Relative Citation Impact of Various Study Designs in the Health Sciences
Top Cited Papers
Open Access
- 18 May 2005
- journal article
- research article
- Published by American Medical Association (AMA) in JAMA
- Vol. 293 (19) , 2362-2366
- https://doi.org/10.1001/jama.293.19.2362
Abstract
Several authors and organizations have proposed hierarchies of evidence, based on the relative reliability of various types of study designs.1-4 Although many people recognize that expert opinions and nonsystematic reviews provide the least reliable level of information,5,6 such articles continue to have a massive influential presence.7 Controlled studies assume higher places in hierarchies of evidence than uncontrolled studies, and randomized trials are considered the gold standard for clinical research.1-4 However, randomized trials cannot be conducted for all questions of interest8 and there is debate on whether they give different results than nonrandomized studies.9-14 Finally, meta-analyses are becoming increasingly frequent in the literature. Meta-analyses are often placed at the highest level of evidence,1-4 despite their critics.15,16 No hierarchy of evidence is unanimously accepted.Keywords
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