[Value of the Cochrane Collaboration: the point of view of meta-analysis practitioner]

To-date, most of the meta-analyses performed are exclusively based on published data; however, some are based on individual patient data of published and unpublished trials. This last method is the reference method, but it is time-consuming and costly. The quality of meta-analyses is varied and could partly explain the criticisms this method is subject to. The Cochrane Collaboration could help in the following fields: promotion of registries of trials and meta-analyses, methodological research on meta-analysis, improvement of trial search, trial data storage and pertinence of information in published trials, improvement of meta-analysis quality, and dissemination of results. The interventions of the Cochrane Collaboration could thus improve the quality and the time performance of meta-analyses, reducing expenses and enabling the widespread dissemination of regularly updated results.