Internet-based cognitive behaviour therapy for perfectionism: secondary impacts and modes of delivery

It has been suggested that guided internet CBT for perfectionism (ICBT-P) can substantially decrease perfectionism in low doses (3 or less modules) but appears to only impact secondary outcomes with higher doses of treatment. The current study addressed this question, as well as the best method to promote higher dosage use. Two sequential randomized ICBT-P studies were conducted with participants who self-identified as having difficulties with perfectionism. The first study randomized participants (N=51) to receive either a 3-module ICBT-P or a wait-list comparison. The second study (N=55) randomized participants to a fixed format (asked to complete all 8 modules at a rate of 2 a week over a 4-week period) or a flexible format (after completing the first psychoeducational module, they decided how many and in what order they completed the 8 modules over the 4-week period). We examined impact on our primary variables, perfectionistic concerns and standards, and negative affect, body image flexibility, and self-efficacy. On average, within-group effect size improvements were double for those participants doing the 8- versus 3-module intervention, with double the modules completed. The shorter intervention impacted perfectionism but not the secondary variables, whereas the longer intervention impacted all outcomes except for self-efficacy. There was no difference in the number of modules completed or impact of the fixed versus flexible formats.