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Evidence Based Nursing: Evidence

Search, Appraise, Synthesize

It's important that you are familiar with how you expect or can expect your question to be answered within the literature. During the E phase of the PET process, you must not only find relevant literature, but also appraise each resource for its relevancy and applicability to your environment. Once you have successfully created a search strategy, searched bibliographic databases, and located relevant literature resources, it is important that you and your team are comfortable with the types of evidence, as well as the types of publications you will be appraising. Additionally, because appraisal standards for various publication types differ from one another, understanding what kind of evidence your question is seeking is essential to being prepared for the appraisal and Translation stages of the EBP process.  

*Dearholt & Dang, 2012


Types of Evidence

  Definition Types of Publications Where? 
Translational Literature Research findings that have been translated into guidelines used in the clinical setting.
  • Practice guidelines
  • Protocols
  • Standards
  • Critical pathways
  • Clinical innovations
  • Evidence based care centers
  • Peer reviewed journals
  • Bibliographic databases
  • PubMed
  • National Guideline Clearinghouse 
  • Joanna Briggs Institute. 
Evidence Summaries Summaries of the literature to summarize results of the studies. 
  • Systematic reviews
  • Integrative reviews
  • Meta analysis
  • Meta synthesis
  • Evidence synthesis
  • Library catalogs
  • PubMed
  • The Cochrane Library 
Primary Evidence Data collected directly from patient or subject contact
  • Hospital data
  • Clinical trials
  • Peer-reviewed research journals
  • Conference reports 
  • PubMed
  • Library Catalogs
  • Institutional repositories.
  • HCUP


Haynes Levels of Evidence

Step 1: List keywords

  • For each applicable PICO part that's used in the PICO question, list searchable keywords to identify each topic.


    Atrial Fibrillation 







Step 3: Translate into Bibliographic Database

  • Pick a resource like PubMed or CINAHL to translate the strategy from Step 2. into the bibliographic database. 
  • Construct each PICO active PICO element separately by searching the Controlled Vocabulary like MESH or CINAHL Headings. 
    •  Ex: ("Myocardial Infarction"[Mesh])
  • Add in keywords and non-standardized terms into the parenthesized PICO portion of the strategy using OR. Remember to always use quotations around phrases. 
    • Ex: ("Myocardial Infarction"[Mesh] OR "heart attack")
  • Once you've constructed each PICO piece separately, combine each parenthesized portion using AND
    • Ex: ("Myocardial Infarction"[Mesh] OR "heart attack") AND ("Anticoagulants"[Mesh] OR "Warfarin"[Mesh])

Type of questions and Studies

Step 2: Group Concepts using AND, OR, NOT

Atrial Fibrillation  

Anticoagulation OR 



  • Write out the strategy using parentheses and Boolean operators: 
    • (Atrial Fibrillation) AND (Anticoagulation OR Warfarin)

Step 4: Add Filters and/or Limits

After searching the database using the strategies above, take note of the first few results as well as how many total results the strategy returned. If patient age is essential to the analysis of the literature, filter results to reflect that. Next, refer to your question type, evidence types and publication types and filter your results to show only those publication types you and your team decided on. Use the 6S pyramid shown to the right to help you distinguish between the levels of evidence and the types of studies included in each pyramid level