There are a number of studies that show the positive impact that cognitive behavioural therapy can have on the symptoms of obsessive-compulsive disorder (OCD). This randomised controlled trial conducted by researchers in Denmark sought to shed some light on the effectiveness of group cognitive behavioural therapy compared to individual CBT.

110 outpatients with OCD were randomised to either:

• 15 sessions of group CBT
• 15 sessions of individual CBT

Outcomes were measured before and after treatment, as well as at follow-up (6 months and 12 months).

The researchers also conducted a meta-analysis of 4 comparative studies in this field, including this randomised controlled trial.

The results showed:

• Group CBT and individual CBT both saw large and stable pre-post effect sizes (d = 1.06-1.24 on the Yale-Brown Obsessive Compulsive Scale)
• There were no significant between-group differences in outcome at any data point (ds= -0.13 to 0.15)
• The meta-analysis found a between-group mean effect size of (d= 0.15 favouring individual over group CBT at post-treatment (95% confidence interval, -0.12, 0.42).

The authors concluded:

The results of this study suggest that OCD can be treated effectively with a group format of CBT, thus sparing some therapist resources, although the four accomplished comparative studies do not rule out the possibility of a small superiority of individually conducted CBT.

Jónsson H, Hougaard E, Bennedsen BE. Randomized comparative study of group versus individual cognitive behavioural therapy for obsessive compulsive disorder. Acta Psychiatr Scand. 2011 May;123(5):387-97. doi: 10.1111/j.1600-0447.2010.01613.x. Epub 2010 Oct 12. [PubMed abstract]