The review question was clear and supported by inclusion criteria that appeared to be sufficiently detailed to enable replication. The search strategy included some relevant sources, but the restriction to published English language articles meant that language and publication biases could not be ruled out; it is possible that relevant studies were missed. The reporting of the review process was patchy, with only the procedure for data extraction demonstrating any attempt to minimise reviewer error and bias.
There was no reported assessment of trial quality, which represented a threat to the reliability of review findings. Trial details were presented, but there was little detail on patient characteristics, making it difficult to interpret the generalisability of findings. The method of synthesis was appropriate, according to the presence of heterogeneity.
The authors' conclusion largely reflected the evidence presented, but the extent to which this is reliable is unclear.