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Evidence-Based Practice & PICO: Home

A guide for locating nursing information resources for nursing education, practice and research.

Evidence-Based Practice

What is Evidence-Based Practice?

Evidence-Based Nursing is, “an ongoing process by which evidence, nursing theory and the practitioners’ clinical expertise are critically evaluated and considered, in conjunction with patient involvement, to provide delivery of optimum nursing care for the individual . 

EBN is an approach to practice that is intended to improve the safety and effectiveness of nursing care and practices.

EBP graphic illustration

The 5 Steps of EBP

Evidence-based practice consists of five steps:

ASSESS the patient

ASK a searchable clinical question

ACQUIRE the best evidence to answer the question

APPRAISE the evidence

APPLY to the patient

Also consider the type of question you are asking and determine what study type might be most relevant. 

Most Clinical Questions:  
Meta-Analyses, systematic reviews
Randomized Controlled Trial
Diagnosis:  Prospective, blind controlled trial compared to gold standard
Prognosis:  Cohort study, case control, case series/case report

Recommended list of Nursing Journals to support nursing students in developing the knowledge and skills they need to implement EBP consistently, one step at a time.

American Journal of Nursing                                           

American Nurse Today

Nursing Made Incredibly Easy


Medsurg Nursing

Some other U.S. Nursing Journals which often have articles written by nurses in the field of medicine:

Journal for Nurse Practitioners

Critical Care Nursing Clinics of North America

Nursing Clinics of North America



Identify the problem

The most important step in Evidence-Based Nursing (EBN) is to correctly identify a problem through patient assessment or practice assessment, processes that require reflection by the nurse on clinical practice, in conjunction with a knowledge of the patient's present circumstances.  The information below describes how to frame the question once the patient or practice assessment and the resulting problem identification have occurred.

Background vs. Foreground

Background questions ask for general knowledge and do not normally arise from the need to make a clinical decision.

  • Background questions usually have two essential components:
    • A question root (who, what, when, etc.) with a verb
    • A disorder, treatment, test, or other aspect of healthcare
      • e.g. What causes obesity? When should children be introduced to sexual education?  Who is most susceptible to nursing burn out?
  • Background information can be found in: 
    • reference book entries
    • textbooks, chapters, appendices
    • drug monographs, guides to diagnostic tests

Foreground questions ask for specific knowledge to inform clinical decisions or actions.

  • ​Foreground questions usually have 3 or 4 essential components, from the PICO format:
    • ​Patient/population characteristics, problem
    • Interventions or Exposures 
    • Comparison
    • Outcome

Types of Questions

Clinical questions

Clinical questions typically fall into one of four main categories:

  • Etiology (or harm/risk factors): What causes the problem?
  • Diagnosis: Does this patient have this problem?
  • Therapy: What is the best treatment for this problem?
  • Prognosis: What will the outcome of the problem be?

* Knowing the type of clinical question is important later in the EBN process--once the nurse goes to look for studies that will answer his/her question.

Nursing Practice Questions

In nursing, many other questions about practice will also arise, with some of the questions resulting from the nursing principle of working with rather than on the patient. These questions can be quantitative or qualitative in nature. Examples include:

  • What other, validated instruments for measuring this condition or phenomenon (e.g. pain) exist and how do they compare to the one we currently use? 
  • Should a nurse deliver patient education on the patient's disease/condition near the beginning or the end of an appointment or consultation?
  • How do caregivers of patients with [x] cope with the burden of care and how can nurses assess the level of caregiver burden and/or support the caregivers?

Clinical and nursing practice questions can be broken down into the PICO(T) format, which breaks a question apart into searchable parts:

P – Patient, population, problem
I – Intervention or Exposure
C – Comparison 
O – Outcome 
T – Time (optional)

Example: A small, rural hospital's primary population has become elderly patients and the nurses are working together to update patient safety procedures. When they look at hospital records, they realize that falls are their number one risk factor among their patients. The question might be: what is the effectiveness of restraints in reducing the occurrence of falls in patients 65 and over? , which can be broken apart into descriptors, written in noun forms, such as:

  • P – elderly, inpatient, accidental falls
  • I – restraint, physical restraint
  • C – no restraint
  • O – to be determined once the literature has been found and in conjunction with an understanding of the patient’s specific situation and the underlying causes of sleep loss.
  • T--not applicable in this example

A worksheet to assist you in breaking your question apart using PICO can be found here: 


The following examples may help you put PICO into practice.  Suggestions in the brackets are just extra ideas for what you might want to consider.

