According the the American Association of Colleges of Nursing, evidence-based practice (EBP) is:
See the "Finding EBP resources" page of this tab to begin searching for EBP resources.
Levels of evidence (sometimes called hierarchy of evidence) are assigned to studies based on the methodological quality of their design, validity, and applicability to patient care. These decisions gives the grade (or strength) of recommendation.
Level of evidence | Article type/s |
---|---|
Level 1 | Systematic review & meta-analysis of randomized controlled trials; clinical guidelines based on systematic reviews or meta-analyses (filtered, secondary) |
Level 2 | One or more randomized controlled trials (unfiltered, primary) |
Level 3 | Controlled trial (no randomization; unfiltered, primary): |
Level 4 | Case-control or cohort study (unfiltered, primary) |
Level 5 | Systematic review of descriptive & qualitative studies (filtered, secondary) |
Level 6 | Single descriptive or qualitative study (unfiltered, primary) |
Level 7 | Expert opinion |
Adapted from: Melnyk, B.M. & Fineout-Overholt, E. (2011). Evidence-based practice in nursing and healthcare: A guide to best practice. Philadelphia: Lippincott, Williams & Wilkins.
As unfiltered or primary literature begins to circulate, others who were usually not involved in the original research, provide analysis, interpretation, and often synthesis of the primary literature, either of individual studies or groups of them. This is the secondary, or filtered literature. It can take the form of review articles, systematic reviews, meta-analyses, evidence summaries, or guidelines.
The reporting and dissemination of scientific research follows a cycle. Reports of new, original research written by the scientists who conducted it are sometimes referred to as primary, or unfiltered literature. These first-hand accounts can take the form of journal articles, conference proceedings, dissertations, technical reports, or more informal online communications.
Regardless of what type of literature you're consulting, be critical! (See the Evaluating sources subpage under the "Appropriate?" tab above for more information).
Empirical research articles are reports of original scientific research, written by the scientists themselves. They can be identified by having some or all of the following characteristics:
These are unfiltered or primary resources. These can be levels 2-4 or 6 depending on the methods used.
Literature reviews are meant to analyze and pull together – in one place -- the results of different research projects on a specific topic. They are usually written by a scholar/practitioner in the field, but not necessarily by someone who has done empirical research themselves. Literature review articles can be identified by having some or all of the following characteristics:
These are filtered or secondary resources. These are level 7, as the literature is typically reviewed in a nonsystematic, idiosyncratic way and conclusions can be more opinion based rather than evidence based.
Systematic reviews are literature reviews focused on a single question that try to identify, appraise, select and synthesize all high quality research evidence relevant to that question.
These are filtered or secondary resources. These are level 1, unless focusing on descriptive or qualitative studies (in which case they are level 5)
Meta-analyses are systematic reviews that combine the results of several studies (often clinical trials) using quantitative statistics. They may be used to evaluate therapeutic effectiveness, plan new studies, etc.
These are filtered or secondary resources. These are level 1.
Clinical practice guidelines are systematically developed statements of appropriate care designed to assist the practitioner and patient make decisions about appropriate health care for specific clinical circumstances.
These are filtered or secondary resources. These are level 1.
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