The authors stated their inclusion criteria clearly. They listed the electronic databases and other sources searched, including the search terms used, but omitted to state the search dates. The search was limited to two electronic databases, although the authors attempted to identify unpublished literature by contacting researchers known to be working in the area. One unpublished study was found but was excluded from the ES analysis. This narrow search strategy may have missed relevant studies, allowing the introduction of selection bias. Publication bias was not assessed.
The validity of the individual studies did not appear to have been formally assessed, although the methodological strengths and shortcomings of the studies were discussed. The authors did not report details relating to the decision-making process for selecting the studies and extracting the data; e.g. how many of the reviewers were involved, whether the studies were examined independently, whether the reviewers were blinded to the source, and how any disagreements were resolved.
Adequate details of the studies were reported in tabular format, and were supplemented with narrative descriptions. However, there were weaknesses in the study synthesis. Whilst a statistically significant advantage in CBT-RC over ST-RC was seen in the between-group ES comparison, the ESs of different primary outcomes were pooled together. The ES estimates for both the positive and negative symptoms were calculated and presented in tabular format, but were not examined for statistical significance.
The authors' conclusions should be interpreted with caution owing to the limitations of the search strategy, the lack of details relating to the review process, and the weakness in the synthesis of the studies.