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Literature Searching: Overview

Learn more about how to use library resources to search for clinical information.

Videos and tutorials to help you get started!

Search Techniques

Before you start your search, it is important to have a well-built question. One way to construct a well-built question is to use the PICO model. PICO stands for patient/population, intervention, comparison and outcomes. 

Patient/Population Intervention Comparison Outcomes

Who is your patient?

  • Age, sex, race or patient
  • Primary problem
  • Health status

What do you plan on doing for the patient?

  • Diagnostic test
  • Medication
  • Procedure

What alternative are you considering?

  • Another test, medication or procedure
  • Watchful waiting

What do wish to accomplish?

  • Accurate diagnosis
  • Relieve or improve symptoms
  • Maintain function

Example:  Is adherence to the Mediterranean Diet associated with reduced risk of heart attack?

Patient/Population Intervention Comparison Outcomes
  • Adult
  • History of heart disease
  • Mediterranean Diet
  • Typical diet
  • No comparison
  • Reduction in heart attacks

When you go to search the databases, you may not use all these terms in your search. For instance, you may start out using only the terms Mediterranean Diet and heart attacks.

  • If you retrieve too many results, add more terms to your search, or add more specific terms.
  • If you retrieve too few results, use fewer or more broad terms. 

Learn more about putting together your search terms in the Boolean Operator section. 

Use Boolean Operators to combine together parts of your search. Most databases recognize the use of Boolean Operators, and it is usually recommended that you capitalize AND, OR and NOT for the database to recognize these terms as Boolean Operators. 

AND
AND

Narrows your search. Finds citations that include ALL the terms. 

Use AND to combine together separate topics. 

Example: Mediterranean Diet AND heart attack finds articles that include both these terms. 

OR
OR

 Broadens your search. Finds citations that include ANY of the terms. 

Use OR to combine together synonyms or related ideas. 

Example: heart attack OR myocardial infarction finds articles that contain either of these terms.

NOT
NOT

Narrows your search. Removed citations that contain a term. 

Use with caution! You will lose out on citations that contain an off-hand mention of a term. 

Example: Mice NOT rabbit finds articles that only refer to mice. If an article happened to mention rabbit, this article would not be included from the search results. 

()
Parentheses

Narrows your search. Used to combine groups of terms and allows you to create a more complex search.

Example: (heart attack OR myocardial infarction) AND Mediterranean Diet finds articles on that refer to Mediterranean Diets and either heart attacks or myocardial infarction. 

 

Phrase Searching

Use quotes to search for an exact phrase. This technique is useful for searching names of programs or institution names. Let's see how this works in PubMed

Community Oriented Primary Care versus “Community Oriented Primary Care”

See the difference between these searches? In the first search, the four terms may appear in different sentences or paragraphs. With quotes, the terms are kept together, in exact order.

Truncation

Truncation uses a wildcard character to search for all possible endings of a word. Use to find alternate endings of a word, or to find the plural form of a word. Many databases use an asterisk as a wildcard.

Example: Nutrition* = finds nutrition, nutritional, nutritionally, nutritionist, nutritionists 

Careful, PubMed can only handle 600 variations at a time. Truncating compu* will cause PubMed to give an error message.

MeSH - Medical Subject Headings

MeSH is controlled vocabulary terms that are applied to articles in MEDLINE/PubMed. Controlled vocabulary terms are used to ensure that articles on the same subject are grouped together regardless of the terminology used in the article. They also provide uniformity and consistency to the indexing of biomedical literatures, ensuring that searches can perform a systematic search of the literature.

Consider the age group of a person age 13 - 18. People of this age may be described as teens, adolescents, youth. Any article in MEDLINE that refers to this age group would get tagged with the MeSH term "Adolescent."

Controlled vocabulary terms take some of the guesswork out of searching because you don't need to figure out all the ways to describe a topic.

For a more in-depth introduction to MeSH, visit the MEDLINE/PubMed Medical Subject Heading tutorial. 

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