[Meta-analysis: a structured bibliographic protocol]

Meta-analysis is a way of reviewing literature in a structured and systematic format. A formalized protocol for selection of the reviewed papers and a qualitative as well as quantitative evaluation are essential. Mathematical pooling of the results of the individual studies can be part of the process. A number of pitfalls are possible. However, when performed in a correct way and evaluated critically by the reader, a meta-analysis can add consistently to the medical knowledge concerning a specific subject.