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

D. A. Richards, K. Lovell, S. Gilbody, L. Gask, D. Torgerson, M. Barkham, M. Bland, P. Bower, A. J. Lankshear, A. Simpson, J. Fletcher, D. Escott, S. Hennessy, R. Richardson

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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 % Cl -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.

Original languageEnglish
Pages (from-to)279-287
Number of pages9
JournalPsychological Medicine
Issue number2
Publication statusPublished - Feb 2008


  • collaborative care
  • complex intervention
  • depression
  • primary care
  • randomized controlled trial

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