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Systematic Reviews

This guide will introduce you to the process of conducting a systematic review.

Smart Searching

TIP: Look for systematic reviews that have already been published.

This serves two purposes:

  1. Helps ensure that the work has not already been done
  2. Provides examples of search strategies for your topic

Search Strategy

The goal of systematic review searches is to identify all relevant studies on a topic. Therefore, systematic review searches are typically quite extensive. It is necessary, however, to strike a balance between striving for comprehensiveness and maintaining relevance when developing a search strategy. Increasing the comprehensiveness (or sensitivity) of a search will reduce its precision and will retrieve more non-relevant articles.

For more information, check out IOM Standards for Systematic Reviews: Standard 3.1: Conduct a comprehensive systematic search for evidence

The goal of a systematic review search is to maximize recall and precision while keeping results manageable. Recall (sensitivity) is defined as the number of relevant reports identified divided by the total number of reports in existence. Precision (specificity) is defined as the number of relevant reports identified divided by the total number of reports identified.

Issues to consider when creating a systematic review search:

  • All concepts are included in the strategy
  • All appropriate subject headings are used
  • Appropriate use of explosion
  • Appropriate use of subheadings and floating subheadings
  • Use of natural language (text words) in addition to controlled vocabulary terms
  • Use of appropriate synonyms, acronyms, etc.
  • Truncation and spelling variation as appropriate
  • Appropriate use of limits such as language, years, etc.
  • Field searching, publication type, author, etc.
  • Boolean operators used appropriately
  • Line errors: when searches are combined using line numbers, be sure the numbers refer to the searches intended
  • Check indexing of relevant articles
  • Search strategy adapted as needed for multiple databases

Databases for Searching the Literature and Grey Literature

PubMed Logo

Search PubMed:   

Search Filters

Clinical Queries in PubMed

These search strategies help find citations that correspond to a specific clinical study category

Cochrane Handbook

See Part 2, Section 6.4.11: Search Filters

InterTASC Information Specialists' Sub-Group

The ISSG has developed a quality checklist to assess published filters designed to retrieve records by specific study design.

Blog: PubMed Search Strategies

This blog has been created to share PubMed search strategies

Articles on Search Filters in PubMed

Runs a search in PubMed for articles about search filters.

Common Search Strategies (Filters) to Limit Retrieval

Cochrane Filter for Humans Only:

NOT (animals [mh] NOT humans [mh])

Duke Modified Cochrane Strategy for Randomized Trials in PubMed:

(randomized controlled trial[pt] OR controlled clinical trial[pt] OR randomized[tiab] OR randomised[tiab] OR randomization[tiab] OR randomisation[tiab] OR placebo[tiab] OR drug therapy[sh] OR randomly[tiab] OR trial[tiab] OR groups[tiab] NOT (animals[mh] NOT humans[mh]) NOT (Editorial[pt] OR Letter[pt] OR Case Reports[pt] OR Comment[pt]

Documenting and Reviewing Search Strategies

IOM Standards for Systematic Reviews: Standard 3.4: Document the search

PRISMA Checklist

Cochrane Handbook for Systematic Reviews of Interventions

See Part 2, Chapter 6.6: Documenting and reporting the search process

Analysis of the reporting of search strategies in Cochrane systematic reviews

Yoshii, A. (2009). Journal of the Medical Library Association, 97(1): 21-29. PMID: 19158999

PRESS Instrument for Reviewing Search Strategies

Checklist for peer review of search strategies

Term Discovery and Analysis

Search for terms and check "highly related concepts" to see MeSH that are common among your results.

PubMed PubReMiner

Run a query and see what journals, MeSH, etc., are represented among your results.

MeSH On Demand

A Tool from NLM that suggests MeSH terms based on text you provide.

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