Key points:

• The conduct Standards should be consulted during preparation of the protocol for a Cochrane Intervention Review.
• They describe the methods that should be implemented throughout the review process.
• Few specific methods are mandatory, one notable exception being the Cochrane tool for assessing risk of bias when randomized trials are included in the review.

The MECIR Standards for conduct of a Cochrane Intervention Review provide expectations for the general methodological approach to be followed from designing the review up to interpreting the findings at the end. They should be consulted particularly when preparing the protocol for the review. The protocol describes the review question, the criteria for considering studies for the review, and the methods that will be followed to identify, appraise, summarize and synthesize the studies. Cochrane led the way in making protocols available to readers of the Cochrane Library. They ensure transparency in how reviews are prepared and allow the planned methods to be critiqued. Specification of the review question (through setting the review’s objectives) and the criteria for including studies are critical to the success of the review and the first two sections of the Standards address these tasks. The following section addresses selection of the outcomes of interest, an important aspect that should be prespecified carefully to avoid the need for post hoc decisions that could be influenced by the data.

The remaining Standards address the detailed methodology that will be followed during the review, covering the search for studies, selection of studies into the review, data collection, risk of bias assessment, synthesis (including any meta-analysis approaches), and overall assessment of the evidence. With few exceptions (such as use of the Cochrane Risk of Bias 2 tool for randomized trials), the precise methods to be used are not prescribed, For example, authors are free to use any meta-analysis method, although there is a potential convenience to both authors and readers if those implemented in Review Manager (RevMan) software are used. 

Julian Higgins
Professor of Evidence Synthesis
University of Bristol