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Systematic Reviews

Search Terms

After finalizing your research question, you want to narrow down the question into searchable concepts.  Using a framework will make it easy to identify which topics to search.  To start your list of keywords you should develop a list of concepts, write down relevant keywords to search with, and map concepts to controlled vocabulary.  Relevant keywords can be identified by knowing a bit about the topic ahead of time.  By doing some preliminary searching, you can assess the volume of articles you will be working with and find some example articles you wish to include in the review.  The example articles will show what subject terms are applied to the article, and provide additional ideas for keywords to use.

*TIP*

Be sure to map all keywords in each databases' thesaurus.  You do not want to search one database with the complete list of terms, and search another with only a subset of those terms.  An easy method to organize your terms is to use a table.

Research question: Does obesity lead to heart disease and strokes?

Topic Keywords
Natural language
Pubmed
MeSH
CINAHL
Subject Headings
Academic Search Complete
Subject Terms
obesity obesity
overweight
obese
morbidly obese
"Obesity"[Mesh]
"Obesity, Morbid"[Mesh]
(MH "Obesity")
(MH "Obesity, Morbid")
DE "OBESITY"
DE "MORBID obesity"
heart disease heart disease
cardiac diseases
heart disorders
cardiovascular
"Heart Diseases"[Mesh] (MH "Heart Diseases") DE "HEART diseases"
stroke stroke
cerebrovascular accidents
"Stroke"[Mesh] (MH "Stroke") DE "STROKE"

 

Mapping Terms to Controlled Vocabulary

The controlled vocabulary used in PubMed is called Mesh, Medical Subject Headings.  You can locate MeSH terms by searching the MeSH database.  MeSH terms can be used in other databases, such as CINAHL and Cochrane.

Begin at the MeSH database

1. Enter in one keyword for your first concept
2. Review the results, and click on the term that matches your keyword
3. You will now be on the MeSH record.  The structure of a MeSH record is laid out starting with the MeSH term, followed by the scope note or definition of the term.  The subheadings are the check boxes, which allow you to select sub-topics within your overall MeSH term.  The entry terms are a list of terms that could have been put into the search box, and it would have taken us to this same place.  The very bottom of a MeSH record has the thesaurus hierarchy.  Any term above and to the left is boarder in concept, and any term below and to the right is narrower in concept.  All the terms are hyperlinked, making it easy to look for other terms to use in your search string.

4. Click "add to search builder" to have the term mapped to the MeSH field.  Copy/paste this format into your term table.
5. Continue collecting MeSH terms for each keyword.  Review the thesaurus at the bottom on the MeSH record to find other terms that you may not have added as a keyword.  Keep in mind that not all terms will be available as a MeSH term.  This is why you search with keywords and controlled vocabulary, to cover multiple methods of retrieving relevant articles.
6.  Once complete, either map your terms with the other databases you will be using, or begin developing your search string.
 

The controlled vocabulary used in CINAHL is called CINAHL Subject Headings.  You can locate terms by searching the thesaurus.

Begin at CINAHL

1. Click on CINAHL Subject Headings in the top navigation bar.
2. Enter in one keyword for your first concept.  Use either the "term begins with" or "term contains" option.
3. Review the results, and check the term that matches your keyword.  CINAHL provides a definition of the term by hovering over the little speech bubble to the right of the term.
4.  The selected term will appear on the right, with the option to include all subheadings, to explode the term, or use the term as a major concept.

Exploding the term will retrieve results for any articles indexed with the term, plus any articles indexed with narrower terms.  The narrower terms are found under the term you selected in the subject headings.

A major concept only finds articles for which the subject heading is a major point of the article.

5. Click "search database" to have the term mapped to the subject heading field.  Copy/paste this format from the search box into your term table.
6. Continue collecting terms for each keyword.  Review the thesaurus to find other terms that you may not have added as a keyword.  Keep in mind that not all terms will be available as a subject heading.  This is why you search with keywords and controlled vocabulary, to cover multiple methods of retrieving relevant articles.
7.  Once complete, either map your terms to the other databases you will be using, or begin developing your search string.

The controlled vocabulary used in PsycINFO is called APA Thesaurus of Psychological Index Terms.  You can locate terms by searching the thesaurus.

Begin at PsycINFO

1. Click on APA Thesaurus of Psychological Index Terms in the top navigation bar.
2. Enter in one keyword for your first concept.  Use either the "term begins with" or "term contains" option.
3. Review the results, and click on the term that matches your keyword.  You will see a definition of the term, plus boarder, narrower or related terms.
4.  Check the term, including the option to explode the term or use the term as a major concept.

Exploding the term will retrieve results for any articles indexed with the term, plus any articles indexed with narrower terms.

A major concept only finds articles for which the subject heading is a major point of the article.

5. Click "add" to have the term mapped to the indexed term field.  Copy/paste this format from the search box into your term table.
6. Continue collecting terms for each keyword.  Review the thesaurus to find other terms that you may not have added as a keyword.  Keep in mind that not all terms will be available as a subject heading.  This is why you search with keywords and controlled vocabulary, to cover multiple methods of retrieving relevant articles.
7.  Once complete, either map your terms to the other databases you will be using, or begin developing your search string.

The controlled vocabulary used in Academic Search Complete is called subject terms.  You can locate terms by searching the thesaurus.

