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Systematic Reviews

Seeking Librarian Help?

The National Academy of Medicine, the Cochrane Handbook for Systematic Reviews of Interventions, and the Agency for Healthcare Research and Quality each recommend securing the services of a librarian to plan strategically effective and comprehensive searches:

  1. Eden J, Levit L, Berg A, Morton S, eds. Finding what works in health care: standards for systematic reviews. National Academies Press; 2011.
  2. Higgins JPT, Green S, eds. Cochrane handbook for systematic reviews of interventions [Internet]. Cochrane Collaboration; 2011.
  3. Relevo R, Balshem H. Finding evidence for comparing medical interventions: methods guide for effectiveness and comparative effectiveness reviews [Internet]. Rockville, MD: Agency for Healthcare Research and Quality; 2011.


Levels of Research Evidence

Systematic reviews are considered the highest form of evidence as they are an accumulation of research on one topic. Cochrane Systematic Reviews are considered the most rigorous systematic reviews being done.



Differences between Systematic Reviews & Narrative Literature Reviews
Features Narrative Literature Review Systematic Literature Review
Question Broad Narrow
Source Not usually specified, potentially biased Comprehensive sources and search approach explicitly specified 
Selection Not usually specified, potentially biased Uniformly applied preselected inclusion/exclusion criteria
Evaluation Variable Rigorous critical evaluation
Synthesis Often qualitative, quantitative through meta-analysis* Often qualitative, quantitative through meta-analysis*
*Meta-analysis is a method of statistically combining the results of multiple studies in order to arrive at a quantitative conclusion about a body of literature and is most often used to assess the clinical effectiveness of healthcare interventions ("Meta-analysis", 2008).

Steps for a Systematic Review

  1. Develop an answerable question 
  2. Check for recent systematic reviews  
  3. Agree on specific inclusion and exclusion criteria 
  4. Develop a system to organize data and notes
  5. Devise reproducible search methods 
  6. Launch and track exhaustive search 
  7. Organize search results 
  8. Reproduce search results 
  9. Abstract data into a standardized format
  10. Synthesize data using statistical methods (meta-analysis)  
  11. Write about what you found

Timeline for a Cochrane Review

Table reproduced from Cochrane systematic reviews handbook.

Recommended Guidelines


Green, S., & Higgins, J. P. T. (editors). (2011). Chapter 2: Preparing a Cochrane review. In J. P. T. Higgins, & S. Green (Eds.). Cochrane Handbook for Systematic Reviews of Interventions (Version 5.1.0). Available from

Meta-Analysis. (2008). In W. A. Darity, Jr. (Ed.), International Encyclopedia of the Social Sciences (2nd ed., Vol. 5, pp. 104-105). Detroit: Macmillan Reference USA.