Guidance for overviews of reviews continues to accumulate, but important challenges remain: A scoping review update

Article type
Authors
Gates M1, Gates A1, Guitard S1, Pollock M2, Hartling L1
1Alberta Research Centre for Health Evidence, Department of Pediatrics, University of Alberta
2Institute of Health Economics
Abstract
Background. Overviews of reviews (overviews) provide an invaluable resource for clinical decision-makers by combining large volumes of systematic review (SR) data into a single synthesis. The production of high-quality overviews hinges on the availability of practical evidence-based guidance for conduct and reporting.

Objectives. Within the broad purpose of informing the development of a reporting guideline for overviews, we aimed to provide an up-to-date map of existing guidance related to the conduct of overviews, and to identify common challenges that authors face when undertaking overviews.

Methods. We updated our previous scoping review (published 2016) using the search methods that had produced the highest yield: ongoing reference tracking (retrospectively from 2014 to present in Pubmed, Scopus, and Google Scholar), handsearching conference proceedings and websites, and contacting authors of published overviews. Using a qualitative meta-summary approach, one reviewer extracted, organized, and summarized the guidance and challenges presented within the included documents. A second reviewer verified the data and synthesis.

Results. We located 22 new guidance documents, for a total 74 documents produced by 30 research groups. The newly available guidance helps to resolve some existing challenges in the production of overviews. Important developments include the availability of a decision tool for selecting SRs for inclusion in overviews (e.g., in the event of overlapping and/or discordant SRs) and strengthened guidance on handling primary study overlap at the analysis stage. Despite marked progress, several areas continue to be hampered by inconsistent or lacking guidance. For example, there is ongoing debate about whether, when, and how supplemental primary studies should be included in overviews. Consensus is lacking on the preferred tool for assessing risk of bias or methodological quality of included SRs, and how these tools might best be applied in overviews. Guidance remains scant on how to extract and use appraisals of quality of the primary studies within the included SRs and how to adapt GRADE methodology to overviews. The challenges that overview authors face are often related to the above-described steps in the process where evidence-based guidance is lacking or conflicting.

Conclusion. The rising popularity of overviews has been accompanied by a steady accumulation of new, and sometimes conflicting, guidance. While recent guidance has helped to address some of the challenges that overview authors face, areas of uncertainty remain. These findings are being used to inform the development of a reporting guideline for overviews, which aims to support the high quality and clarity of reporting that is needed to substantiate overviews as a robust source of evidence for healthcare decision making.

Patient or consumer involvement. Patients and consumers were not directly involved, but are expected to benefit from the improved conduct and reporting of overviews that is supported by this scoping review.