This review addressed a clear research question. The inclusion and exclusion criteria were brief, which may hinder the reproduction of the study. Limited sources were searched and there were no specific attempts to locate unpublished studies, which introduced the potential for publication bias. The authors did not state how many reviewers were involved in the methodology, which may introduce bias and error. The validity was not assessed and the quality of the studies is unknown. A narrative synthesis was appropriate given the small number of studies and the heterogeneity between included studies. The methods of this review were weak and, given the paucity of studies, the small samples, different study designs, and lack of standardisation of outcomes, there were no definitive conclusions.
Overall, the authors' conclusions reflected the evidence presented. These conclusions should be treated with caution because of the weak methodology and lack of studies.