The review addressed a focused question supported by clearly defined inclusion criteria. The literature search was adequate for published studies, but restriction of the review to studies published in certain languages raised the possibility of language and publication bias. This was assessed in the review, but methods used were not appropriate for diagnostic accuracy studies. Appropriate steps were taken to minimise bias and errors at all stages of the review process.
Study quality was not formally assessed, so the reliability of the included studies was unclear. Details on individual studies were also lacking. Methods used to pool studies appeared appropriate and results were clearly presented using graphical displays.
The authors' conclusions are supported by the data, but should be interpreted with caution given the possibility of missed studies and lack of a formal quality assessment.