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Cognitive behavioural therapy as an adjunct to pharmacotherapy for treatment resistant depression in primary care: a randomised controlled trial
ISRCTN ISRCTN38231611
DOI 10.1186/ISRCTN38231611
ClinicalTrials.gov identifier
EudraCT number
Public title Cognitive behavioural therapy as an adjunct to pharmacotherapy for treatment resistant depression in primary care: a randomised controlled trial
Scientific title
Acronym COBALT
Serial number at source HTA 06/404/02
Study hypothesis To determine the clinical and cost-effectiveness of Cognitive Behavioural Therapy (CBT) in addition to pharmacotherapy in reducing depressive symptoms and improving quality of life over the following 12 months (compared to pharmacotherapy plus usual care) in patients with Treatment Resistant Depression (TRD)

In addition, a qualitative study will be conducted to:
1. Explore patient's views and experiences of CBT
2. Identify patient's reasons for completing or not completing therapy
3. To describe "usual care" for this patient group

Added as of 19/02/2013: In addition, to determine whether the intervention is effective in reducing depressive symptoms and improving quality of life over the long-term (approximately 4 years post-randomisation), compared with usual care alone, and whether this strategy is cost-effective

Please note that as of 19/02/2013, the anticipated end date for this trial was updated from 31/01/2012 to 31/08/2014
Lay summary Not provided at time of registration
Ethics approval West Midlands Research Ethics Committee gave approval on the 26th Feburary 2008 (ref: 07/H1208/60)
Study design Multi-centre, randomised controlled trial.
Countries of recruitment United Kingdom
Disease/condition/study domain Depression
Participants - inclusion criteria 1. Aged 18-75 years
2. Patients currently taking antidepressant medication and who have done so for at least 6 weeks at an adequate dose
3. Patients who score 14 or more on the Beck Depression Inventory (BDI)
4. Have adhered to their medication
5. Meet the World Health Organization International Statistical Classification of Diseases and Related Health Problems 10th Revision (ICD-10) criteria for depression
Participants - exclusion criteria 1. Bipolar disorder
2. Psychosis or alcohol/substance abuse/dependence
3. Not able to complete the study questionnaires
4. Currently receiving CBT or other psychotherapy or secondary care for depression
5. Have received CBT in the past 3 years
6. Patients who would not be able to benefit from talking therapy without an interpreter
7. Women who are pregnant at time of recruitment will be excluded from the trial but women who become pregnant during the trial may continue, providing they have approval and permission to do so from their GP
Anticipated start date 01/05/2008
Anticipated end date 31/08/2014
Status of trial Ongoing
Patient information material Not available in web format, please use the contact details below to request a patient information sheet
Target number of participants 480
Interventions 30/04/2013: Please note that follow-up of trial participants is on-going but recruitment to this trial has now closed.

Patients will be randomised to one of two groups. All patients will be taking antidepressants at the point of randomisation. Both groups will continue their antidepressants as directed by their GP.

In Group 1 (intervention group), subjects will be randomised to receive CBT in addition to usual care (including pharmacotherapy). Each patient will receive a course of 12-18 sessions of CBT.

In Group 2 (control group), subjects would continue to receive their usual care from their GP (including antidepressants).
Primary outcome measure(s) BDI score at 6-months post-randomisation, specifically a binary variable representing response, defined as a reduction in depressive symptoms of at least 50% compared to baseline.
Secondary outcome measure(s) Current secondary outcome measures as of 19/02/2013:
Remission of symptoms, quality of life and use of antidepressants at 6 months post-randomisation, together with outcomes measured at 12 months post-randomisation and long-term outcomes measured approximately 4 years post-randomisation.

Previous secondary outcome measures until 19/02/2013:
Remission of symptoms, quality of life and use of antidepressants at 6 months post-randomisation, together with outcomes measured at 12 months post-randomisation.
Sources of funding NIHR Health Technology Assessment Programme - HTA (UK)
Trial website
Publications 2012 protocol in: http://www.ncbi.nlm.nih.gov/pubmed/22101205
2013 results in: http://www.ncbi.nlm.nih.gov/pubmed/23219570
2014 results in: http://www.ncbi.nlm.nih.gov/pubmed/24824481
Contact name Dr  Nicola  Wiles
  Address Centre for Mental Health, Addiction and Suicide Research
School of Social and Community Medicine
University of Bristol
Oakfield House
Oakfield Grove
Clifton
  City/town Bristol
  Zip/Postcode BS8 2BN
  Country United Kingdom
  Tel +44 (0)117 331 3358
  Fax +44 (0)117 331 4026
  Email nicola.wiles@bristol.ac.uk
Sponsor University of Bristol (UK)
  Address c/o Dr Birgit Whitman
Research Governance and Compliance Manager
University of Bristol
Research and Enterprise Development
Senate House
Tyndall Avenue
  City/town Bristol
  Zip/Postcode BS8 1TH
  Country United Kingdom
  Tel +44 (0)117 331 7130
  Fax +44 (0)117 929 8383
  Email Birgit.Whitman@bristol.ac.uk
Date applied 14/08/2007
Last edited 16/05/2014
Date ISRCTN assigned 15/08/2007
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