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Physician Assistant Systematic Review


A systematic Review stands apart from a typical literature review, because of the search strategy. A systematic review is a comprehensive analysis of the research done on this topic. To ensure that you have found a comprehensive list of sources, you need to develop an exhaustive search strategy.

Your search strategy should include:

  1. Breaking your question into concepts (see keyword exercise in Formulate a Searchable Question)
  2. Identifying text words for each concept
  3. Identifying MeSH or other subject headings for each concept
  4. Connecting concept together through Boolean search logic
  5. Combine all keywords and subject headings in all possible combinations
  6. Apply relevant filters (Matching what you have chosen to exclude and include in your protocol)
  7. Search across multiple platforms

Limit/Exclusion Criteria

You will need to spell out what you wish to include and exclude in your search. These exlcusions will determine how you limit your search.

Here are some limits that you should think about as you structure your search: 


Criteria Questions to Ask Advise from the Cochrane Handbook for Systematic Reviews of Interventions  (2008, p. 134)
Time Period Will your review be restricted by year of publication, or is it important that you cover all years? "Date restrictions should be applied only if it is known that relevant studies could only have been reported during a specific time period, for example if the intervention was only available after a certain time point."
Language Should you restrict to English language publications only? "Whenever possible review authors should attempt to identify and assess for eligibility all possibly relevant reports of trials irrespective of language of publication. No language restrictions should be included in the search strategy."
Publication Type Are you restricting your search by publication type? "Format restrictions such as excluding letters are not recommended because letters may contain important additional information relating to an earlier trial report or new information about a trial not reported elsewhere."
Geographic Considerations Are there any geographic considerations to include in your search strategy? For example, if you were researching Chinese herbal medicine you would need to consult Chinese literature.


Boolean Operators

To narrow your search to relevant studies, you will need to combine your concepts using boolean operators. 

Databases use a specific search language to optimize your search. This language is called Boolean. Each database has slightly different rules. You can verify those rules with Cochrane's syntax guide.  But generally you want to follow these basic rules:


Boolean Search Logic

1.Boolean operators: AND, OR, NOT

  • Use AND to combine concepts for fewer results
    • “Aspirin” AND “Children” AND “Reye’s Syndrome”
      • The results  will be limited to only those items that mention both Asprin and Children and Reye’s Syndrome
  • Use OR to search for a single concept using synonymous or related terms.
    • “Kidney Disease” OR “Renal Disease”
      • Results will be expanded to results that mention the either Kidney Disease or Renal Disease
  • Use NOT to eliminate unrelated results.

a.Not Adults

  • Combine And and OR and NOT phrases to construct complicated search logic
    • (“Kidney Disease” or Renal Disease) AND “Children”
      • Search logic defaults to reading the search string from left to right. Use brackets to specify the order you would like the database to read the search (Think algebra problem)

2.Truncation and Wildcard: * ?

  • Use Truncation for searching alternate endings.
    • Child*: Child, Childs, Children, Childhood
  • Use Wildcard to replace a single letter in the middle of a word
    • Wom? n: woman and women
  • Truncation and wildcard symbols vary among databases. Always check the Help menu.

3.Phrase Searching: “ ”

  • Use Quotation marks to search for entire phrases
    • “Kidney Disease” and “Renal Disease”
For more information: Cochrane Syntax Guide

Searching with MeSH

MeSH stands for Medical Subject Headings and is the index terms associated with articles found in Medline (searchable through PubMed and Medline databases). MeSH reviewers read articles before they go into MEDLINE and assign appropriate subject headings to the article. You can search with MeSH terms, but you can also search the MeSH database to find relevant MeSH terms for your topics. 

Search MeSH Database

The MeSH database is a resource found through the National Center for Biotechnology Information (NCBI) who also publishes PubMed. To search the MeSH Database start in PubMed. And change the database by the search bar to MeSH. 

Use natural language or know MeSH term. If the term is not a MeSH term, the search will automatically look for official related terms and show relevant MeSH terms. 

In the entry for each term, there will be a definition, possible subheadings that you can add to your search, related natural language terms, and a MeSH category tree. MeSH terms are hierarchical in nature, and the tree can help you explore related terms. 

If you wish to add a MeSH term to your PubMed search, you can click "add to search builder" on the right-hand side of the screen. 

You can add multiple MeSH terms or keywords to this search builder to customize your Pubmed search.