Background Decisions about the design and reporting of randomized trials and systematic reviews should be informed by the best available methodological research. Ideally this evidence should be summarised in systematic reviews. This overview includes systematic methodology reviews relevant to conducting and reporting pragmatic randomized controlled trials (RCTs) and systematic reviews of RCTs. It was undertaken as part of Practihc (Pragmatic Randomized Controlled Trials in HealthCare) and in collaboration with ESCORT.

This overview of reviews aims to support Practihc guidance for designing pragmatic randomised trials:

• to inform future revisions of the CONSORT guidelines for reporting randomised trials
• to inform guidelines for conducting and reporting systematic reviews
• and to inform decisions about priorities for Cochrane methodology reviews

Methods Methodology reviews were compiled by searching the Cochrane Methodology Register, the Cochrane Database of Methodology Reviews, and UK NHS HTA Methodology Reviews. Two reviewers identified potentially relevant reviews. These were retrieved and the same two reviewers assessed the relevance.

Main results A total of twenty-eight methodology reviews were included covering sixteen topic areas. Thirty-one structured abstracts were prepared for the included reviews and a commentary was written for each topic area.

Conclusions There are relatively few systematic methodology reviews and many of the included methodology reviews found a paucity of empirical evidence. As a consequence, many decisions about the design and reporting of randomized trials and systematic reviews must be based on logical arguments, often with uncertainty about what empirical evidence is available, due to the lack of a systematic methodology review, or uncertainty about the impact of alternative decisions, due to the lack of empirical evidence.

This uncertainty not only impacts on the use of resources for research, but it has important consequences for the availability of reliable evidence to inform decisions about health care.