The review question was supported by broad inclusion criteria, particularly in terms of study design and outcome. Several sources were searched for relevant studies, non-published literature was sought and non-English articles were included, reducing the possibility of language and publication bias. Methodological methods used to select studies for inclusion and extract data were likely to minimise the possibility of reviewer error and bias.
The authors did not appear to have assessed study quality, limiting any interpretation of the results. The decision to combine studies in a meta-analysis appeared appropriate and statistical heterogeneity was assessed.
It should be noted that one of the review authors made the financial disclosure that he is or was a research consultant for Sinexsus, Inc.
Whilst the authors' conclusion is a reasonable interpretation of the evidence presented, caution should be exercised given the paucity of available data and unclear study quality.