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Evidence Based Practice

This guide highlights principles and resources used in Evidence Based Practice for both medicine and nursing.

Why EBP?

"Unfortunately, there is a large though variable gap between what we know from research and what we do in clinical practice.  Because so much research is published - some valid and some invalid - clinicians understandably are unaware of most of it, or do not have the 'tools' to assess its quality.  Researchers, on the other hand, may not understand the information needs of clinicians and often present their work in a way that is not easily accessible to busy practitioners.  In 1972, British epidemiologist Archie Cochrane highlighted the fact that most treament-related decisions were not based on a systematic review of clinical research.  Rather, they were based on an ad hoc selection of information from the vast and variable quality scientific literature, on expert opinion or, worst of all, on trial and error."

Excerpt from Evidence-Based Practice Workbook, 2nd ed. by Paul Glasziou, Chris Del Mar and Janet Salisbury.  Blackwell, 2007.

EBP Research Process

  1. Convert information needs into focused questions:
    • You may wish to use the PICO model (linked below) to define a clear clinical question that incorporates the Patient/problem, Intervention,Comparison, and Outcome.
  1. Efficiently track down the best evidence with which to answer the question:
    • Select a database in which to start (see our recommended list of EBP databases, linked below)
    • After searching, refine your results as needed using limiters. As shown in the pyramid of evidence to the left, certain types of literature are considered most useful in answering clinical questions. Many databases allow you to limit results by study type.
  1. Critically appraise the evidence for validity and clinical usefulness.
  2. Apply the results in clinical practice.
  3. Evaluate performance of the evidence in clinical application.

 *Adapted from UIC University Library's Evidence Based Medicine research guide.

Types of Evidence

Pyramid of Evidence

Pyramid of Evidence. Source: “EBM Pyramid.” Digital Image. Eli M. Oboler Library, 27 May 2016.

Source: “EBM Pyramid.” Digital Image. Eli M. Oboler Library, 27 May 2016.


Filtered Information (secondary literature)

Systematic review
Uses explicit, rigorous methods to identify, critically appraise, and synthesize relevant studies

Meta analysis
A quantitative method of combining the results of independent studies and synthesizing summaries and conclusions which may be used to evaluate therapeutic effectiveness.

Critically Appraised Topic
A summary of the current best evidence on a topic, generally by topic experts. Critically appraised topics (CAT's) usually include evidence from more than one study, but are more brief and their methods less rigorous than systematic reviews.

Critically Appraised Individual Article (a.k.a. Critically Appraised Paper)
A summary of a single paper, generally by a topic expert.


Unfiltered Information (primary literature)

Randomized controlled trial
A clinical trial that involves at least one test treatment and one control treatment, concurrent enrollment and follow up of the test- and control-treated groups, and in which the treatments to be administered are selected by a random process

Cohort study
Study in which subsets of a defined population are identified.

Case control trial
Study which start with the identification of persons with a disease of interest and a control group without the disease. The relationship of an attribute to the disease is examined by comparing diseased and non-diseased persons with regard to the frequency or levels of the attribute in each group.

Clinical trial
Pre-planned studies of the safety, efficacy or optimum dosage schedule of one or more diagnostic, therapeutic or prophylactic drugs, devices or techniques, selected according to predetermined criteria of eligibility and observed for predefined evidence of favorable and unfavorable effects.

Evidence Based Practice Overview

EBP and EBN Definitions

1) "Sigma Theta Tau defines EBN as an integration of the best evidence available, nursing expertise, and the values and preferences of the individuals, families, and communities who are served.  This assumes that optimal nursing care is provided when nurses and health care decision-makers have access to a synthesis of the latest research, with a consensus of expert opinion. They are thus able to exercise their judgement as they plan and provide care that takes into account cultural and personal values and preferences (Sigma Theta Tau International 2003)."

Evidence-based nursing: Rationale and resources. Worldviews Evid Based Nurs. 2004;1(1):69-75.

2) "The systematic interconnecting of scientifically generated evidence with the tacit knowledge of the expert practitioner to achieve a change in a particular practice for the benefit of a well defined client/patient group."

French P. The development of evidence-based nursing. J Adv Nurs. 1999;29(1):72-78.

3) "EBN could be defined as ‘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.’ This proposed definition of EBN indicates the use of evidence, theory and expertise in making decisions about optimum care for and with the individual patient."

Scott K, McSherry R. Evidence-based nursing: Clarifying the concepts for nurses in practice. J Clin Nurs. 2009;18(8):1085-1095.

4) “Evidence-based nursing is a process by which nurses make clinical decisions using the best available research evidence, their clinical expertise and patient preferences, in the context of available resources."

Thompson C. Clinical experience as evidence in evidence-based practice. J Adv Nurs. 2003;43(3):230-237.

EBP Medical Student Users Guide

Evidence-Based Practice: Rush University Medical Center Medical Student Users' Guide

Prepared by the Rush University Medical Center Evidence-Based Practice Interest Group (May 7, 2012)

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