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PHRM 832: Introduction to Evidence-Based Medicine

This guide is intended to be used in supporting the work of the PHRM 832: Introduction to Evidence-Based Medicine class, taught by James Nawarskas.

Breaking Your PICO into a Search

Continuing with the understanding that our PICO is:

In preadolescents with asthma will inhaled corticosteroids suppress normal growth (as compared to treatment without corticosteroids)?


  • Patient/Problem: preadolescents with asthma
  • Intervention: inhaled corticosteroids
  • Comparison: treatment without corticosteroids
  • Outcome: growth at predicted rate

We can break that out and utilize Boolean Operators to create the most effective search. We want to start with Patient/Problem and Intervention in our initial search. We will look for the Comparison and Outcome when we browse abstracts and full text articles. If you are getting a large amount of articles in this initial search you can of course add the additional factors, but many times adding the Comparison and Outcome too early can lead to elimination of important resources.

With that in mind and utilizing the Boolean Operators our search would start by looking something like this:

asthma AND "inhaled corticosteroids"

Check mark icon.Quick Tip: Not sure what these terms even mean? See the Where to Search page to find more information on gathering background information before you begin looking for articles.

Create a Search Using Commands

1. Isolate keywords from your topic.

Image that lists the question "How does cultural competence impact the health care system in the United States? With cultural competence, health care, and United States highlighted to show how to pull them out in a search.

2. Narrow your search results to include all of your keywords using AND.

"United States" AND cultural competence AND health care

Venn diagram that has "United States" AND "Cultural Competence" AND "Health Care" to try and display how when using Boolean Operators the three intersect.

3. Expand your search using OR to find like terms.

"United States" AND "cultural competence" AND ("health care" OR healthcare)

Combining search terms with AND:

  • Narrows your search, reducing the number of results.
  • Makes the search focus more specifically on your topic.

Vin diagram that indicates how AND intersects (example written out in text in this box).

For Example

A search for "United States" yields 314,000 results results

A search for cultural competence yields 1,700 results

A search for cultural competence AND "United States" yields 429 results

Combining search terms with OR:

  • Expands your search and increases number of results.

Vin diagram that indicates how OR intersects (example written out in text in this box).

For Example

A search for "health care" yields 263,000 results

A search for healthcare yields 170,000 results

A search for "health care" OR healthcare yields 317,000 results

Combining search terms with NOT:

  • Narrows your search, decreasing your search results.
  • Tells the search to exclude certain terms.

Diagram that indicates how not works, when you use it for by saying NOT family you find caregiver without the word family (example written out in text in this box).

For Example

A search for caregiver yields 13,300 results

A search for caregiver NOT family yields 6,700 results

Use Quotation Marks to:

  • Narrow your search.
  • Combine search terms that are more than a single word.

This shows the search engine that you want the terms to be found together. The search will look for exactly what you place in the quotation marks, so be sure there are no mistakes.

Vin diagram that indicates how quotation marks keep phrases together (example written out in text in this box).

For Example

A search for United States yields over 500,000 results

A search for "United States" yields about 300,000 results

Use Truncation to:

  • Expand your search.
  • Give your search tool flexibility to find alternate endings for your search term.

Diagram that indicates how truncation works (example written out in text in this box).

Search engines match your exact terms to results; they will not automatically find an alternate version of it. Truncation tells the search to match the root of your term and gives it freedom to find whatever endings it can.

For Example

A search for cultural yields 36,000 results

A search for cultur* yields over 95,000 results

These commands are called Boolean Operators.


1. denoting a system of algebraic notation used to represent logical propositions, especially in computing and electronics.

What does that mean for you?

If you are having a hard time finding what you need, use the Boolean Operators outlined here to more efficiently search databases.

No matter where you are searching - the catalog, Google Scholar, a database you will want to use Boolearn Operators to refine your search to your specifications.

We are indebted to the Butler University Library's And/Or/Not box and to the Sarah Lawrence Create a Search Using Commands box for some of the content displayed here.

Advancing Your Search: Filters

You might be wondering why we didn't add information about the boy's age in that first search. The reason is because many databases, like PubMed, have filters specifically for a person's age. If you are in a resource that doesn't have these filters you would have wanted to search for something along the lines of:

"inhaled corticosteroids" AND asthma AND child*

If you are in a resource like PubMed do the search for

"inhaled corticosteroids" AND asthma

Then on the left hand side of the page select "Show additional filters" and chose "ages." From there you can select the age range you need.

Screenshot of the PubMed filters with the age filter selected

Need more help with PubMed? See our PubMed Guide:

Advancing Your Search: More Terminology

That initial search we did was pretty simple, but it was a way to start without eliminating too many options. Remember: searching is iterative.. You might have to combine multiple searches in multiple databases (hint: this is why Saving & Keeping Track of Searches/Results is so important).

When I add the filter for child I do get closer to some useful results, that search will look like this 

"inhaled corticosteroids" AND asthma AND child*

To advance my search even more though, I might want to think of alternative ways to phrase what I need. Looking at Subject Headings/Terms can be a great way to think of new ways to phrase what I need or even look for articles specifically about my topic. When I do that for this search I could update it to be:

("inhaled corticosteroids" OR "Adrenal Cortex Hormones") AND asthma AND child*

Check mark icon.Quick Tip: OR expands my search and AND narrows it.

Advancing Your Search: Separating the Comparison & Outcome

If I do this search in PubMed I notice a lot of my results discuss issues with growth, so already I have gotten to some useful results. However, I can also  advance my search by plugging in the Comparison OR Outcome elements. Again, you don't want to start with both as this might eliminate many useful articles. That search would look something like:

("inhaled corticosteroids" OR "Adrenal Cortex Hormones") AND asthma AND child* AND (growth OR "bone metabolism" OR "adrenal function")

Keyword and Subject Searching



Natural language words that describe your topic

Pre-defined "controlled vocabulary" that describe what an item is about 

More flexible search - looks for anywhere the words appear in the record

Less flexible search - only the subject fields will be searched

Broader search, but may yield irrelevant results

Targeted search; results are usually more relevant to the topic, but may miss some variations

Keyword searching is how we normally start a search. Pull out important words or phrases from your topic. 

Subject Terms and/or Headings are pre-defined terms that are used to describe the content of an item. These terms are a controlled vocabulary and function similarly to hashtags on social media.

We are indebted to the MIT What are subject headings and keywords? box and Sarah Lawrence Finding Resources Guide for some concepts displayed here.

In the Catalog, subject headings are displayed under "Description" in the record of an item. Click on the arrow to the left of "Description" and then scroll down to the section called "Subjects."




In the Databases, subject headings may be listed as Descriptors, Subjects and/or Subject Headings and are typically located in the Abstract and/or Details of an article.

Subject Headings in PubMed

In PubMed subjects are referred to as Medical Subject Headings (MeSH). Find more information about how to use these on our PubMed: Narrowing a Search Guide:


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Leah Everitt
Health Sciences Library and Informatics Center
Room 215