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Nursing Subject Guide: Evidence Based Nursing & PICO Research

This page is based on the work of Karen Delorey, Mass Bay Community College.

Step One: Develop a PICO Question

Using the PICO format can be instructive!

Patient Population
Comparison Intervention

Types of Questions: Etiology, Diagnostic, Prevention, Prognosis/Prediction, Therapy, Qualitative

Prevention Example:
For patients with systolic heart failure (P) do exercise programs (I) reduce the future risk of hospital admission due to heart failure (O) compared with patients without exercise programs (C)?
Therapy Example:
In patients with chronic wounds (P) what is the effect of topical negative pressure (TNP) (I) on promoting healing (O) compared with traditional moisturized gauze (C) dressing?

Steps Two through Five

Step Two: Acquire the most relevant, most current, best evidence. See Evidence Hierarchy

Step Three: Appraise the evidence.

Step Four: Apply all evidence with clincial experience, patient preferences and values in making a practice decision or change.

Step FiveAccess the practice decision or change.

PICO Continued (Examples)

Etiology: Are ____(P), who have ____ (I) at ____(increased/decreased)risk for/of_____(O) compared with____(P) with/without_____(C)?

Diagnostic: Are(Is)____(I) done on _____(P)more accurate in diagnosis of _____(O)compared to ______(C)?

Qualitative: How do ____ (P), perceive the  ____ (I) on ____ (O) compared to _____ (C)?

Prognosis/Prediction: Does ____ (I) influence ____ (O) in patients who have ____ (P)?

TRIP Database PICO Wizard:
You may find this helpful.  Click on the PICO Search button for help building a PICO question.

What is Evidence Based Practice?

EBP is a method of effectively translating EBM into clinical practice using the best existing: evidence and research, knowledge of clinical experts, and patient preferences.

Evidence Pyramid

This Evidence Hierarchy Pyramid is often used to graphically represent the quality of medical research. The higher on the pyramid the more comprehensive in scope, and more rigorous the methodology and peer review. You should be looking for the highest level of research available in EBP.

This guide will help you locate the highest levels of evidence: systematic reviews & meta-analyses, and practice guidelines. 

If you can't locate the highest levels of research to answer a specific clinical question you should use the highest level available.  Look for tutorials on searching reliable sources such as CINAHL, Medline, and PubMed databases for articles, studies and reports.


Systematic Review: A systematic review  tries to identify, appraise, select and synthesize all RCTs (randomized control trials) relevant to a specific clinical question.  Stringent guidelines are set in order to draw a conclusion about whether or not there is conclusive evidence about a specfic treatment or topic.

Randomized Control Trial: An RCT is a clinical trial in which the subjects are randomly distributed into groups that are either subjected to the experimental procedure (such as use of a drug) or that serve as controls.  It is the research design considered to provide the most reliable evidence for evaluating the effectiveness of an intervention.

Meta-Analysis: A meta-analysis is a review that combines the quantitative (numbers) results from different studies on a defined intervention in order to obtain a quantitative estimate of the overall effect of the particular intervention.  A meta-analysis produces a stronger conclusion than can be provided by any individual study.

Practice Guideline: Clinical Practice Guidelines are practice recommendations based on rigorous review of the best evidence on a specific topic.

Cohort Study: A study designed to determine the relationship between a condition and a characteristic shared by some members of a group. The population selected is healthy at the beginning of the study. Some of the members of the group share a particular characteristic, such as cigarette smoking. The researcher follows the population group over a period of time, noting the rate at which a condition, such as lung cancer, occurs in the smokers and in the nonsmokers.

Case Control Study: A study where previously existing incidents of a medical condition are used in lieu of gathering new information. A group of patients with a particular disease or disorder, such as myocardial infarction, is compared with a control group of persons who have not had that medical problem. The two groups, matched for age, sex, and other personal data, are examined to determine which possible factor (e.g., cigarette smoking, coffee drinking) may account for the increased disease incidence in the case group.

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