The new Chapter 21 provides authors with important guidance for conducting a living systematic review including what defines a living systematic review, when this approach is appropriate, and specific methodological guidance.
The publication of the new chapter is accompanied by substantial updates on behalf of the Prospective Meta-Analysis Methods Group to Chapter 22, which focuses on prospective and collaborative approaches to evidence synthesis.
What’s changing?
The original chapter, 'Prospective approaches to accumulating evidence', has been divided into two chapters. Chapter 21 now focuses exclusively on living systematic reviews, while Chapter 22 has been updated and retitled 'Prospective, collaborative approaches to meta-analysis'.
Chapter 22: Prospective, collaborative approaches to meta-analysis
The revised Chapter 22 describes a range of prospective approaches, including fully prospective meta-analysis (PMA); nested (or partially prospective) PMA; the framework for prospective, adaptive meta-analysis of aggregate data (FAME); Anytime Live and Leading INterim meta-analysis (ALL-IN); and collaborative network trials. The chapter also discusses how PMA methods may be adapted depending on whether the goal is collation of individual participant data or aggregate-level data.
New content covers applications in health emergencies (e.g. COVID-19), incorporation of non-randomized studies, embedding methodological studies within a review and PMA, and emerging opportunities such as artificial intelligence.
Chapter 21: Living systematic reviews
Although Cochrane has provided some guidance on living systematic reviews previously, the new Chapter 21 brings together current methodological best practice for conducting living systematic reviews into a single resource. It will cover what defines a living systematic review, when this approach is appropriate, and specific methodological guidance.
"The pace of health research has accelerated in recent years. Living systematic reviews have emerged as an important way to ensure that evidence remains current and useful for decision-makers.
By introducing a dedicated chapter to the Handbook, we are bringing together methodological guidance in one authoritative resource and helping review teams deliver living evidence that is rigorous, transparent, and trustworthy." – Rupa Sarkar, Cochrane’s Editor in Chief
The new chapter will replace the current Chapter 21, which covers qualitative evidence synthesis (QES) methods. Since the publication of the dedicated Cochrane-Campbell Handbook for Qualitative Evidence Synthesis, guidance on QES methods is now available in a standalone resource.
Why it matters
Living systematic reviews and prospective, collaborative meta-analysis approaches are helping evidence synthesis evolve to meet increasingly complex research challenges.
Prospective and collaborative approaches can address some important limitations of conventional retrospective meta-analysis. In particular, identifying studies and agreeing methods before results are known can reduce subjectivity and the potential for bias.
Working together can ensure more complete, consistent and detailed data for meta-analysis. In addition, collaboration and prospective planning can create opportunities for earlier engagement with guideline developers and policymakers, helping ensure evidence is translated.
Living systematic reviews have become increasingly important as the volume and pace of health research continues to grow. Interest in living systematic reviews grew significantly during the COVID-19 pandemic, when the need for up-to-date evidence highlighted their value. Unlike traditional reviews, which are updated periodically, living systematic reviews are maintained through ongoing surveillance and incorporation of new evidence. This approach can help researchers, healthcare professionals, policymakers and patients have access to the most current and reliable evidence when making decisions.
How this will help authors
The new Chapter 21 aims to improve the consistency and methodological rigour of future living systematic reviews by bringing together current best practice in a single resource. It will help authors determine when a living review is appropriate and clarify best practices to improve the reliability across living systematic reviews.
While many aspects of prospective meta-analyses are similar to standard Cochrane reviews, they often require different workflows and closer collaboration with study investigators. The updated Chapter 22 guides authors through the key stages of designing, planning, conducting, reporting and disseminating prospective, collaborative meta-analyses.
Together, these updates aim to make both living reviews and prospective collaborative meta-analysis methods more accessible to review authors and support the production of high-quality, timely and trustworthy evidence.
Supporting the future of living evidence
This work is part of Cochrane’s wider strategy to make sure trusted evidence is relevant, timely and accessible for those who need it. For example, as part of our efforts to make our evidence more usable by investing in structured, living, open, and interoperable data we are exploring how living reviews may publish their dataset more frequently. We hope to share more information about this work in due course.
