CBT is as effective as continued antidepressant treatment in preventing subsequent relapse, a meta-analysis has found.

Nine studies with a total of 506 participants met the inclusion criteria; seven were from the USA, one from the UK and one from Romania. The average Hamilton Depression Rating Scale scores at recruitment ranged from 18.4 to 26.9, indicating moderate to severe depression. Patients were randomised to receive either CBT (18-24 sessions) or antidepressants during the acute phase (12-16 weeks).

CBT was not continued during the follow-up period, although a maximum of five booster sessions were allowed. Antidepressant treatment was either continued during the follow-up period, or withdrawn.

In comparison with patients whose antidepressant treatment was withdrawn, patients treated with CBT were significantly less likely to relapse during the subsequent 12 months, odds ratio (OR) 2.61 (95% CI:1.58-4.31, P < 0.001); number needed to treat (NNT) = 5. There was no significant difference between CBT and continued antidepressant treatment, although the trend favoured the former OR 1.62 (95% CI:0.97-2.72, P < 0.1); NNT = 10.

The British Association for Psychopharmacology guideline concluded that it was difficult to determine the relative efficacy of acute phase CBT and continued antidepressant treatment in preventing depression relapse.1 The authors of this study came to the same conclusion: the studies included were small and insufficiently powered to demonstrate a clinically significant difference between the two alternatives.

Furthermore, we should be cautious when extrapolating results from secondary care clinical trials to real world primary care settings. One of the main reasons for poor outcomes in depression is early cessation of treatment: less than a third of patients complete a six-month course of antidepressant treatment.² Thus, when choosing between CBT and antidepressant therapy, it can be argued that the valid comparison is with discontinued antidepressant therapy and that CBT is the best option.

There are a number of reasons why we may wish to refer patients for CBT:

• As an alternative to antidepressant treatment for patients with persistent mild to moderate depression¹

• In combination with antidepressant treatment for patients with moderate to severe depression³

• As an add-on therapy for patients with moderate to severe depression who have not responded to 6-8 weeks of antidepressant treatment⁴

• To reduce the risk of relapse in patients treated with antidepressants who have residual symptoms or are considered to be at significant risk of relapse³

For those with mild to moderate depression, we should emphasise that CBT and antidepressant treatment are only comparable if antidepressants

are continued for at least 6-9 months after recovery.1 Choice may also be influenced by patients’ reluctance

to commit to CBT, limited availability of high-intensity psychotherapy and delays in accessing treatment.

It can be argued that case management is a more cost-effective way of reducing relapse rates and we may wish to limit CBT to those who

do not respond to antidepressant treatment, those who relapse on treatment and those with residual symptoms and impaired functioning after 3-4 months’ treatment.

Dr Phillip Bland