Transdiagnostic versus diagnosis specific cognitive behavioural therapies for anxiety: A meta-analysis

- Equivalence of treatment effects of transdiagnostic and diagnosis-specific CBT remain unclear.
- Data from 80 treatment studies examined using meta-analysis.
- Results suggest equivalence of transdiagnostic and diagnosis-specific CBT outcomes.
- Increased rates of comorbidity were unrelated to outcomes in transdiagnostic CBT, but attenuated outcomes in diagnosis-specific CBT.

Research evaluating transdiagnostic CBT (tCBT) demonstrates its efficacy. Some evidence suggests equivalence between tCBT and diagnosis-specific CBT (dxCBT), however more investigations are necessary to clarify any difference in efficacy. This meta-analysis was conducted to compare tCBT and dxCBT, and to investigate the differential impact of comorbidity on effect sizes. Pre and post scores from primary anxiety measures in 83 treatment conditions, taken from studies primarily targeting anxiety disorders, were summarised and compared. Meta-regression analyses were then used to test the effects of comorbidity. DxCBT and tCBT meta-effects were found to be large, where g = 0.951, 95% CI: 0.874-1.027, and g = 1.059, 95% CI: 0.876-1.242, respectively. While statistically different (p = 0.008), overlap of confidence intervals indicated a lack of clinical significance. Furthermore, no relationship between comorbidity rate and tCBT outcome was observed. These results were discussed in the context of previous findings in the transdiagnostic CBT literature.