Knowledge Synthesis and Covidence

“Systematic reviews aim to provide a comprehensive, unbiased synthesis of many relevant studies in a single document using rigorous and transparent methods.” (Aromataris & Pearson, 2014)

• Reporting of methods used must be comprehensive and detailed.
• A systematic review confirms current practice, addresses any practice variation, identifies areas for future research, and produces statements to help with decision making.
• A systematic review differs from a literature review in that lit reviews include/exclude articles by subjective choice and the scope of searching tends to be more limited. An SR follows a strict protocol that minimizes bias and searches a wide range of sources.

Protocol

• Defines the objectives and methods of the review, including:
  • Inclusion/exclusion criteria
  • What search sources will be used
  • Outline study selection, appraisal, extraction, and synthesis methods
• Must be published ahead of the SR (the protocol also undergoes a peer review process)
• Protocols must be registered before data extraction
  • Register the protocol on PROSPERO
• Should follow a template

Review Team

• Requires at least two reviewers; it cannot be done alone!
• Should include someone who has expertise on the topic and someone who understands the review process.
• Consider including statistician and methodologist support on the review question.

Example of a Systematic Review

Tricco, A. C., Soobiah, C., Berliner, S., Ho, J. M., Ng, C. H., Ashoor, H. M., Chen, M. H., Hemmelgarn, B., & Straus, S. E. (2013). Efficacy and safety of cognitive enhancers for patients with mild cognitive impairment: A systematic review and meta-analysis. CMAJ : Canadian Medical Association Journal, 185(16), 1393–1401. https://doi.org/10.1503/cmaj.130451

Helpful Tools for Systematic Reviews

Scoping reviews aim to determine the size and scope of the literature on a particular topic.

Munn et al (2018) give some examples below on when a scoping review may be done:

• To identify the types of available evidence in a given field
• To clarify key concepts/ definitions in the literature
• To examine how research is conducted on a certain topic or field
• To identify key characteristics or factors related to a concept
• As a precursor to a systematic review
• To identify and analyze knowledge gaps
• To illustrate the scope of a body of literature by clarifying definitions, determining the boundaries of a topic, and identifying gaps in research

Scoping reviews typically address broad research questions especially compared to systematic reviews. Despite their broader scope, scoping reviews still follow a rigorous process to ensure transparent and replicable methods.

Example of a Scoping Review

Kao, S. S.-T., Peters, M. D. J., Dharmawardana, N., Stew, B., & Ooi, E. H. (2017). Scoping review of pediatric tonsillectomy quality of life assessment instruments. The Laryngoscope, 127(10), 2399–2406. https://doi.org/10.1002/lary.26522

A rapid review is “a form of knowledge synthesis in which components of the systematic review process are simplified or omitted to produce information in a timely manner" (p.1) (Tricco et al., 2015).

This type of knowledge synthesis can be helpful for making evidence-based healthcare decisions within a short timeframe (Khangura et al., 2012).

Like a systematic review, a rapid review uses strict methodology to identify current evidence related to a topic. However, conducting a rapid review takes much less time.

Example of a Rapid Review

Boulos, L., Curran, J. A., Gallant, A., Wong, H., Johnson, C., Delahunty-Pike, A., Saxinger, L., Chu, D., Comeau, J., Flynn, T., Clegg, J., & Dye, C. (2023). Effectiveness of face masks for reducing transmission of SARS-CoV-2: A rapid systematic review. Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, 381(2257), 20230133. https://doi.org/10.1098/rsta.2023.0133

Helpful Tools for Rapid Reviews