The review question was clear, and the inclusion criteria were sufficiently specified to allow replication. Various data sources were searched, and attempts were made to locate unpublished data. The review process was not reported, making it difficult to determine whether steps were taken to minimise error and bias. The absence of a formal quality assessment means that the reliability of the included trials is unclear.
Trial details were presented and statistical heterogeneity was not significant, even though clinical heterogeneity was evident. Based on the statistical heterogeneity, the method of synthesis was appropriate. Most of the trials did not include NPI as a primary outcome, and the samples were small in two of the trials, which could reduce the reliability of the findings. Some of the authors' conclusions (in relation to the superiority of other drugs) were not substantiated by the placebo-controlled trials in this review.
The authors' conclusion reflects the evidence presented, but method limitations make the reliability of this conclusion unclear.