4-Evidence Based Practice (EBP) is a problem-solving approach to clinical decision-making within a health care organization. It integrates the best available scientific evidence with the best available experiential (patient and practitioner) evidence. EBP considers internal and external influences on practice and encourages critical thinking in the judicious application of such evidence to the care of individual patients, a patient population, or a system. The level of evidence are as follows:
Experimental study, randomized controlled trial (RCT)
Systematic review of RCTs, with or without meta-analysis
Systematic review of a combination of RCTs and quasi-experimental, or quasi-experimental studies only, with or without meta-analysis.
Systematic review of a combination of RCTs, quasi-experimental and non-experimental, or non-experimental studies only, with or without meta-analysis.
Qualitative study or systematic review, with or without meta-analysis
Opinion of respected authorities and/or nationally recognized expert committees/consensus panels based on scientific evidence.
– Clinical practice guidelines
– Consensus panels
Based on experiential and non-research evidence.
– Literature reviews
– Quality improvement, program or financial evaluation
– Case reports
– Opinion of nationally recognized expert(s) based on experiential evidence.
According to U.S Department of Health and Human services, Evidence Classification Scheme for a Diagnostic Measure include:
Class I: A prospective study in a broad spectrum of persons with the suspected condition, using a ‘gold standard’ for case definition, where the test is applied in a blinded evaluation, and enabling the assessment of appropriate tests of diagnostic accuracy
Class II: A prospective study of a narrow spectrum of persons with the suspected condition, or a well-designed retrospective study of a broad spectrum of persons with an established condition (by ‘gold standard’) compared to a broad spectrum of controls, where test is applied in a blinded evaluation, and enabling the assessment of appropriate tests of diagnostic accuracy
Class III: Evidence provided by a retrospective study where either person with the established condition or controls are of a narrow spectrum, and where test is applied in a blinded evaluation
Class IV: Any design where test is not applied in blinded evaluation OR evidence provided by expert opinion alone or in descriptive case series (without controls).
Agency for Healthcare Research and Quality. (n.d.). Agency for healthcare research and quality: a profile. Retrieved December 3, 2018, from https://www.ahrq.gov/cpi/about/profile/index.html
Winona State University. (2018). Evidence based practice toolkit. Retrieved December 3, 2018, from https://libguides.winona.edu/ebptoolkit
5-Evidence based medicine uses evidence to make clinical decisions. There is a hierarchal system for classification of evidence. This hierarchy is known as the levels of evidence. Physicians are encouraged to find the highest level of evidence to answer clinical questions (Barnes, Rohrich, & Chung, 2012, p. 305). The higher the level the more strength the evidence has. Randomized controlled trials (RCT’s) are the strongest research designs for treatment or intervention studies because they exert the most control over the methods and the results are considered more trustworthy (Thomas, 2017). It is important to note that a high level of evidence for a treatment study may not be the highest level of evidence for a study for prognosis. The strongest levels of evidence are at the top of the hierarchy. Some examples put concepts into practice from the different levels of evidence that may include practice alerts for revising current policies and instituting new practices.
- Meta-Analysis A systematic review that uses quantitative methods to summarize the results.
- Systematic Review An article in which the authors have systematically searched for, appraised, and summarized all the medical literature for a specific topic.
- Critically Appraised Topic Authors of critically-appraised topics evaluate and synthesize multiple research studies.
- Critically Appraised Articles Authors of critically-appraised individual articles evaluate and synopsize individual research studies.
- Randomized Controlled Trials RCT’s include a randomized group of patients in an experimental group and a control group. These groups are followed up for the variables/outcomes of interest.
- Cohort Study Identifies two groups (cohorts) of patients, one which did receive the exposure of interest, and one which did not, and following these cohorts forward for the outcome of interest.
- Case-Control Study Involves identifying patients who have the outcome of interest (cases) and control patients without the same outcome and looking to see if they had the exposure of interest.
- Background Information / Expert Opinion Handbooks, encyclopedias, and textbooks often provide a good foundation or introduction and often include generalized information about a condition. While background information presents a convenient summary, often it takes about three years for this type of literature to be published.
- Animal Research / Lab Studies Information begins at the bottom of the pyramid: this is where ideas and laboratory
research takes place. Ideas turn into therapies and diagnostic tools, which then are tested with lab models and
Barnes, P. B., Rohrich, R. J., & Chung, K. C. (2012, July 1). The Levels of Evidence and their role in Evidence-Based Medicine. Plastic Reconstructive Surgery, 128(1), 305-310. https://doi.org/doi: [10.1097/PRS.0b013e318219c171]
Thomas, C. J. (2017, May 23). What Does “Levels of Evidence” Mean in Evidence-Based Practice? Nursing Education Expert. Retrieved from https://nursingeducationexpert.com/levels-of-evidence/
6-In attempting to prove the accuracy of a case study or other
investigation, various levels of evidence are utilized in associating well
reputed and accurate sources and data collection methods (Petrisor & Bhandari,
2007). These evaluations grade the overall validity of the study, and help to
show whether or not the evidence is accurate in its findings (Petrisor &
Bhandari, 2007). These levels of evidence are generally seen on seven levels,
with the first being the most valid and the seventh being the least valid. The
first level is gathered through a systematic review of randomized control
trials (RCT), and due to the wide range of its data is the most accurate and
can be used as a basis for broad changes in practice methods (Burns, Rohlich
& Chung, 2011). The second level is gathered through a single RCT that
could be applied to a wide range of practice changes, such as determining intervention
method effectiveness (Darrell W. Krueger Library, 2018). The third level of
evidence is similar to the second, but the participants to groups are not
assigned randomly. This form of evidence can be used in detecting extraneous
variables in a study by examining a particular factor (DWKL, 2018).
level of evidence consists of cohort and case-control studies which compare two
different outcomes between similar studies retrospectively, such as those with
and without a disease to determine outcomes. The fifth and sixth levels relate
to descriptive and non-quantitative studies, with the fifth level examining
numerous studies, and the sixth only examines one (DWKL, 2018). These studies
can be used to describe personal experiences. The final level of evidence is
based off of expert opinions, which are worth exploring for new ideas, but not
scientifically valid (DWKL, 2018).
Burns, P. B., Rohrich, R. J., &
Chung, K. C. (2011). The levels of evidence and their role in
evidence-based medicine. Evidence-based Medicine Toolkit, 128(1),
Darrell W. Krueger Library. (2018, September 18). Evidence based
practice toolkit. Retrieved from
Petrisor, B. A., & Bhandari, M. (2007). The
hierarchy of evidence: Levels and grades of recommendation. Retrieved from