Study-based registers of randomized controlled trials: Starting a systematic review with data extraction or meta-analysis.

Introduction: Despite years of use of study-based registers for storing reports of randomized controlled trials (RCTs), the methodology used in developing such registers/databases has not been documented. Such registers are integral to the process of scientific reviewing. We document and discuss methodological aspects of the development and use of study-based registers. Although the content is focused on the study-based register of randomized/controlled clinical trials, this work applies to developers of databases of all sorts of studies related to the human, animals, cells, genes, and molecules. Methods: We describe necessity, rationale, and steps for the development, utilization and maintenance of study-based registers as well as the challenges and gains for the organizations supporting systematic reviews of the published and unpublished literature. Conclusion: The ultimate goal of having a study-based register is to facilitate efficient production of systematic reviews providing rapid, yet accurate, evidence for the decision-makers. We argue that moving towards study-based registers is an inevitable welcome direction and that infrastructures are ready for such movement.