10. Meta‐analysis: Part 2: assessing the quality of published meta‐analyses

I n Part 1 of this review we concluded that metaanalysis has supplemented , and may eventually replace, the traditional narrative review as the prin. cipal source of information for those wishing to obtain an overview of new developments regarding the aetiology or management of the diseases encompassed by their clinical practice. ' We reviewed the aims of meta-analysis and evidence that it is a val id and reliable technique. However, this conclusion is itself only valid if steps have been taken by authors to minimise a range of biases which can affect meta-analyses. In Part 2 of this review we provide guidelines for assessing the quality of published meta-analyses. As in Part 1 we have illustrated important points with examples from the literature. In compiling Part 2 we have drawn on the work of Light and Pillemer, Sacks et al. and Oxman and Guyatt. ··· All have provided excellent reviews of meta-analysis which should be consulted by those interested in expanding their knowledge of this important topic. Meta-analysis is a discipline which provides methods for finding , appraising and combining data from a range of studies. Bias can intrude at each of these stages. Bias can also intrude during a traditional narrative review, but