In this guide you will find Evidence-Based Practice tools, as well as recommended databases, books, practice sites, and information about Evidence-Based Research. Evidence-Based Medicine (EBM) is the integration of clinical expertise, patient values and the best research evidence into the decision making process for patient care.
Clinical expertise refers to the clinician’s cumulated experience, education and clinical skills. The patient brings to the encounter his or her own personal preferences and unique concerns, expectations, and values. The best research evidence is usually found in clinically relevant research that has been conducted using sound methodology. (Sackett D, 2002)
The levels of evidence pyramid provides a way to visualize both the quality of evidence and the amount of evidence available.
For example, systematic reviews are at the top of the pyramid, meaning they are both the highest level of evidence and the least common.
As you go down the pyramid, the amount of evidence will increase as the quality of the evidence decreases.
Studies are assigned levels of evidence based on their methodology. The evidence pyramid is an easy way to visualize this hierarchy of evidence.
At the top of the pyramid is filtered evidence including systematic reviews, meta-analyses, and critical appraisals. These studies evaluate and synthesize the literature. The top of the pyramid represents the strongest evidence.
At the base of the pyramid is unfiltered evidence including randomized controlled trials, cohort studies and case reports. These are individual reports and studies, also known as the primary literature.
You should seek the highest level of evidence available, but remember that evidence at the top of the pyramid might not exist for your particular clinical question. If that is the case, you'll need to move down the pyramid to find the strongest evidence that addresses your clinical question.
Evidence Rating |
Evaluation Criteria |
Level I
|
Evidence from a Systematic Review or Meta-Analysis of all relevant Randomized Controlled Trials (RCTs) or evidence based Clinical Practice Guidelines based on systematic reviews of RCTs |
Level II |
Evidence obtained from at least one well-designed RCT |
Level III |
Evidence obtained from well-designed Controlled Trials without Randomization |
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 |
From: Melnyk, Bernadette Mazurek, and Ellen Fineout-Overholt. Evidence-Based Practice in Nursing & Healthcare: A Guide to Best Practice
Image source: Georgetown University Medical Centre
Research Generate Evidence to Improve Practice