Researchers from the School of Social and Community Medicine at the University of Bristol in the UK evaluated the effectiveness of CBT (Cognitive Behavioral Therapy) as an adjunct to pharmacotherapy for patients with treatment-resistant depression, as compared to usual care.
This two parallel-group, multicenter, randomized, controlled trial recruited 469 patients with treatment resistant depression, between the ages of 18-75 years, from 73 primary care practices. (The criteria being that they were on antidepressants for at least ≥6 weeks, scored ≥14 on the Beck Depression Inventory [BDI] and scored -10 on depression on the ICD – International Classification of Diseases.)
Participants were randomized, with a computer generated code to one of two groups: usual care or CBT in addition to usual care. They were followed for 12 months. Analyses were by intention to treat. The primary outcome was response, defined as at least 50% reduction in depressive symptoms (BDI score) at 6 months compared with baseline.
Between Nov 4, 2008, and Sept 30, 2010, 235 patients were assigned to usual care, and 234 to CBT plus usual care. There were 422 participants (90%) who were followed up at 6 months, and 396 (84%) at 12 months. Ninety-five participants (46%) in the intervention group met the criteria for response at 6 months, as compared with 46 (22%) in the usual care group (odds ratio 3·26, 95% CI 2·10-5·06, p<0·001).
Before this study, there was no evidence available from large-scale randomized controlled trials for the effectiveness of augmenting antidepressant medication with CBT as a next-step for patients whose depression does not respond to pharmacotherapy. This study has provides robust evidence that CBT as an adjunct to usual care is an effective treatment, reducing depressive symptoms in this population.