What is Evidence Based Practice?
Evidence-Based Practice (EBP): Evidence-based practice is the judicious use of the best research evidence (found in health sciences literature), clinical expertise (what the health care provider knows) and patient values (what the patient wants and believes) to create a plan of action regarding patient care. Evidence-based practice is an umbrella term that covers evidence-based medicine, evidence-based dentistry, evidence-based public health, evidence-based nursing and etc.
The Steps in the EBP Process:
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ASSESS |
1. Start with the patient -- a clinical problem or question arises from the care of the patient |
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ASK |
2. Construct a well built clinical question derived from the case |
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ACQUIRE |
3. Select the appropriate resource(s) and conduct a search |
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APPRAISE |
4. Appraise that evidence for its validity (closeness to the truth) and applicability (usefulness in clinical practice) |
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APPLY: |
5. Return to the patient -- integrate that evidence with clinical expertise, patient preferences and apply it to practice |
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Self-evaluation |
6. Evaluate your performance with this patient |
About the Hierarchy of Evidence
ebooks
Johns Hopkins Evidence-Based Practice for Nurses and Healthcare Professionals, Fourth Edition by Levels of Evidence
As you move up the pyramid the study designs are more rigorous and allow for less bias or systematic error that may distract you from the truth.
Study Types/Designs
Case Report - a write up of the case of an individual patient; a clinical presentation. Often the first report of a new disease or disease trend.
Case Series - a write up of the cases of several patients all undergoing similar treatment.
Case-Control Study - a comparison of study subjects with a particular disease/risk factor (cases) to those without (controls). These have also been called retrospective studies. A good design for rare diseases but easy to get poor data.
Clinical Trial - an experimental study in which subjects receive an intervention. Preferably subjects are assigned to either treatment or no treatment/placebo (see Controlled Clinical Trial). Some trials compare multiple treatments, e.g. the subjects could be assigned to: Treatment A, Treatment B, No treatment/placebo. The different groups are called arms. This is the best study design for testing effect of interventions.
Cohort Study - a group of subjects followed through time. Cohort studies can be used to track effect of an exposure, e.g. all subjects had been exposed to lead in their housing, or they can track a cohort not exposed. They have also been called prospective studies. This is a strong design for determining risk and incidence.
Controlled Clinical Trial - a Clinical Trial where there is a control group receiving a comparison treatment or no treatment/placebo.
Cross Sectional Study - a descriptive study that documents the number of people with a particular disease or risk factor.
Randomized Controlled Trial - Same as Controlled Clinical Trial, with the added benefit of the subjects being randomly assigned to treatment/no treatment arms. This avoids selection bias as all subjects have an equal chance of being assigned to any one of the treatment/no treatment arms. Random assignment can be accomplished using machine generated random number tables. Assigning subjects using methods such as coin tosses or assigning even-odd numbers is considered pseudo-randomization.
Review Articles
Review articles are not considered evidence. One exception to this are Systematic Reviews - including their subset, Meta-Analysis.
Why are Systematic Reviews included in the evidence based pantheon? They aim for documented, exhaustive and comprehensive searching for all research on a specified topic. Most other types of reviews either do not document their search and collection of the research nor do they verify that they have completed an exhaustive and comprehensive search.
All Things Random
In evidence based practice, much is made of Randomized Control Trials (i.e. clinical trials where participants are randomized assigned to an interventions, including a control group.) Why? Randomized Control Trials - RCTs - can show cause and effect not just association.
However, they are not the only study design available. This page provides a glossary (left column) of some of them. For more info & a nifty chart, check out CEBM's Study Design site.
Making sense of it all
Study designs can be classified as descriptive or analytical. The analytical studies have more power, or ability to predict, than descriptive studies and therefore rank higher in the evidence based world.
Descriptive studies give us a snap shot of what is happening. Surveys, case reports, cross sectional studies (using surveys) are descriptive. They cannot show cause and effect, but they can show prevalence or incidence. They can also be useful in spotting trends.
Analytical studies measure the relationship between factors. Cohort studies and randomized control trials are analytical. They show cause and effect.
Understanding Levels of Evidence