Basic reporting

Overall, this is a very well written article.

Relevant prior literature is appropriately described and referenced and the case for this study is well made. The structure of the article is clear, clean, and concise.

The authors should review the sentence beginning on line 10, p15, which would benefit from editing.

Experimental design

This paper represents original primary research, the research question is well defined, and the study reflects a high technical standard.

The sample size calculations were appropriate to address the overall comparison between treatment and control, but were not adequate for the subgroup analyses. This limitation should be acknowledged in the Discussion. Moreover, it is conceptually problematic to include fear disorders (panic/social anxiety) with worry disorders (GAD), and this may have further confounded subgroup analyses. Again, this should be acknowledged in the Discussion.

Validity of the findings

The data appear robust and statistically sound. The exclusion of participants with low or high scores helped restrict standard deviation, which increased within group effect sizes, but the authors appropriately focused on between-group effect sizes as indicators of difference due to treatment.

The control group appeared to receive a non impotent intervention, which increases confidence that the treatment intervention was efficacious.

The conclusion that the manual used in the study represented a 'solid implementation' of a psychodynamic therapy based on the affect-phobia model (pg 17, line 17) is difficult to evaluate. I suggest the authors be more circumspect about this position.

Comments for the author

The components of the treatment appear common to evidence-based principles of recovery from anxiety/depression. I encourage the authors to consider this issue in the Discussion.