patients whose low mood was associated with bereavement or whose primary presenting problem was alcohol or drug abuse; and patients receiving psychological treatment for their depression by specialist mental health services. We identified potentially eligible participants by searching computerised case records in general practices for patients with depression.

Interventions Collaborative care, including depression education, drug management, behavioural activation, relapse prevention, and primary care liaison, was delivered by care managers. Collaborative care involved six to 12 contacts with participants over 14 weeks, supervised by mental health specialists. Usual care was family doctors’ standard clinical practice.

Main outcome measures Depression symptoms (patient health questionnaire 9; PHQ-9), anxiety (generalised anxiety disorder 7; GAD-7), and quality of life (short form 36 questionnaire; SF-36) at four and 12 months; satisfaction with service quality (client satisfaction questionnaire; CSQ-8) at four months.

Results 276 participants were allocated to collaborative care and 305 allocated to usual care. At four months, mean depression score was 11.1 (standard deviation 7.3) for the collaborative care group and 12.7 (6.8) for the usual care group. After adjustment for baseline depression, mean depression score was 1.33 PHQ-9 points lower (95% confidence interval 0.35 to 2.31, P=0.009) in participants receiving collaborative care than in those receiving usual care at four months, and 1.36 points lower (0.07 to 2.64, P=0.04) at 12 months. Quality of mental health but not physical health was significantly better for collaborative care than for usual care at four months, but not 12 months. Anxiety did not differ between groups. Participants receiving collaborative care were significantly more satisfied with treatment than those receiving usual care. The number needed to treat for one patient to drop below the accepted diagnostic threshold for depression on the PHQ-9 was 8.4 immediately after treatment, and 6.5 at 12 months.

Conclusions Collaborative care has persistent positive effects up to 12 months after initiation of the intervention and is preferred by patients over usual care.

Trial registration number ISRCTN32829227.


  • Contributors: DAR, LG, KL, CC-G, PB, JC, SP, RA, DK, JMB, CG, SG, GL, CM, and MB designed the study and were responsible for its conduct. JJH and AH-M were responsible for study management and data collection; JMB, CG, DAR, and JJH undertook data analysis. All authors had full access to all of the data (including statistical reports and tables) in the study and can take responsibility for the integrity of the data and the accuracy of the data analysis. All authors contributed to the writing and editing of the manuscript. DAR is guarantor.

  • Funding: This report is independent research funded by the UK Medical Research Council (MRC; reference G0701013), managed by the National Institute for Health Research (NIHR) on behalf of the MRC-NIHR partnership.

  • Competing interests: all authors have completed the ICMJE uniform disclosure form at and declare: all authors had financial support from the NIHR for the submitted work; DAR receives funding support from NIHR Collaborations for Leadership in Applied Health Research and Care; no other relationships or activities that could appear to have influenced the submitted work.

  • Ethical approval: Ethical approval for the study was given by the NHS Health Research Authority, NRES Committee South West (NRES/07/H1208/60). All participants gave informed consent before taking part in the study.

  • Data sharing: patient level data is available from the corresponding author. Consent for data sharing was not obtained but the presented data are anonymised and risk of identification is low.

  • The lead author affirms that this manuscript is an honest, accurate, and transparent account of the study being reported; that no important aspects of the study have been omitted; and that any discrepancies from the study as planned (and, if relevant, registered) have been explained.

This is an Open Access article distributed in accordance with the terms of the Creative Commons Attribution (CC BY 3.0) license, which permits others to distribute, remix, adapt and build upon this work, for commercial use, provided the original work is properly cited. See:

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