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Systematic Reviews

A guide to conducting systematic reviews.

Steps in the Process

  1. Defining the topic and developing a protocol with pre-defined eligibility criteria for studies;
  2. Formulating a systematic search that attempts to identify all studies addressing the question and meeting the eligibility criteria;
  3. Appraising the validity of the included studies; and
  4. Synthesizing, interpreting and presenting the findings.

Librarian Assistance

As expert searchers, librarians play an important role in making sure your searches are comprehensive and reproducible.

The Institute of Medicine's Standard 3.1.1 -  Finding What works in Health Care (2011) recommends working with a librarian trained in performing systematic reviews to plan the search strategy, and Standard 3.1.3 states that an independent librarian should peer review the search strategy.
The Methods Guide for Effectiveness and Comparative Effectiveness Reviews from the Agency for Healthcare Research and Quality (AHRQ) recommends that “[a] librarian or other expert searcher should be involved in the development of the search.”

***It is best to include the librarian from the start of the project.***

To set up an appointment for help with your systematic review, fill out our request form.

 

Getting Started: Systematic Reviews

A systematic review "is a scientific investigation that focuses on a specific question and uses explicit, prespecified scientific methods to identify, select, assess, and summarize the findings of similar but separate studies."(1)

A meta-analysis, "sometimes misused as a synonym for systematic reviews",(2) is "a quantitative statistical analysis of several separate but similar experiments or studies in order to test the pooled data for statistical significance".(3)

 

1 Finding What Works in Health Care: Standards for Systematic Reviews, Committee on Standards for Systematic Reviews of Comparative Effectiveness Research, Institute of Medicine. National Academies Press, June 2011.
2 Cochrane Collaboration Glossary (https://community.cochrane.org/glossary).
3 Merriam-Webster (http://www.merriam-webster.com).

From the Centre for Reviews and Dissemination at York University:

Systematic reviews aim to identify, evaluate and summarise the findings of all relevant individual studies, thereby making the available evidence more accessible to decisionmakers. When appropriate, combining the results of several studies gives a more reliable and precise estimate of an intervention’s effectiveness than one study alone. Systematic reviews adhere to a strict scientific design based on explicit, pre-specified and reproducible methods. Because of this, when carried out well, they provide reliable estimates about the effects of interventions so that conclusions are defensible. As well as setting out what we know about a particular intervention, systematic reviews can also demonstrate where knowledge is lacking. This can then be used to guide future research.(1)

1 Systematic Reviews: CRD's Guidance for Undertaking Systematic Reviews in Health Care, Centre for Reviews and Dissemination, University of York, 2009. (http://www.york.ac.uk/inst/crd/index_guidance.htm).

Requirements for doing a systematic review:

  • Have an answerable question. By definition, a systematic review addresses the effects or outcomes of specific interventions. Use PICO to formulate the question.

  •  Write a protocol that includes background (why this systematic review is needed), answerable question, inclusion/exclusion criteria, and methodology.

  • Establish a team to work on the review. Need at least two people to review studies in order to eliminate bias and a librarian to do the literature search. It's helpful if a third reviewer is available when there are disagreements over inclusion/exclusion of specific studies.

  • Allow enough time to go through the process. It can take more than a year, depending on the topic. Starting a review during your final year of medical school is not advisable.

  • A comprehensive search requires careful selection of search terms and involves searching several databases and other resources for published and unpublished studies. This is a time-consuming process, as it usually demands several revisions of search terms and strategies to arrive at the best and most comprehensive search.

  • The large number of search results will require ample time to review for inclusion/exclusion and appraise for quality. More time is needed to extract and analyze data and synthesize findings. Additional time is necessary for writing the final manuscript.