CRD Summary: The review concluded that there was evidence of efficacy for treatment of quetiapine for acute mania in bipolar disorder, but that the robustness of the evidence was questionable. The authors' conclusions were an accurate reflection of the results of the review, but it should be borne in mind that the review was based on a small number of studies.

[The included studies evaluated quetiapine as monotherapy. Some studies compared quetiapine with another pharmacological agent, such as lithium and haloperidol, or placebo. Other studies compared quetiapine as adjunct therapy augmenting lithium or divalproex compared to placebo augmenting lithium and divalproex.]

CRD Commentary: The inclusion criteria were clear for intervention, study design and outcomes, but were not explicitly defined in terms of participants. Several relevant sources were searched and some attempts were made to locate unpublished studies, thus limiting the possibility of publication bias. It was not clear whether any language limitations had been applied and so the potential for language bias could not be assessed. Methods used to select studies and extract data were not described and so it was not known whether efforts were made to reduce reviewer errors and bias. Only RCTs were included, but their quality was not assessed further and so results from these studies and any synthesis may not be reliable. Some characteristics of the included studies were presented in tables, but details of participants were not reported either in the text or the tables, therefore, it was not possible to assess the generalisability of the results. A narrative synthesis was appropriate given the differences between studies. Although the main outcome was a reduction in Young Mania Rating Scale scores, the ages of participants were not reported for all the studies, however, results appeared to be reported for both adults and adolescents. The authors appropriately discussed the limitations of the included studies and reported discrepancies between published data and web-based data. The authors' cautious conclusion was an accurate reflection of the results of the review, but it should be borne in mind that the review was based on a small number of studies.