Quality control in systematic reviews and meta-analyses.

Systematic reviews and meta-analyses are being submitted to, and being published by biomedical journals with increasing frequency. In order to maintain the utility of such publications and avoid misguidance it is important that these studies are conducted to a high standard. This article aims to provide guidance both for those researchers undertaking and reporting such studies and for the readers of such articles. Details of a suggested method for conducting a systematic review are given, including methods for literature searches, data abstraction and data extraction followed by a brief overview of common methods used for meta-analyses and the interpretation of the results of meta-analysis.