Open Access Highly Accessed Open Badges Study protocol

Cost and outcome of behavioural activation versus cognitive behaviour therapy for depression (COBRA): study protocol for a randomised controlled trial

Shelley Rhodes1, David A Richards1*, David Ekers2, Dean McMillan3, Sarah Byford4, Paul A Farrand5, Simon Gilbody3, Steven D Hollon6, Willem Kuyken5, Christopher Martell7, Heather A O’Mahen5, Emer O’Neill8, Nigel Reed9, Rod S Taylor10, Ed R Watkins5 and Kim A Wright5

Author Affiliations

1 University of Exeter Medical School, St Luke’s Campus, Exeter EX1 2 LU, UK

2 Durham University/Tees Esk and Wear Valleys NHS Foundation Trust, Wolfson Research Institute for Health and Wellbeing, Durham University, Queen’s Campus, University Boulevard, Stockton on Tees, Durham TS17 6BH, UK

3 Department of Health Sciences, Seebohm Rowntree Building, University of York, Heslington, York YO10 5DD, UK

4 Institute of Psychiatry, Kings College London, De Crespigny Park, London SE5 8AF, UK

5 School of Psychology, Sir Henry Wellcome Building for Mood Disorders Research, University of Exeter, Streatham Campus, Exeter EX4 4QG, UK

6 Department of Psychology, 306 Wilson Hall, 21st Avenue South, Vanderbilt University, 2301 Vanderbilt Place, Nashville, TN 37240-7817, USA

7 Department of Psychology, University of Wisconsin, Milwaukee, P.O. Box 413, Milwaukee WI 53201, USA

8 Depression Alliance, 20 Great Dover Street, London SE1 4LX, UK

9 Lived Experience Group, c/o School of Psychology, Sir Henry Wellcome Building for Mood Disorders Research, University of Exeter, Streatham Campus, Exeter EX4 4QG, UK

10 University of Exeter Medical School, The Veysey Building, Salmon Pool Lane, Exeter EX2 4SG, UK

For all author emails, please log on.

Trials 2014, 15:29  doi:10.1186/1745-6215-15-29

Published: 21 January 2014



Cognitive behaviour therapy (CBT) is an effective treatment for depression. However, CBT is a complex therapy that requires highly trained and qualified practitioners, and its scalability is therefore limited by the costs of training and employing sufficient therapists to meet demand. Behavioural activation (BA) is a psychological treatment for depression that may be an effective alternative to CBT and, because it is simpler, might also be delivered by less highly trained and specialised mental health workers.


COBRA is a two-arm, non-inferiority, patient-level randomised controlled trial, including clinical, economic, and process evaluations comparing CBT delivered by highly trained professional therapists to BA delivered by junior professional or para-professional mental health workers to establish whether the clinical effectiveness of BA is non-inferior to CBT and if BA is cost effective compared to CBT. Four hundred and forty patients with major depressive disorder will be recruited through screening in primary care. We will analyse for non-inferiority in per-protocol and intention-to-treat populations. Our primary outcome will be severity of depression symptoms (Patient Health Questionnaire-9) at 12 months follow-up. Secondary outcomes will be clinically significant change and severity of depression at 18 months, and anxiety (General Anxiety Disorder-7 questionnaire) and health-related quality of life (Short-Form Health Survey-36) at 12 and 18 months. Our economic evaluation will take the United Kingdom National Health Service/Personal Social Services perspective to include costs of the interventions, health and social care services used, plus productivity losses. Cost-effectiveness will explored in terms of quality-adjusted life years using the EuroQol-5D measure of health-related quality of life.


The clinical and economic outcomes of this trial will provide the evidence to help policy makers, clinicians and guideline developers decide on the merits of including BA as a first-line treatment of depression.

Trial registration

Current Controlled Trials ISRCTN27473954