The review addressed a tightly defined research question with appropriate inclusion criteria. The search was limited to a single database plus reference checking, so potentially eligible trials may have been missed. The review processes were only partially described, which made it difficult to rule out reviewer error/bias.
No quality assessment was reported, so the reliability of each primary trial was unclear. Although only limited trial details were presented, additional information presented in the discussion suggested that the trials were clinically very varied (questions were raised over the method of administration for one trial). The synthesis appeared appropriate to the data available.
While the authors' conclusion reflects the results of the meta-analysis, the variation between the trials and their various potential flaws suggest that the evidence base is insufficient to support claims of efficacy or ineffectiveness.