The review question and supporting inclusion criteria were clearly stated. A satisfactory search of the literature was undertaken, with attempts to locate both published and unpublished data. All of the included studies were RCTs, but their quality was not assessed. The author did not state how many reviewers were involved in each stage of the review process, which means that reviewer error and bias cannot be ruled out.
The patient characteristics were not reported, making it unclear how comparable patients were across trials. Samples were small, there were considerable differences in the trial methods, and the outcomes were subjective and open to bias. The treatments were short term. It was unclear if the methods used to combine and impute the data were appropriate, and what effect they might have had on the overall estimates of effect. The forest plots displayed very wide confidence intervals for some trials, which indicates imprecision.
There were substantial limitations to the review, and there was little evidence, which was varied. Given these limitations, the treatment effect may have been overestimated. The author's conclusions cannot, therefore, be considered to be reliable.
Conflict of Interests: The author was an employee of Abbott, a manufacturer of betahistine.