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Reviews & systematic reviews  

Last Updated: Sep 29, 2015 URL: Print Guide RSS Updates
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What is a systematic review?


A properly conducted systematic review faithfully summarizes the evidence from ALL relevant studies on the topic of interest, and it does so concisely and transparently. (Cook, 1997)

A review of a clearly formulated question that uses systematic and explicit methods to identify, select and critically appraise relevant research, and to collect and analyze data from the studies that are included in the review. (Cochrane Collaboration)

How does a systematic review (SR) differ from a "regular" review?

Systematic reviews and traditional narrative reviews compared


Good quality systematic review

Traditional narrative review

Deciding on review question

Start with clear question to be answered or hypothesis to be tested

May also start with clear question to be answered, but they more often involve general discussion of subject with no stated hypothesis

Searching for relevant studies

Strive to locate all relevant published and unpublished studies to limit impact of publication and other biases

Do not usually attempt to locate all relevant literature

Deciding which studies to include or exclude

Include explicit description of what types of studies are to be included to limit selection bias on behalf of reviewer

Usually do not describe why certain studies are included and others excluded

Assessing study quality

Examine in systematic manner methods used in primary studies, and investigate potential biases in those studies and sources of heterogeneity between study results

Often do not consider differences in study methods or study quality

Synthesizing study results

Base their exclusions on those studies which are most methodologically sound

Often do not differentiate between methodologically sound and unsound studies

from: Petticrew M. Systematic reviews from astronomy to zoology: myths and misconceptions BMJ 2001 Jan 13; 322:98-101.


What is a meta-analysis?

A meta-analysis begins with a systematic review and selects studies which are very similar in terms of exact question studied and methods. All subjects are grouped as though they were one large pool, and statistical analysis is run on that group to resolve conflicting results or identify patterns.

Are there standards for systematic reviews?

Yes, the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) Guidelines provide a minimum set of items for reporting in systematic reviews and meta-analyses. View and download them from this link.

How much work is involved in writing a systematic review?

A systematic review represents a commitment of several months from a team of people. Those most likely to be involved include your research advisor, a person very knowledgable in the field of your study, your librarian and a statistician.

What is the role of the librarian?

The conduct of a systematic review depends heavily on the scope and quality of included studies. If you miss important studies, your review will be considered lower quality. Your librarian can suggest the most appropriate databases and other resources to search, formulate a thorough search strategy for each, and help you develop inclusion/exclusion criteria for the many articles that will be retrieved. To meet PRISMA guidelines, the search strategy should be included in its entirety for at least one of the databases used, such that it can be reproduced. Therefore, the librarian, in most cases, contributes substantively to the methods section of the article.

How can I find systematic reviews?

To see a list of examples to become more familiar with SRs, see Georgia State University's LibGuide.

To find out if an SR has already been done on your topic, search for the topic, then for "systematic review" in the title. This should work because PRISMA states that these words should appear in the title of all systematic reviews. However, not all SRs follow PRISMA, so your librarian can help if you come up empty-handed or want to search more thoroughly.


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