The review addressed a focused question supported by clearly defined inclusion criteria. The literature search was adequate for published studies. No specific attempts were made to locate unpublished studies and the review was restricted to English-language studies and so there was a possibility of language and publication bias. Details of the review process were not reported and so it was not possible to determine whether appropriate steps were taken to minimise bias and errors. Study quality was not formally assessed and so the reliability of the included studies was unclear. Details of the included studies were summarised in tables and discussed in the text, which helped to determine the generalisability of findings. A narrative synthesis was presented. It may have been more informative to have conducted a more statistical synthesis, and possibly a meta-analysis for studies that reported outcomes using the NPI.
The authors' cautious conclusions reflected the evidence, but should be interpreted with caution due to the possibility of missed studies, lack of details on study quality and limitations in the synthesis.