Supplementary Material for: Efficacy of Cognitive Behaviour Therapy versus Anxiety Management for Body Dysmorphic Disorder: A Randomised Controlled Trial

Background: The evidence base for the efficacy of cognitive behaviour therapy (CBT) for treating body dysmorphic disorder (BDD) is weak. Aims: To determine whether CBT is more effective than anxiety management (AM) in an outpatient setting. Method: This was a single-blind stratified parallel-group randomised controlled trial. The primary endpoint was at 12 weeks, and the Yale-Brown Obsessive Compulsive Scale for BDD (BDD-YBOCS) was the primary outcome measure. Secondary measures for BDD included the Brown Assessment of Beliefs Scale (BABS), the Appearance Anxiety Inventory (AAI) and the Body Image Quality of Life Inventory (BIQLI). The outcome measures were collected at baseline and week 12. The CBT group, unlike the AM group, had 4 further weekly sessions that were analysed for their added value. Both groups then completed measures at their 1-month follow-up. Forty-six participants with a DSM-IV diagnosis of BDD, including those with delusional BDD, were randomly allocated to either CBT or AM. Results: At 12 weeks, CBT was found to be significantly superior to AM on the BDD-YBOCS [β = -7.19; SE (β) = 2.61; p < 0.01; 95% CI = -12.31 to -2.07; d = 0.99] as well as the secondary outcome measures of the BABS, AAI and BIQLI. Further benefits occurred by week 16 within the CBT group. There were no differences in outcome for those with delusional BDD or depression. Conclusions: CBT is an effective intervention for people with BDD even with delusional beliefs or depression and is more effective than AM over 12 weeks.