Psychological Medicine

Original Articles

Collaborative care for depression in UK primary care: a randomized controlled trial

D. A. Richardsa1 c1, K. Lovella2, S. Gilbodya1, L. Gaska3, D. Torgersona1, M. Barkhama4, M. Blanda1, P. Bowera3, A. J. Lanksheara5, A. Simpsona1, J. Fletchera2, D. Escotta2, S. Hennessya1 and R. Richardsona1

a1 Department of Health Sciences, University of York, UK

a2 Department of Nursing, Midwifery and Social Work, University of Manchester, UK

a3 National Primary Care Research and Development Centre, University of Manchester, UK

a4 Centre for Psychotherapy Services Research, University of Sheffield, UK

a5 School of Nursing and Midwifery Studies, University of Cardiff, UK


Background Collaborative care is an effective intervention for depression which includes both organizational and patient-level intervention components. The effect in the UK is unknown, as is whether cluster- or patient-randomization would be the most appropriate design for a Phase III clinical trial.

Method We undertook a Phase II patient-level randomized controlled trial in primary care, nested within a cluster-randomized trial. Depressed participants were randomized to ‘collaborative care’ – case manager-coordinated medication support and brief psychological treatment, enhanced specialist and GP communication – or a usual care control. The primary outcome was symptoms of depression (PHQ-9).

Results We recruited 114 participants, 41 to the intervention group, 38 to the patient randomized control group and 35 to the cluster-randomized control group. For the intervention compared to the cluster control the PHQ-9 effect size was 0.63 (95% CI 0.18–1.07). There was evidence of substantial contamination between intervention and patient-randomized control participants with less difference between the intervention group and patient-randomized control group (−2.99, 95% CI −7.56 to 1.58, p=0.186) than between the intervention and cluster-randomized control group (−4.64, 95% CI −7.93 to −1.35, p=0.008). The intra-class correlation coefficient for our primary outcome was 0.06 (95% CI 0.00–0.32).

Conclusions Collaborative care is a potentially powerful organizational intervention for improving depression treatment in UK primary care, the effect of which is probably partly mediated through the organizational aspects of the intervention. A large Phase III cluster-randomized trial is required to provide the most methodologically accurate test of these initial encouraging findings.

(Received February 05 2007)

(Revised June 05 2007)

(Accepted June 22 2007)

(Online publication September 06 2007)


c1 Address for correspondence: Professor D. A. Richards, Department of Health Sciences, Seebohm Rowntree Building, University of York, University Road, Heslington, York, North Yorkshire, United Kingdom. (Email: