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Collaborative Depression Trial (CADET): multi-centre randomised controlled trial of collaborative care for depression - study protocol

David A Richards1*, Adwoa Hughes-Morley1, Rachel A Hayes1, Ricardo Araya2, Michael Barkham3, John M Bland4, Peter Bower5, John Cape6, Carolyn A Chew-Graham7, Linda Gask5, Simon Gilbody4, Colin Green8, David Kessler9, Glyn Lewis2, Karina Lovell10, Chris Manning11 and Stephen Pilling12

Author Affiliations

1 Mood Disorders Centre, School of Psychology, University of Exeter, EX4 4QG, UK

2 Academic Unit of Psychiatry, University of Bristol, Cotham Hill, BS6 6JL, UK

3 Clinical Psychology Unit, Dept of Psychology, University of Sheffield, S10 2TP, UK

4 Department of Health Sciences, 1st floor, Seebohm Rowntree Building, University of York, Heslington, York, YO10 5DD, UK

5 NPCRDC, Williamson Building, University of Manchester, Oxford Road, Manchester M13 9PL, UK

6 Camden and Islington Mental Health and Social Care Trust, East Wing, St Pancras Hospital, 4 St Pancras Way, London, NW1 0PE, UK

7 University of Manchester, School of Community Based Medicine, Rusholme Academic Unit, Walmer Street, Manchester, M14 5NP, UK

8 Peninsula Medical School, University of Exeter, St Lukes Campus, Exeter EX1 2LU, UK

9 Academic Unit of Primary Health Care, University of Bristol, 25 Belgrave Road, Clifton, Bristol BS8 2AA, UK

10 The School of Nursing, Midwifery and Social Work, University of Manchester, Room 6.322a, Jean McFarlane Building, University Place, Oxford Road, Manchester, M13 9PL, UK

11 Upstream Healthcare Ltd, Unit 5, 2a, Laurel Avenue, Twickenham, TW1 4JA, UK

12 CORE, Clinical Health Psychology, 1-19 Torrington Place, London, WC1E 7HB, UK

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BMC Health Services Research 2009, 9:188  doi:10.1186/1472-6963-9-188

Published: 16 October 2009



Comprising of both organisational and patient level components, collaborative care is a potentially powerful intervention for improving depression treatment in UK primary Care. However, as previous models have been developed and evaluated in the United States, it is necessary to establish the effect of collaborative care in the UK in order to determine whether this innovative treatment model can replicate benefits for patients outside the US. This Phase III trial was preceded by a Phase II patient level RCT, following the MRC Complex Intervention Framework.


A multi-centre controlled trial with cluster-randomised allocation of GP practices. GP practices will be randomised to usual care control or to "collaborative care" - a combination of case manager coordinated support and brief psychological treatment, enhanced specialist and GP communication. The primary outcome will be symptoms of depression as assessed by the PHQ-9.


If collaborative care is demonstrated to be effective we will have evidence to enable the NHS to substantially improve the organisation of depressed patients in primary care, and to assist primary care providers to deliver a model of enhanced depression care which is both effective and acceptable to patients.

Trial Registration Number