Randomised controlled non-inferiority trial with 3-year follow-up of internet-delivered versus face-to-face group cognitive behavioural therapy for depression

Background: Guided internet-delivered cognitive behaviour therapy (ICBT) has been found to be effective in the treatment of mild to moderate depression, but there have been no direct comparisons with the more established group-based CBT with a long-term follow-up.

Method: Participants with mild to moderate depression were recruited from the general population and randomized to either guided ICBT (n=33) or to live group treatment (n=36). Measures were completed before and after the intervention to assess depression, anxiety, and quality of life. Follow-ups were conducted at one-year and three-year after the treatment had ended.

Results: Data were analysed on an intention-to-treat basis using linear mixed-effects regression analysis. Results on the self-rated version of the Montgomery-Åsberg Depression Scale showed significant improvements in both groups across time indicating non-inferiority of guided ICBT, and there was even a tendency for the guided ICBT group to be superior to group-based CBT at three year follow-up. Within-group effect sizes for the ICBT condition at post-treatment showed a Cohen's d=1.46, with a similar large effect at 3-year follow-up, d=1.78. For the group CBT the corresponding within-group effects were d=0.99 and d=1.34, respectively.

Limitations: The study was small with two active treatments and there was no placebo or credible control condition.

Conclusions: Guided ICBT is at least as effective as group-based CBT and long-term effects can be sustained up to 3 years after treatment.