Evidence Synthesis & Systematic Reviews

What is evidence synthesis? 

Evidence synthesis is sometimes referred to as “systematic reviews." They are conducted by researchers in a number of disciplines. Regardless of the type review (systematic review, scoping review, umbrella review, etc.), they use systematic, explicit and transparent methods to identify, select, and evaluate sources (studies) for the purpose of synthesizing findings aimed at finding common themes, best outcomes, and data or evidence from studies that can be used to inform healthcare interventions, policy development, and future research.​

Evidence synthesis research teams often include a librarian who can assist with: identifying relevant databases and grey literature sources, providing guidance for search terms, protocol development, and inclusion-exclusion criteria, and conducting, managing, and reporting searches. The following references include additional information about librarian involvement in evidence synthesis projects.

• Rethlefsen, M.L., Farrell, A.M., Trzasko, L.C., Brigham, T.J. (2015). Librarian co-authors correlated with higher quality reported search strategies in general internal medicine systematic reviews. Journal of Clinical Epidemiology, 68(6):617-626.10.1016/j.jclinepi.2014.11.025
• Spencer AJ, Eldredge J.D. (2018). Roles for librarians in systematic reviews: a scoping review. Journal of the Medical Library Association, 106(1):46-56. https://doi.org/10.5195/jmla.2018.82

To identify what type of review might be right for you, check the review decision tree at Cornell University Libraries.

Some examples of review types include: 

• Systematic Reviews include a comprehensive search of the literature to identify studies that answer a specific question and they adhere to a review protocol to ensure transparency and reproducibility. 
• Meta-analysis are a statistical approach to combining data derived from studies that are retrieved in a systematic review.
• Rapid Reviews apply systematic methods but use a shortened timeframe to locate and appraise sources. 
• Scoping Reviews explore broad research questions to map key concepts and gaps in the literature. 
• Umbrella Reviews compile evidence from other reviews to address a broad problem for which there are competing interventions.