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Graduate Nursing


Evidence-based models use a process for framing a question, locating, assessing, evaluating, and repeating as needed. PICO elements include: Problem/Patient/Population, Intervention/Indicator, Comparison, Outcome, and (optional) Time element or Type of Study.

1. Frame the Question

  • Write out the information you need in the form of a question.
    • For example:
      • Does hand washing among healthcare workers reduce hospital acquired infections? 
      • The question above includes the PICO elements:

(problem, patient, or population): hospital acquired infection
(intervention/indicator): hand washing
C (comparison): no hand washing; other solution; masks
O (outcome of interest): reduced infection

2. Plan a Search Strategy

  • Identify the major elements of your question, and translate natural language terms to subject descriptors, MeSH terms, or descriptors. 
  • TIP: start with the P and the I only to begin your search and keep initial search results broad:

P (Problem/Patient/Population) in Natural Language: hospital acquired infection
P (Problem/Patient/Population) in Database Vocabulary: cross infection [MeSH] / cross infection [CINAHL Subject]
I (Intervention/Indicator) in Natural Language: hand washing
I (Intervention/Indicator) in Database Vocabulary: hand disinfection [MeSH] / handwashing [CINAHL Subject]

  • A simple database search strategy is most effective when it begins with the P AND I: cross infection AND (handwashing OR hand disinfection) 
  • Start with both CINAHL and Medline/PubMed as initial article databases for a scoping search for most health sciences questions.  If your topic has a behavioral/mental health component, also try PsycINFO.

3.  Consider Comparison, Outcome, Time Factors or Type of Study

After viewing the initial search results you may decide to narrow your search with terms for the comparison, outcome, time factors or type of study. You may view results, abstracts, and full text of articles to view the comparison and outcome elements. Use database filters explained in "Filtering the Evidence."

4. Filter the Evidence

  • Use a Boolean Worksheet:
  • Limit your search: Apply filters to the search. You can filter by age, publication year, etc.
  • Broaden your search:
  • Use "Find Similar Results" on the article page.

  • Truncate one or more of your search terms
  • Truncation symbols in a database allow you to search on a root word and include plurals. For example:
    • Diab* (to retrieve diabetes, diabetic, diabetogenic)
    • Autis* (to retrieve autism, autistic)
    • Nurs* (to retrieve nurse, nurses, nursing, etc.)
    • Warning! Truncation may also retrieve false hits.  A search on nurs* retrieves  “nursery school”
  • Use the thesaurus function. Click the thesaurus in the upper left hand corner. Type in a keyword. Find similar results. (Note* this is not on every database).

Reference (box taken from):

NYU Libraries. (2020, November 6). Health (nursing, medicine, allied health): Search strategies: Framing the question (PICO). Retrieved from

Background and Foreground Questions: Clinical questions can be categorised as either background or foreground.  Determining the type of question will help you to select the best resource to consult for your answer.

Background questions ask for general knowledge about a condition, test or treatment.  These types of questions typically ask:
who, what, where, when, how, & why about things like a disorder, test, or treatment, or other aspect of healthcare. For example:

  • What are the clinical manifestations of menopause?
  • What causes migraines?

Foreground questions ask for specific knowledge to inform clinical decisions. These questions typically concern a specific patient or particular population. They tend to be more specific and complex than background questions. Quite often, foreground questions investigate comparisons, such as two drugs, or two treatments. For example:

  • Is Crixivan effective in slowing the rate of functional impairment in a 45 year old male patient with Lou Gehrig's Disease?
  • In patients with osteoarthritis of the hip, is water therapy more effective than land-based exercise in restoring range-of-motion?

Reference (box taken from):

University of Canberra Library. (2020, September, 9). Evidence-based practice in health.

Primary Question Types

  • Diagnostic testing:  
    • "How to select and interpret diagnostic tests, in order to confirm or exclude a diagnosis, based on considering their precision, accuracy, acceptability, expense, safety, etc" (Duke University Medical Center & Archives, 2020).
  • Prognosis:
    • "How to estimate a patient's likely clinical course over time due to factors other than interventions" (Duke University Medical Center & Archives, 2020).
  • Therapy:
    • "How to select treatments to offer our patients that do more good than harm and that are worth the efforts and costs of using them" (Duke University Medical Center & Archives, 2020).
  • Harm / Etiology:
    • "How to identify causes for disease (including its iatrogenic forms)" (Duke University Medical Center & Archives, 2020).
  • Prevention
    • "How to reduce the chance of disease by identifying and modifying risk factors and how to diagnose early by screening" (Duke University Medical Center Library, 2005)
  • Cost-Analysis:
    • "How to compare the cost and consequences of different treatments and tests" (Duke University Medical Center Library, 2005).

