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NURS-692: Evidence Based Practice 1

What is EBP?

Evidence-based medicine (EBM) or evidence based practice (EBP), is the judicious use of the best current evidence in making decisions about the care of the individual patient. EBP also integrates clinical expertise and takes patient desires, values, and needs into consideration. Dr. David Sackett and his colleagues at McMasters University in Ontario, Canada, initially proposed EBM.

EBP is an umbrella term that encompasses evidence-based medicine, evidence-based nursing, evidence-based physical therapy, evidence-based dentistry, etc.

Sackett D. L., Straus S. E., Richardson W. S., et. al.  Evidence-Based Medicine: How to Practice and Teach EBM.  Edinburgh: Churchill Livingstone, 2000.

The Five Steps of EBP

Evidence-based practice consists of five steps:

1. Ask  a searchable clinical question;
2. Find the best evidence to answer the question;
3. Appraise the evidence;
4. Apply the evidence with clinical expertise, taking the patient's wants/needs into consideration;
5. Evaluate the effectiveness and efficiency of the process.

Strauss, S. E.  Evidence-Based Medicine: How to Practice and Teach EBM.  New York: Churchill Livingstone, 2005.

EBP Questions: PICO

PICO is an acronym used to describe the four elements of a compelling clinical research question

P - Population/Problem: How would I describe the problem or a group of patients similar to mine? 

I - Intervention: What main intervention, prognostic factor, or exposure am I considering?

C - Comparison: Is there an alternative to compare with the intervention? 

O - Outcome: What do I hope to accomplish, measure, improve, or affect? 

PICO Question Formats

Fill in the blanks with information from your clinical scenario:


In_______________, what is the effect of ________________on _______________ compared with _________________?

Use: Randomized Controlled Trials (RCTs), meta-analyasis. Also: cohort studies, case-control studies, case series. 



For ___________ does the use of _________________ reduce the future risk of ____________ compared with ______________?

Use: Randomized Controlled Trials (RCTs), meta-analyasis. Also: prospective studies, cohort studies, case-control studies, case series. 



Are (Is) ________________ more accurate in diagnosing _______________ compared with ____________?

Use: Randomized Controlled Trials (RCTs). Also: cohort studies. 



Does ____________ influence ______________ in patients who have _____________?

Use: Cohort studies. Also: case-control studies, case series. 



Are ______________ who have _______________ at ______________ risk for/of ____________ compared with _____________ with/without______________?

Use: Randomized Controlled Trials (RCTs), meta-analyasis, cohort studies. Also: case-control studies, case series. 



How do _______________ diagnosed with _______________ perceive __________________?

Use: Qualitative studies. 

Melnyk, B. M., & Fineout-Overholt, E. (2011). Evidence-based practice in nursing & healthcare: A guide to best practice. Philadelphia: Wolters Kluwer/Lippincott Williams & Wilkins.

Appraising the Evidence

Criteria for Appraisal 

When appraising research, keep the following three criteria in mind:

Quality: Trials that are randomized and double blind, to avoid selection and observer bias, and where we know what happened to most of the subjects in the trial.

Validity: Trials that mimic clinical practice, or could be used in clinical practice, and with outcomes that make sense. For instance, in chronic disorders we want long-term, not short-term trials. We are [also] ... interested in outcomes that are large, useful, and statistically very significant (p < 0.01, a 1 in 100 chance of being wrong).

Size: Trials (or collections of trials) that have large numbers of patients, to avoid being wrong because of the random play of chance. For instance, to be sure that a number needed to treat (NNT) of 2.5 is really between 2 and 3, we need results from about 500 patients. If that NNT is above 5, we need data from thousands of patients.

These are the criteria on which we should judge evidence. For it to be strong evidence, it has to fulfill the requirements of all three criteria.

Levels of Evidence

Rating System for the Hierarchy of Evidence: Quantitative Questions

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

Melnyk, B., & Fineout-Overholt, E. (2011). Evidence-based practice in nursing & healthcare: A guide to best practice (2nd ed.). Philadelphia: Wolters Kluwer/Lippincott Williams & Wilkins, p. 10.

Spalding EBP Guide

To view the full EBP guide, visit: