research guides: nursing research: writing and citing: evidence based practice

levels of evidence

the research pyramid

the gold standard of evidence is a the systematic review: an article which examines, appraises and consolidates findings of all of the primary research for a medical question.

in the middle section, clinical research constitutes content that is vetted and verified such as clinically appraised topics and clinically appraised articles.

foundational research is at the bottom of the pyramid and include unfiltered and/or unverified sources, such as single studies.

the bottom level of information in medical practice is opinion and background information. the kind of information that may be found in a textbook or encyclopedia.

sources on the chart to the left give tips on how to retrieve specific levels of evidence from journal databases.

dictionary of evidence based medicine terms center for evidence based medicine

searching for levels of evidence

systematic reviews	health evidence.org. is a free index of systematic reviews from 1995 on in public health. registration required. search the database of abstracts of reviews (dare) subset in the ebm/cochrane database pubmed clinical queries search or conduct a search from the main screen and filter by article type cinahl (filter by publication type)
clinically appraised topics	ngc national guideline clearinghouse evidence based clinical practice guidelines. (us) updated weekly.
clinically appraised individual articles	the acp journal club can be accessed in print. it is also a subset of the ebm/cochrane database. evidence based nursing (print journal)
searching multiple types of filtered ebm information	the trip database in cinahl you may filter by multiple publication types such as case study, clinical trial, randomized control trial, research, systematic review)
randomized controlled trials	the cochrane central register of controlled trials is a subset of the ebm cochrane database pubmed – filter by article type after searching options for clinical trial, randomized control trial etc. cinahl – use the filter on the advanced search screen
cohort studies	there is no filer. in pubmed add the mesh subject cohort studies. in cinahl use the subject prospective studies
case controlled studies/case series reports	in cinahl refer to the subject heading case controlled studies

background information

for encyclopedias and reference sources see the reference sources section of this guide. northern ontario school of medicine may also be accessed. see instructions.