CUNY SPS: Nursing - A Research Guide for SPS Students

Evidence Based Medicine (EBM)

Evidence-based medicine is the "conscientious, explicit and judicious use of current best evidence in making decisions about the care of individual patients"
(Sackett, D. L., Rosenberg, W. M., Gray, J. A., Haynes, R. B., & Richardson, W. S. (1996). Evidence based medicine: what it is and what it isn't. BMJ (Clinical research ed.), 312(7023), 71-2. ).

Literature Searches Form Core Steps in the EBM Process                 


  • ASSESS the patient
  • ASK an searchable, well-built clinical question
  • ACQUIRE (search for) evidence in the healthcare literature
  • APPRAISE evidence results for validity and acceptability
  • APPLY evidence to patient care
  • EVALUATE the whole process
4As Evidence Based Medicine
  University of Wisconsin Ebling Library, Intro to EBM

1.1 ASK: Identify the Question

A good question:

  • focuses what information you need
  • identifies key search concepts
  • points you  in the direction of potential resources

[cited from Forming Questions in Nursing LibGuide, McMaster University by Laura Banfield]

Is your clinical question a background or a foreground question?

Clinical foreground questions are at the heart of Evidence-Based Medicine. A useful framework to develop your foreground question is to plug in four question components, known by the acronym, PICO. PICO stands for:  P=Patient/Population/Problem; I = Intervention or exposure; C=Comparison; O=Outcome.

Next, determine what type of PICO question you wish to ask by identifying its underlying objective. The objective of most PICO questions falls into one of these categories or domains: therapy; diagnosis; prevention; prognosis; harm/etiology. The domain type will provide a structure to format your question and focus your search.

1.2 ASK: Hone your search strategy

1. To conduct an effective search, use your PICO question to:

  • figure out what are your key search terms:

Finding the Evidence 1 video tutorial (CEBM)

  • and structure your search strategy:

Turning search terms into a search strategy video tutorial (CEBM)

2. Focus on which research methods and study designs to include. Different research methodologies are better suited to answer different kinds of questions.

For more information about study design, see this CEBM webpage.

2.1 ACQUIRE evidence: select resources

Evidence Pyramid

EBM Pyramid

University of Wisconsin, Ebling Library, EBM Guide

This evidence pyramid graphically depicts the study design types in the medical literature relative to the strength of their evidence. The higher the layer on the pyramid, the greater the strength of the evidence in the study type. 

Using your clinical question and search strategy worked out in the prior steps, "Start at the Top of the Evidence Pyramid and Work Down (Database Search Tips, VCU)."  The study types in the higher levels yield a smaller volume of research relative to those in the lower layers. If your search results at the higher levels are too few,  search again targeting a study type from a suitable lower layer.

For more guidance, see this handout.

2.2 ACQUIRE evidence: search the databases

Start your database search broad, then focus:

if there are too many results,  use limits/filters of the database (Publication/Study Types, Gender/Sex, Language, Etc)

If there are too few results, add an additional concept or term

(cited from Database Search Tips, VCU Nursing Research Guide by Roy Brown)

Relevant Databases to Search

For Meta analyses and systematic reviews, search in:

For Randomized Control Trials, Cohort Studies, Case Control Studies, search in:

3. APPRAISE the evidence in search results

Helpful EBM Resources Online

Evidence-Based Medicine (EBM) Resources

Evidence-Based Medicine Tutorials

Introduction to Evidence-Based Medicine

From Duke University Medical Center Library and University of North Carolina at Chapel Hill Health Sciences Library.

Evidence Based Nursing Tutorial

From the University of Illinois at Chicago

Evidence-Based Practice Toolkit for Nursing

From Ohio State University Libraries

Nursing Evidence Based Practice Resources

From Virginia Commonwealth University

Evidence-Based Medicine Information Sites

Centre for Evidence-Based Medicine (Oxford University)

The Centre promotes evidence-based health care and provide support and resources to anyone who wants to make use of them. Includes the EBM Toolbox, an assortment of materials which are very useful for practitioners of EBM, and EBM Teaching Materials, including PowerPoint presentations.

Evidence-Based Medicine

A reference guide on Evidence-based practice including a selective list of additional EBM websites developed and maintained by Duke University Medical Center Library.

Students for Best Evidence

A network for students interested in evidence-based health care.

Ask for Evidence

A UK based site