1) Isobel is a 45 year old woman who asks you for advice on natural ways of resolving her depression.  She's particularly interested in whether she'd gain any benefits to her mental health from exercising.

P - 40 plus year old woman with depression (but also ask whether you need to know the severity of her depression, and whether she has any other health conditions that may suffer or benefit from exercise)

I - Exercise (but what type and how strenuous?)

C - Antidepressants (what strength and for how long?)

O - Reduced or eradicated depression.

So your question might be:

  • How does the use of exercise compare to medication in treating depression in middle-aged women?

2) Fred is 72, and is undertaking therapy for recovery from a stroke which affected his mobility.  His daughter is a strong advocate of acupuncture, and has suggested he ask about it at his next appointment with you.

P - Men in their 70s who have suffered from stroke

I - Acupuncture (but duration, frequency etc?)

C - Fred's current therapy

O - Higher recovery rate (in terms of time of recovery and level of improvement to mobility)

So your question could be:

  • How effective is accupunture in improving mobility in elderly male stroke patients in comparison to standard stroke therapy?

Your questions might not match these exactly, but they should contain all the elements from your PICO answers, and your choice of comparison and outcome will modify your question somewhat.  For example, you might modify your question to include specific brands/types of therapy such as light jogging versus a specific drug in the depression scenario.

Using PICO to aid searching

Once you've attributed each element of your scenario to PICO, you can then start to look at formulating a list of synonyms to use in searching.

Using the depression and exercise example above, we could look at it like this (we are sure you can think of many more alternative terms though!):

PICO answer Synonym 1 Synonym 2
40 year old woman middle aged woman middle aged female
Exercise physical therapy physical exertion
Antidepressants [name of antidepressant]    medication
Reduced depression    treatment of depression   management of depression

Levels of Evidence

Levels of evidence are assigned to studies based on the methodological quality of their design, validity, and applicability to patient care. The combination of these attributes gives the level of evidence for a study.  In nursing, the system for assigning levels of evidence is often from Melnyk & Fineout-Overholt's 2011 book, Evidence-based Practice in Nursing and Healthcare: A Guide to Best Practice.  The Levels of Evidence below are adapted from Melnyk & Fineout-Overholt's (2011) model. 

Levels of Evidence chart: Level I: Evidence from a systematic review of all relevant randomized controlled trials (RCT's), or evidence-based clinical practice guidelines based on systematic reviews of RCT's. Level II: Evidence obtained from at least one well-designed Randomized Controlled Trial (RCT). Level III: Evidence obtained from well-designed controlled trials without randomization, quasi-experimental. Level IV: Evidence from well-designed case-control and cohort studies. Level V: Evidence from systematic reviews of descriptive and qualitative studies. Level VI: Evidence from a single descriptive or qualitative study. Level VII: Evidence from the opinion of authorities and/or reports of expert committees

About Levels of Evidence and the Hierarchy of Evidence: While Levels of Evidence correlate roughly with the hierarchy of evidence (discussed elsewhere on this page), levels of evidence don't always match the categories from the Hierarchy of Evidence, reflecting the fact that study design alone doesn't guarantee good evidence. 

About Levels of Evidence and Strength of Recommendation: The fact that a study is located lower on the Hierarchy of Evidence does not necessarily mean that the strength of recommendation made from that and other studies is low--if evidence is consistent across studies on a topic and/or very compelling, strong recommendations can be made from evidence found in studies with lower levels of evidence, and study types located at the bottom of the Hierarchy of Evidence. In other words, strong recommendations can be made from lower levels of evidence.

For example: a case series observed in 1961 in which two physicians who noted a high incidence (approximately 20%) of children born with birth defects to mothers taking thalidomide resulted in very strong recommendations against the prescription and eventually, manufacture and marketing of thalidomide. In other words, as a result of the case series, a strong recommendation was made from a study that was in one of the lowest positions on the hierarchy of evidence.

