The review question was supported by inclusion criteria for participants, intervention, outcomes and study design. Four relevant databases were searched for studies in all languages, reducing the possibility of language bias. However, only published studies were included, increasing the risk of publication bias. The author acknowledged the difficulty of locating all studies in the field of complementary medicine.
Data extraction and validity assessment were performed in duplicate, reducing the risk of error and bias, but this was not reported for study selection. Trial quality was assessed using a published tool and was taken into consideration in the results. Narrative synthesis appeared appropriate given the variety of comparators used.
The author's conclusion reflected the evidence presented, but its reliability is unclear given the possibility of publication bias.