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For some kind of comparison of effect sizes in CBT, I point readers to
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3263389/
Cognitive behavioural therapy in anxiety disorders: current state of the evidence.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3263389/
Cognitive behavioural therapy in anxiety disorders: current state of the evidence.
Five studies examined the efficacy of CBT in panic disorder in a randomized placebo-controlled design.6 The effect size was 0.35 (95% CI 0.04-0.65), indicating a small to medium effect ((Figure 1).How important it is to take into account the type of effect size when appraising the magnitude of effect can be seen from a different meta-analysis that calculated uncontrolled pre- to post-treatment effect sizes.9. That meta-analysis reported an effect size of 1.53 for CBT in panic disorder.
Efficacy
The controlled effect size for CBT in generalized anxiety disorder was 0.51 (95% CI 0.05-0.97), indicating a medium effect (Figure 1) although only two studies using a randomized controlled design to examine CBT treatment in patients with generalized anxiety disorder were available. Nevertheless, these results were recently corroborated by a Cochrane meta-analysis examining psychological treatments of generalized anxiety disorder.14 Based on thirteen studies, the authors concluded that psychological therapies, all using a CBT approach, were more effective than treatment as usual or wait list control in achieving clinical response at post-treatment (RR 0.64, 95% CI 0.55-0.74). However, those studies examining CBT against supportive therapy (nondirective therapy and attention-placebo conditions) did not find a significant difference in clinical response between CBT and supportive therapy at post-treatment (RR 0.86, 95%CI 0.70 to 1.06).
Again, the meta-analysis calculating uncontrolled pre- to post-treatment effect sizes found much a larger overall effect size of 1.80. 9
Efficacy
In seven randomized placebo-controlled treatment studies, the effect of CBT in social anxiety disorder was 0.62 (95% CI 0.39-0.86, Figure 1) indicating a medium effect. In a separate meta-analysis, the uncontrolled pre- to post-treatment acute treatment effect size was 1.27.9
Effectiveness
In eleven effectiveness studies, the uncontrolled pre- to post-treatment effect size was 1.04 (95% 0.79-1.29).5
Efficacy
In six randomized placebo-controlled efficacy trials of CBT in PTSD, the controlled effect size was 0.62 (95% CI 0.28-0.96), indicating a medium effect. A recent Cochrane analysis of psychological treatment in PTSD15 supported these findings and found that trauma-focused CBT was more effective than treatment as usual or wait list control. The uncontrolled effect size derived from a separate meta-analysis was 1.86. 9
Effectiveness
Six studies examined the effectiveness of CBT in the treatment of PTSD5 and found an uncontrolled pre- to post-treatment effect size of 2.59 (95% CI 2.06-3.13).
Not surprisingly therefore, in the meta-analysis of randomized, placebo-controlled trials, pooled analyses using data from ITT samples yielded much smaller effect sizes than those derived from completer samples. In the completer sample, the overall Hedges' g for anxiety disorder severity was 0.73 (95% CI: 0.56-0.90 and the pooled odds ratio for treatment response was 4.06 (95% CI: 2.78-5.92). However, in ITT analyses that were only provided for the minority of included studies, the Hedges' g for anxiety disorder severity was 0.33 (95% CI: 0.110.54), and the odds ratio for treatment response was 1.84 (95% CI: 1.17-2.91). The authors of the meta-analysis6 concluded the following:
Given the status of CBT as the gold-standard psychosocial intervention for treating anxiety disorders, it is very surprising and concerning that after more than 20 years of CBT treatment research, we were only able to identify 6 high-quality randomized placebo controlled CBT trials that provided ITT analyses for continuous measures and only 8 trials for ITT response rate analyses. In our opinion, this is an unacceptable situation that will have to change for psychosocial intervention to become a viable alternative to pharmacotherapy in the medical community.