Begin at Academic Search Complete

1. Click on Subject Terms in the top navigation bar.
2. Enter in one keyword for your first concept.  Use either the "term begins with" or "term contains" option.
3. Review the results, and click on the term that matches your keyword.  You will see a definition of the term, plus boarder, narrower or related terms.
4.  Check the term, including the option to explode the term.

Exploding the term will retrieve results for any articles indexed with the term, plus any articles indexed with narrower terms.

5. Click "add" to have the term mapped to the indexed term field.  Copy/paste this format from the search box into your term table.
6. Continue collecting terms for each keyword.  Review the thesaurus to find other terms that you may not have added as a keyword.  Keep in mind that not all terms will be available as a subject heading.  This is why you search with keywords and controlled vocabulary, to cover multiple methods of retrieving relevant articles.
7.  Once complete, either map your terms to the other databases you will be using, or begin developing your search string.

The controlled vocabulary used in SPORTDiscus is called Thesaurus terms.  You can locate terms by searching the thesaurus.

Begin at SPORTDiscus with Full Text

1. Click on Thesaurus in the top navigation bar.
2. Enter in one keyword for your first concept.  Use either the "term begins with" or "term contains" option.
3. Review the results, and click on the term that matches your keyword.  You will see a definition of the term, plus boarder, narrower or related terms.
4.  Check the term, including the option to explode the term.

Exploding the term will retrieve results for any articles indexed with the term, plus any articles indexed with narrower terms.

5. Click "add" to have the term mapped to the indexed term field.  Copy/paste this format from the search box into your term table.
6. Continue collecting terms for each keyword.  Review the thesaurus to find other terms that you may not have added as a keyword.  Keep in mind that not all terms will be available as a subject heading.  This is why you search with keywords and controlled vocabulary, to cover multiple methods of retrieving relevant articles.
7.  Once complete, either map your terms to the other databases you will be using, or begin developing your search string.

Buliding your Search String

Once all terms have been identified, you need to put them together in a search string.  You can export your search strategy in addition to the results, to use in your search documentation.

A search string will generally look like:

(Topic A term 1 OR Topic A term 2) AND (Topic B term 1 OR Topic B term 2) AND (Topic C term 1 OR Topic C term 2)

If searching PubMed with our example research question, the search string would look like:

(obesity OR overweight OR obese OR "morbidly obese" OR "Obesity"[Mesh] OR "Obesity, Morbid"[Mesh]) AND ("heart disease" OR "cardiac diseases" OR "heart disorders" OR cardiovascular OR "Heart Diseases"[Mesh]) AND (stroke OR "cerebrovascular accidents" OR "Stroke"[Mesh])

The search string above was developed for PubMed.  When adapting the string for another database, you want to have the strings operate as similarly as possible.  You would replace the MeSH terms for the controlled vocabulary of the other databases used, if MeSH is not an option in the other database.  You can search CINAHL and Cochrane with MeSH terms.

The search string above is also searching with keywords and MeSH terms.  The MeSH terms will be searched in the MeSH field.  The keywords will be searched in all fields, like the title, abstract, journal name, etc.  You have the option to limit your keyword search to just particular fields, like only the title or abstract.  If you use the second option, you will need to know the field codes for the databases you are searching and update them in the different search strings.

PubMed field codes

How to find EBSCO databases field codes (CINAHL, PsycINFO, Academic Search Complete, SPORTDiscus)

Field codes are database specific. To find the field codes for a particular database, first navigate to one.

1. Click on the Choose Databases link above the Find field
2. Click Detailed View in the resulting window.
3. Click the More Information link for the database
4. Click the Searchable Fields link
5. All the field codes are listed with detailed explanations of what they mean

Contact a librarian if you need assistance with using field codes.

The search string should be tested in a database to assess what results are being pulled.  While reviewing the results, ask yourself these questions.

1. Am I seeing a lot of relevant results?
2. Am I seeing the amount of results I expected?
3. Am I getting too many articles that are not exactly what I wanted?

If you are unhappy with the results, you may need to modify the search string or add some search limits.  If there are too many irrelevant articles, you will need to figure out which term you are using is causing those articles to appear.  Try testing the search with and without the problem term.  If you are happier with the results without the term, then it can be dropped from the search string.  If you are loosing too many relevant articles by dropping the term, then you will remove irrelevant articles in the analysis phase.

It is highly recommended you work with a librarian during the search planning phase.  Librarians are searching experts and can devise a sophisticated search string that will yield great results.

Advanced Searching options

Truncation

Truncation allows you to search root words with various endings.

Example
osteopath* will search for results of osteopath, osteopathy, or osteopathic

Wildcards

Wildcards work similar to truncation, but are used at the beginning or the middle of a term.

Example
wom*n will search for results of woman and women

Proximity searching

Proximity operators allow you to search for words within a certain proximity of each other.

Example

breast NEAR/2 feeding will locate the word breast within two two words of feed.  It does not matter their order.

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Symbols and syntax for advanced searching options will differ from database to database.  You can find the correct option to use in the database help section or by contacting a librarian.

Working with a Librarian

As a team member, the librarian can select or suggest which terms to use for the search, map to appropriate controlled vocabulary, design the search strategy, save/collect the search results and share with team members, and draft the search method.

If the librarian is serving as an advisory role, assistance and education is provided on the following items.

  • Assist in identifying major topic areas
  • Educate the team on how to select keywords
  • Educate the team on how to find controlled vocabulary
  • Educate the team on how to set up the search string
  • Review the final list of search terms and make suggestions