CRD Summary: This review concluded that tirilazad had no effect on clinical outcome after subarachnoid haemorrhage, but did decrease symptomatic vasospasm in five trials. Poor reporting of the review process means that the reliability of the authors' conclusions cannot be determined.

CRD Commentary: The research question was supported by inclusion criteria for participants, intervention and study design, but these were not clearly stated. The searches were not well described but appeared to be limited. It was not clear whether any language restrictions were imposed or whether the searches were restricted to published studies, so publication and language biases could not be ruled out. The authors did appear to have assessed validity but the criteria were not described. The review process was not described, so it was not known whether reviewer error and bias was a possibility. Meta-analysis appeared to be appropriate and heterogeneity was examined. Poor reporting of the review process means that the reliability of the authors' conclusions cannot be determined.