PubMed

As you become more comfortable with searching in PubMed, you may want to start building more complex search strategies. 

This can allow you take more control over the search and have the database do more precisely what you want it to do.  This can be especially important when creating comprehensive searches for projects like systematic or scoping reviews.

The below tools are not specific to PubMed, but can be helpful in creating advanced PubMed searches.

**Important** All of these tools will turn off the Automatic Term Mapping feature

What is Truncation?

Truncation is a tool that is available in many databases, including PubMed.  It allows you to easily search for all the different forms of a given root-word by adding the truncation symbol: * (asterisk)

For example, a search for nurs* would retrieve articles that include the terms nurse, nurses, and nursing.

Things to Keep in Mind With Truncation

Think carefully about where you are cutting your word.  You want it to be broad enough to capture all the relevant forms of the word, but also not so broad that it floods your results with irrelevant items.

What are the forms you are hoping to capture?  You should have a rough list in your head of what you are expecting to find with the truncated term.

• If you are truncating a verb that ends in -e, remove it in order to capture the -ing form.  For example, smok*
• Are there forms you do not want to capture?  For example, if you truncate child* to retrieve child, children, and childhood, you will also capture articles talking about childbirth, childless, childish, and childrearing.  In this case, it might make more sense to spell out all the forms that you want.
• PubMed requires that you have more than 3 letters in order to use truncation.  So, if you want to search for articles about cerebrovascular accidents and use the abbreviation of CVA, you will need to spell out the plural: cva OR cvas
• Truncation turns off the Automatic Term Mapping process.  If you still want some of the ATM terms to be searched, you will have to manually add them back into your search strategy, rather than relying on PubMed doing it automatically.

What are Field Tags?

PubMed defaults to searching in All Fields.  If you would like to specify a certain field(s) to be searched instead, you can use field tags to tell the database what you want.

For example, you can choose to only search in the MeSH field or the Title/Abstract fields.

Common Field Tags

Some of the most commonly used PubMed field tags are below:

• [mesh]: searches only in the MeSH field and allows the MeSH Explosion to still take place
• [mesh:noexp]: searches only in the MeSH field, but turns the MeSH Explosion feature off
• [tiab]: searches only in the Title and Abstract fields; good to use with keyword synonyms
• [tw]: searches in the designated Textword fields; this includes the Title, Abstract, MeSH (without explosion), and more; this one is a little broader than [tiab], but not quite as broad as [all fields], and can also be a good one to use with keyword synonyms
• [au]: searches only in the Author Name field
• [ad]: searches in the Author Affiliation field; you can use this field to look for Ohio State or Wexner Medical Center authors

Check out the below link for all of the Field Tags available in PubMed and a description of what they will search.

Things to Keep in Mind With Field Tags

• PubMed understands terms searched with field tags to have implied quotation marks around them. 
  • For example, physical therapy[tw] = "physical therapy"[tw]. 
  • If you want your terms to be able to be split up, you would want to tag each of them individually (physical[tw] AND therapy[tw]).
• Using Field Tags turns off the Automatic Term Mapping process.  If you still want some of the ATM terms to be searched, you will have to manually add them back into your search strategy, rather than relying on PubMed doing it automatically.

What is Phrase Searching?

If you are using a multi-word search term in your search, such as physical therapy, you will want to think about how important it is that they stay together in order to still be relevant. 

If you want the terms to stay together and in the order you put them into the search box, you can put them into quotation marks to search them as a phrase.

For example, if you are looking for articles about the young adult population, you would probably want the terms young and adult to stay together.  If they get split apart, they start to become too broad to be relevant.

However, sometimes it may be better to allow the terms to be split up.  For example, breast cancer could also be described as cancer of the breast or breast and ovarian cancer.

Things to Keep in Mind With Phrase Searching

• Think carefully about how your terms might realistically appear in the literature.  Approach this step with an open mind.
  • You don't want to search with a lot of long and complex phrases that may not occur exactly as you entered them very often.  This will make your search too narrow, and you will potentially miss relevant articles.
  • You also do not necessarily want to allow all of your search terms to be split apart, as some may need to stay together to stay relevant.
• Using Quotation Marks turns off the Automatic Term Mapping process.  If you still want some of the ATM terms to be searched, you will have to manually add them back into your search strategy, rather than relying on PubMed doing it automatically.
• Unfortunately, PubMed does not allow the use of Proximity Operators.  These are tools available in some other databases that allow you to tell the database that the terms need to appear within a certain number of spaces from each other.  As such, your terms in PubMed will need to be all or nothing, either completely split up or completely together.