Hierarchy of Evidence: Qualitative and Quantitative

Quantitative Evidence Pyramid

Tip of Pyramid = MetaAnalysis; next level=Systematic Review; third level=Critically Appraised Topics; 4th level=Critically Appraised Individual Articles; 5th level=Randomized Controlled Trials; 6th level=Cohort Studies; 7th level=Case-Controlled studies or reports; bottom level=background information or expert opinion

Qualitative Evidence Pyramid

Tip of pyramid=Generalizable Studies (divers sample population); 2nd level=Conceptual Studies (based on a single theoretical framework); 3rd level=descriptive studies (sample of a narrowly defined population to illustrate practical issues); bottom level=single case study

Know the Difference! Systematic Review vs. Literature Review

It is common to confuse systematic and literature reviews as both are used to provide a summary of the existent literature or research on a specific topic.  Even with this common ground, both types vary significantly.  Please review the following chart (and its corresponding poster linked below) for the detailed explanation of each as well as the differences between each type of review.

Systematic vs. Literature Review
  Systematic Review Literature Review
Definition High-level overview of primary research on a focused question that identifies, selects, synthesizes, and appraises all high quality research evidence relevant to that question Qualitatively summarizes evidence on a topic using informal or subjective methods to collect and interpret studies
Goals Answers a focused clinical question
Eliminate bias
Provide summary or overview of topic
Question Clearly defined and answerable clinical question
Recommend using PICO as a guide
Can be a general topic or a specific question
Components Pre-specified eligibility criteria
Systematic search strategy
Assessment of the validity of findings
Interpretation and presentation of results
Reference list
Reference list
Number of Authors Three or more One or more
Timeline Months to years
Average eighteen months
Weeks to months
Requirement Thorough knowledge of topic
Perform searches of all relevant databases
Statistical analysis resources (for meta-analysis)

Understanding of topic
Perform searches of one or more databases

Value Connects practicing clinicians to high quality evidence
Supports evidence-based practice
Provides summary of literature on the topic

Why Do I Need Journals and Databases?

  • Many people believe that everything is now available on the Web, for free to everyone. This just isn't so.
  • The credibility of health information on the Web can be questionable.
  • Searching the web through general search engines like Google and Bing can be overwhelming and time consuming.

As professionals you will want to use bibliographic databases such as CINAHL and PubMed (MEDLINE) to keep current with the research literature. In addition, full text databases such as the Cochrane Library (a database of systematic reviews), textbook resources such as STAT!Ref, and electronic journals such as Evidence Based Nursing can provide needed information, quickly and easily.

How the Library Can Help

While some web-based resources are free, many quality resources, such as the indexes, databases, journals, and textbooks that you need to do your job have a cost associated with them. Libraries provide access to many online resources, by paying subscription fees to publishers and vendors with the understanding that their library users can access this information from within the library, on campus, and sometimes from off-campus computers as well through proxy access.


What is a Database?

A bibliographic database leads the user to sources of information, usually in journals, providing a citation that includes the article's author, title and source information; journal name, volume, issue and page numbers, and often an abstract of the article. As opposed to the Cochrane systematic review databases, the searcher must analyze the quality and relevance of the studies themselves when using PubMed and CINAHL.


Here are the two of the most utilized databases by nurses:


The CINAHL database (Cumulative Index to Nursing and Allied Health) covers nursing, allied health, biomedical and consumer health journals, publications of the American Nursing Association, and the National League for Nursing. Over 350,000 records and 900 journals are included. It also includes healthcare books, nursing dissertations, standards of professional practice, nurse practice acts, and educational software.

  • PubMed

PubMed (MEDLINE) is a free resource provided by the National Library of Medicine. Anyone can access this database, which is widely recognized as the premier source for bibliographic and abstract coverage of biomedical literature.

PubMed includes citation and abstract information from Index Medicus, Index to Dental Literature, and International Nursing Index, as well as other sources in the areas of allied health, physical therapy, health education, biological and physical sciences, humanities and information science as they relate to medicine and health care, communication disorders, population biology, and reproductive biology.