Long-term effectiveness and cost-effectiveness of cognitive behavioural therapy as an adjunct to pharmacotherapy for treatment-resistant depression in primary care: follow-up of the CoBalT randomised controlled trial

RCT (n=469) found that CBT as an adjunct to usual care that includes antidepressants is clinically effective (mean BDI-II score 19.2 vs. 23.4 usual care; p<0.001) and cost effective over the long-term for individuals whose depression has not responded to pharmacotherapy.

The study reported that the average annual cost of trial CBT per participant was £343 and incremental cost-effectiveness ratio was £5374 per QALY gain which represented a 92% probability of being cost effective at the NICE QALY threshold of £20 000.

A commentary notes that notwithstanding the positive results, this trial is also a reminder that even a combination of antidepressants and individual CBT does not provide a complete solution for major depressive disorder. Years after receiving individual CBT and continued antidepressants, the average CoBalT participant still scored 19 points on the Beck Depression Inventory, which puts them into the moderately depressed range. It adds that although data for functional outcomes such as employment are missing, these symptoms probably continue to seriously affect quality of life and productivity. Therefore, strategies to increase the efficacy of the existing treatments and on developing more effective treatments for major depressive disorder are needed.