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1.1 Introduction

Owned by Carolyn Phillips
Last updated: Mar 27, 2024
4 min read

Evidence syntheses (systematic and scoping reviews) do not exist in isolation, and it is increasingly acknowledged that they form part of a broader “evidence ecosystem”.1 Just as in any other complex ecosystem, there are structures and relationships in the global evidence ecosystem that are required to interact and integrate to function coherently and effectively.2 In this regard, evidence syntheses are now well recognized as a critical component of evidence-based healthcare and evidence-based research, essential to facilitate the trajectory of evidence towards improving future, related activity.

Advances in methodological development over the last three decades have been considerable. This has included a proliferation of new methodologies, methods, tools, and resources to address the many and diverse questions that arise across health science and practice and to synthesize a broad spectrum of evidence types. Alongside these methodological advances, we have also witnessed the development of standards (such as the PRISMA statement and its associated extensions), which have been designed to support authors to transparently report on the conduct of systematic reviews3 and frameworks (such as GRADE) to rate the certainty of evidence.4

While significant progress has been made with evidence synthesis there remain both challenges and opportunities for the global synthesis community. These relate to concerns about research waste and prioritisation;5 consideration of issues related to equity, diversity, and inclusion;6 the potential (and risks) of leveraging artificial intelligence and machine learning;7 the production of “living” reviews;8 and the development of strategies for co-production and meaningful engagement with a variety of potential end users.9

This new edition of the JBI Manual for Evidence Synthesis attempts to provide comprehensive guidance to authors not only in relation to a broad spectrum of systematic review methodologies, but also concerning some of the issues highlighted above.

1.1.1 The JBI Approach

JBI has long understood that evidence can take many forms and that policy and practice are influenced by a variety of understandings and sources of evidence related to feasibility, appropriateness, meaningfulness, and effectiveness.10, 11  As a result, there are currently eight methodologies for systematic and scoping reviews included in this Manual, as follows:

  1. Systematic reviews of qualitative evidence

  2. Systematic reviews of effectiveness

  3. Systematic reviews of textual evidence

  4. Systematic reviews of economic evidence

  5. Systematic reviews of etiology and risk

  6. Mixed methods systematic reviews

  7. Umbrella reviews

  8. Scoping reviews

Some of these methodologies are particularly unique to JBI including those that guide the conduct of qualitative reviews and reviews of textual evidence.  JBI has maintained a long standing, pluralistic approach to what constitutes evidence reflects the need to synthesize the best available evidence to respond to the diversity of questions from health care and is reinforced by JBI’s focus on Feasibility, Appropriateness, Meaningfulness and Effectiveness. 11

Importantly it should be recognized that systematic reviews constitute an important and legitimate form of scholarly enquiry, underpinned by rigorous and sophisticated units of secondary analysis. The science of synthesis has evolved considerably since its inception more than 30 years ago as has the technology developed to support it. JBI’s premier synthesis software, JBI SUMARI (- Home Page | jbisumari ) facilitates the entire systematic review process from protocol to report and includes team and contributor management for effective and efficient collaboration.

1.1.2 Development process

The development process for JBI evidence synthesis methodologies and methods and accompanying guidance is rigorous and regularly reviewed.11

The JBI Scientific Committee is responsible for oversight of all methodological development, comprising a Chair, a range of ex-officio positions from across JBI programs, regional representation from the JBI Collaboration and JBI methodology groups.

JBI Methodology Groups align to each Chapter presented in this manual, to each unique type of evidence synthesis. Each group comprises a Chair and Convenor who work with experts in the field to develop formal guidance for those wishing to engage in work related to JBI programs. Methodology Groups conduct a wide variety of research activities (surveys, exemplar reviews, pilot studies, workshops) to inform and consolidate guidance. Each group is required to report regularly on progress to the JBI Scientific Committee where issues are raised for discussion and debate.

JBI Working Groups are formed to respond to specific, defined issues (such as predatory publishing) that have broad applicability across the diverse types of reviews presented in this Manual and are time limited.

All guidance contained in this Manual has been ratified by the JBI Scientific Committee prior to publication. New methodologies may be included in the manual if submitted by an appropriate JBI Methodology Group and approved by the JBI Scientific Committee. Manuscripts aligned to the latest developments in methodology and methods presented in this Manual are also published periodically in JBI Evidence Synthesis.

1.1.3 External Methodological Guidance

The following external synthesis methodologies have been endorsed for adoption by the JBI Scientific Committee as follows:

Systematic reviews of prevalence and incidence

The PERSyst (Prevalence Estimates Reviews – Systematic Review Methodology Group) is an academic, collaborative group, with the aim to develop and to disseminate methods for systematic reviews of prevalence and cumulative incidence. Methodological articles published by the group can be found here: About . Although this is an external methodology JBI’s synthesis software, JBI SUMARI, can support reviews of this nature.

Systematic reviews of diagnostic test accuracy

The Cochrane Handbook for Systematic Reviews of Diagnostic Test Accuracy is the official guide that describes in detail the process of preparing and maintaining systematic reviews of test accuracy for Cochrane. The Handbook has been produced by the Cochrane Screening and Diagnostic Test Methods Group. It is a guide for those conducting systematic reviews of test accuracy and a reference for more experienced authors and is available at: Cochrane Handbook for Systematic Reviews of Diagnostic Test Accuracy

Systematic reviews of measurement properties

Consensus-based Standards for the selection of health Measurement Instruments (COSMIN) is an initiative of an international multidisciplinary team of researchers with a background in epidemiology, psychometrics, medicine, qualitative research, and healthcare who have expertise in the development and evaluation of outcome measurement instruments. A comprehensive user manual for systematic reviews of outcomes measurement instruments is available on the COSMIN website: Guideline for Systematic Reviews of Outcome Measurement Instruments • COSMIN