The review question was clearly stated and inclusion criteria were appropriately defined. Several relevant sources were searched. Attempts were made to minimise publication bias, but it was not clear if attempts were made to minimise language bias. The potential for publication bias was assessed, but the small number of trials limited the usefulness of the funnel plot. Methods were used to minimise reviewer errors and bias in the extraction of data, but it was not clear whether similar steps were taken in study selection and validity assessment.
Although study validity was assessed, results of the assessment were not reported, which made it difficult to judge the likely reliability of the results. Appropriate methods were used for the meta-analyses; heterogeneity was assessed. Some limitations of the review were discussed including low event rates and the absence of long-term data.
The authors’ conclusions reflected the evidence presented, but incomplete reporting of review methods and lack of reporting of trial validity make it difficult to assess their reliability.