Additional Question Types

  • Clinical findings:
    • "How to properly gather and interpret findings from the history and physical examination" (Duke University Medical Center & Archives, 2020).
  • Clinical manifestations of disease:
    • "Knowing how often and when a disease causes its clinical manifestations and how to use this knowledge in classifying our patients' illnesses" (Duke University Medical Center & Archives, 2020).
  • Differential diagnosis:
    • "When considering the possible causes of our patient’s clinical problem, how to select those that are likely, serious and responsive to treatment" (Duke University Medical Center & Archives, 2020).
  • Qualitative:
    • "How to empathize with our patients’ situations, appreciate the meaning they find in the experience and >understand how this meaning influences their healing" (Duke University Medical Center & Archives, 2020).


Duke University Medical Center & Archives. (2020, June 25). Evidence-based practice: PICO. Retrieved from

Duke University Medical Center Library. (2005). Evidence-based medicine resources.,to%20all%20of%20the%20patients%20in%20the%20study.

Study Designs


This is a "technique that statistically combines the results of quantitative studies to provide a more precise effect of the results" (Grant & Booth, 2009).

Systematic Review: Meta-Analysis:

A systematic review "seeks to systematically search for, appraise and synthesis research evidence, often adhering to guidelines on the conduct of a review" (Grant & Booth, 2009).

Randomized Controlled Trial: 

"A trial in which participants are randomly assigned to two or more groups: at least one (the experimental group) receiving an intervention that is being tested and another (the comparison or control group) receiving an alternative treatment or placebo. This design allows assessment of the relative effects of interventions" (Dahlgren Memorial Library, 2020).

Controlled Clinical Trial:

"A trial in which participants are assigned to two or more different treatment groups. In Clinical Evidence, we use the term to refer to controlled trials in which treatment is assigned by a method other than random allocation. When the method of allocation is by random selection, the study is referred to as a randomized controlled trial (RCT). Non-randomized controlled trials are more likely to suffer from bias than RCTs" (Dahlgren Memorial Library, 2020).

Cohort/Prospective Studies:

"Cohort studies follow one group that is exposed to an intervention of interest and another group that is non‐exposed to determine the occurrence of the outcome (the relative risk). Cohort studies can examine multiple outcomes of a single exposure" (Lu, 2009). 

Case Control Study: 

A case control study "examines a group of people who have experienced an event (usually an adverse event) and a group of people who have not experienced the same event, and looks at how exposure to suspect (usually noxious) agents differed between the two groups. This type of study design is most useful for trying to ascertain the cause of rare events, such as rare cancers" (Dahlgren Memorial Library, 2020).

Case Series: 

"Analysis of series of people with the disease (there is no comparison group in case series)" (Dahlgren Memorial Library, 2020).

Case Reports:

"Case reports provide anecdotal evidence by describing single cases. Description often includes the manifestations, clinical course, prognosis, how clinicians diagnosed and treated the condition and the clinical outcome" (Lu, 2009).

Prospective, Blind Comparison to a Gold Standard Study:

Prospective, blind comparison to a gold standard studies show "the efficacy of a diagnostic test is called a prospective, blind comparison to a gold standard study. This is a controlled trial that looks at patients with varying degrees of an illness and administers both diagnostic tests -- the test under investigation and the "gold standard" test -- to all of the patients in the study" (Duke University Medical Center Library, 2005).


Dahlgren Memorial Library. (2020, October 27). Evidence-based medicine resource guide. Retrieved from (Dahlgren Memorial Library, 2020).

Duke University Medical Center Library. (2005). Evidence-based medicine resources.,to%20all%20of%20the%20patients%20in%20the%20study

Grant, M. J., & Booth, A. (2009). A typology of reviews: An analysis of 14 review types and associated methodologies. Health Information & Libraries Journal, 26, 91–108.

Lu, C. Y. (2009, April 3). Observational studies: A review of study designs, challenges and strategies to reduce confounding. International Journal of Clinical Practice, 63(5), 691-697. doi:10.1111/j.1742-1241.2009.02056.x

Filtered Information; Scale of Study Design Bias

(Least Biased) Systematic Reviews < Critically-Appraised Topics < Critically-Appraised Individual Articles. (Most Biased(Mentzer, 2020).

Unfiltered Information: Scale of Study Design Bias

(Least BiasedRandomized Control Trial < Cohort Study < Case Control Study < Cross Sectional Study. (Most Biased) (Claude Moore Health Sciences Library, 2020).


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Claude Moore Health Sciences Library. (2020, September 1). Evidence based practice. Retrieved from

Mentzer, K., (2020, October 13). Evidence-based practice for health professionals: Levels of evidence. Retrieved from

Prognosis= Study design of Cohort Study, Case control, Case Series
Therapy: Randomized Control Trial Study design
Etiology or harm=Study design: Randomized control trial cohort study case control case series
Prevention = Study design of Randomized control trial, cohort study, case control, case series
Cost = Study design of economic Analysis