The review question and inclusion criteria were generally clear. The search appeared adequate, although the databases searched were not explicitly reported. The review was limited to English language publications, so there could be a risk of language bias. It was unclear whether any efforts were made to locate unpublished studies, so the risk of publication bias was uncertain. Study selection was performed by two reviewers, minimising risk of reviewer errors or bias affecting the review.
Quality of the included studies was not formally assessed, so the reliability of these studies and the synthesis based on them is uncertain. Adequate details of included studies were reported. Standard methods were used to pool RCTs reporting the primary outcome, but only three small trials were included. Statistical heterogeneity was not significant, but there were considerable differences between the interventions used, which suggested that meta-analysis may not have been appropriate. Planned sensitivity and subgroup analyses were limited by the small number of included studies. The authors noted various limitations of the review, including a potential lack of generalisability.
The authors' conclusions are in line with the evidence presented, but limitations in the evidence base and the review process suggest that the conclusions should be interpreted with caution.