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Nursing: Evidence-Based Practice: Acquiring Evidence

This guide provided information on evidence-based practice in nursing.

EBP Process

1. Ask a clear clinical question

2. Acquire best available evidence

3. Appraise evidence for quality

4. Apply evidence to practice

5. Assess the outcomes

Evidence by Question Type


Systematic Reviews or Meta-Analysis
Randomized Controlled Trials
Clinical Practice Guidelines
Nonrandomized Controlled Trials
Cohort Study or Case-Control Studies
Meta-Synthesis of Qualitative or Descriptive Studies
Qualitative or Descriptive Studies
Expert Opinion

Diagnosis, Prognosis/Prediction

Synthesis of Cohort Study or Case-Control Studies
Single Cohort Study or Case-Control Studies
Meta-Synthesis of Qualitative or Descriptive Studies
Single Qualitative or Descriptive Studies
Expert Opinion


Meta-synthesis of Qualitative Studies
Cohort Studies
Single Qualitative studies
Synthesis of Descriptive Studies
Single Descriptive Studies
Expert Opinion


Randomized Controlled Trials
Cohort Studies
Case Control
Case Series

Economic Analysis

Economic Analysis

Database Search Strategy – Step 1

Identify alternative and keywords to describe each PICO component.

This allows the database to search for relevant articles that may have been indexed using one other alternative words.  These words and terms can (and should) come from many sources, including everyday language and database thesauri.  

Consider the following questions to uncover alternative and keywords for each component: 


Who is the patient? What is the population or disorder of interest? What are key characteristics of the patient, problem or population? What health concerns are of interest? 


What is the intervention or event? What therapeutic, diagnostic, preventative or other health care actions or processes of interest? What do you want to do for the patient or population?  

Comparison (if applicable)

Is there an alternative intervention? What is the intervention being compared to?


What is the effect of the treatment/intervention? What are the results of the intervention? What are you trying to accomplish, improve, or effect?

Tip: Consult the MeSH thesaurus at

MeSH (Medical Subject Headings) is the controlled vocabulary thesaurus that indexers at the U.S. National Library of Medicine use to classify articles in PubMed. MeSH terms are also used by many other nursing and health research databases

Tip: Keep a record of the words used in your search.

Database Search Strategy – Step 2

This step requires you to combine alternative words and components using Boolean operators and other search techniques.  View the Advanced Search Strategies handout
Tip: When using Boolean operators, remember to combine all the synonymous/alternative words that represent one component with OR. Combine the sets of different component with AND and use NOT sparingly.
Tip: Avoid searching for outcomes since the words used to describe outcomes can be very complex and not well indexed in databases.

Database Search Strategy – Step 3

Use database limits and filters to target specific content and generate more relevant results. The limits and filters vary by question and database.  You can learn more about a database's limits or filters by consulting the help pages.

Database Search Strategy – Step 4

There are many way in which you can revise your search or strategy if your initial results do not meet your research needs. See the following for tips on modifying your search to find more relevant results.

Tip: Broaden the search by including more alternative/keywords. 
Tip: Try a different database because no single database contain all the literature on a topic.
Tip: Try a basic search with a few selected keywords
Tip: Perform an advanced search which combines only one or two concepts. For example, you may want to run a search of (Concept 1 words) AND (Concept 2 words) or (Concept 3 words) AND (Concept 4 words).

Library Liaison for Nursing Students & Faculty

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Marcia Keith
Student Union & Library Building: Rm 203-B
Subjects: Health, Nursing

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