Reporting guideline for overviews of reviews of healthcare interventions: The Preferred Reporting Items for Overviews of Reviews (PRIOR) Explanation & Elaboration

The Preferred Reporting Items for Overviews of Reviews (PRIOR) statement provides an evidence-based reporting guideline developed using established, rigorous methods that involved a four-stage process (project launch, evidence reviews, modified Delphi exercise, development of the reporting guideline) and an international stakeholder group representing varied experiences (e.g., authors, peer reviewers, editors, readers) and roles (e.g., patients/public, researchers, statisticians, librarians, healthcare professionals, policymakers).The PRIOR statement includes: a checklist with 27 main items that cover all steps and considerations involved in planning and conducting an overview of reviews of healthcare interventions; an explanation and elaboration document with rationale, essential elements, additional elements, and example for each item; and a flow diagram.The methods and results of the PRIOR guideline development, including the checklist and flow diagram, are reported separately. This document contains the explanation and elaboration for each checklist item.