Systematic reviews, scoping reviews and other evidence syntheses

Evidence synthesis:

• also called knowledge synthesis
• uses reproducible and transparent methods to analyze data from multiple primary studies
• refers to evidence that has been:
  • synthesized from a large set of data/studies
  • summarized
  • critically appraised
• synthesized evidence is considered:
  • less biased
  • more rigorous
  • more generalizable

Image: https://libguides.lib.umanitoba.ca/c.php?g=297452&p=4467117

Why do we need evidence synthesis?

• Combining and appraising information from multiple studies:
  • helps ensure clinicians use the most appropriate treatment/medication
  • provides evidence-based information to guide health policy and programming
  • reduces unnecessary repetition of research studies

Evidence synthesis generally involves these steps:

• Stating the objectives of the research
• Defining eligibility criteria for studies to be included and excluded
• Identifying (all) potentially eligible studies
• Screening for inclusion and exclusion
• Extracting data from the final set of screened studies
• Appraising the final set of studies
• Applying statistical analysis, if applicable
• Preparing a structured report of the research

Reference: CIHR. (n.d.) A knowledge synthesis chapter: Stages of knowledge synthesis

Image: Ayala, P. (2020). Screening for studies in systematic reviews, scoping reviews, and other knowledge syntheses: Strategies for improvement. KSIG webinar, April 2020.

For more information and guidance on evidence synthesis, including disciplines outside health sciences, please see materials from the University of Minnesota's Evidence Synthesis Institute

• There are multiple types of synthesis reviews
• It's important to:
  • select the appropriate review method for your research question
    • This interactive tool from the University of Manitoba Libraries can help you choose
    • Try What Review is Right for You for quantitative syntheses only
  • be transparent and clear about your aims, methods, and reporting

Which review is right for you?

• Use this flowchart from Cornell University Library to help you decide which type of review is most appropriate for your project:

References:

Centre for Research Evaluation, London School Hygiene and Tropical Medicine. (n.d.) Evidence synthesis: synthesis methods.

Sutton, A., Clowes, M., Preston, L., & Booth, A. (2019). Meeting the review family: exploring review types and associated information retrieval requirements. Health Information & Libraries Journal, (3), 202. https://doi.org/10.1111/hir.12276