Research Guides: Evidence Synthesis: Finding and Appraising Existing Systematic Reviews

Finding Existing Evidence Synthesis

Searching for existing evidence syntheses on a topic related to your own research question can be a good place to start your evidence synthesis process. These evidence syntheses may provide a model for approaching your own review of the literature, including recommended search strategies and resources. Below are links to online libraries of evidence syntheses and evidence documents for health and other areas of policy-making.

What is a Systematic Review?

A systematic review is a comprehensive literature search and synthesis project that tries to answer a well-defined question using existing primary research as evidence. A protocol is used to plan the systematic review methods prior to the project, including what is and is not included in the search.

Systematic reviews are often used as the foundation for a meta analysis (a statistical process that combines the findings from individual studies) and to re-evaluate clinical guidelines.

Systematic review and meta analysis are both types of evidence synthesis methods. Read more about evidence synthesis on the Types of Reviews page of this guide.

Evidence Synthesis Databases

Cochrane Library
A collection of published Cochrane systematic reviews and protocols in medicine and healthcare.
Joanna Briggs Library
A journal of systematic reviews published by the Joanna Briggs Institute, an international nonprofit organization that focuses on researching evidence-based healthcare.
PROSPERO
An international registry for prospective systematic reviews with health-related outcomes.
TRIP Database
A clinical research evidence library that allows searching by PICO.
Systematic Reviews for Animals & Food (SYREAF)
A repository for review protocols and systematic reviews in any area related to food, food production, food safety, animal health, and animal welfare. SYREAF also provides information about carrying out systematic reviews.

Campbell Collaboration
A collection of published reviews and protocols by the Campbell Collaboration, which focuses on reviews outside of clinical medicine.
Health Evidence
A database of systematic reviews on public health interventions.
Epistemonikos
A multilingual evidence library for decisions in health care and health policy.
3iE (International Initiative for Impact Evaluations) Database
An international evidence hub for policymakers and researchers looking for evidence on what works, what doesn’t, and why in agriculture, fishing, forestry, education, energy and extractives.
The Community Guide
A free database of systematic reviews to help practitioners choose programs and policies to improve health and prevent disease in their community.
Evidence for Policy and Practice Information and Co-ordinating Centre (EPPI-Centre)
A centre conducting systematic reviews in education, health promotion, public health, social welfare and international development.

The Collaboration for Environmental Evidence

An open community of scientists and managers working towards a sustainable global environment and the conservation of biodiversity. They provide evidence syntheses concerning environmental policy and practice.

UHM Library Catalog Databases

Any scholarly database with published research in your discipline may include evidence synthesis. Log in through the University of Hawaiʻi at Mānoa library catalog, include “systematic review” as a search term to see what’s been published in your field.

Appraising Evidence Synthesis

There are a number of criteria by which you can assess the quality of an evidence synthesis. Below are the two most common tools used for this purpose.

Critical Appraisal Questions

Is the study question relevant?
Does the study add anything new?
What type of research question is being asked?
Was the study design appropriate for the research question?
Did the study methods address the most important potential sources of bias?
Was the study performed according to the original protocol?
Does the study test a stated hypothesis?
Were the statistical analyses performed correctly?
Do the data justify the conclusions?
Are there any conflicts of interest?