I am currently in a DNP program and one of our assignments was to complete a literature search on a topic. As I began my search through Ovid, ProQuest, EBSCO, Cochrane Library of Systematic Reviews, and other databases, I began to realize how easy it would be to become overwhelmed by the multitude of articles and studies published on the topic. I quickly became aware that not all information labeled as "evidence-based" was truly evidence-based. How many times do we see an original research article published in a peer-reviewed journal and the media begins making statements that there should be a change in healthcare practice. As healthcare professionals, we recognize that one original study is not sufficient to change practice. There is a hierarchy to evidence that all healthcare providers should be aware of. I have found two resources that have been especially helpful in determining hierarchy of evidence; one by R. Brian Haynes called the
6S Hierarchy of Preapprasied Evidence and one by Bernadette Melnyk and Ellen Fineout-Overholt called
Hierarchy of Evidence for Interventional Studies.
Haynes 6S Model is based on a pyramid approach to evidence. At the base of the pyramid are original studies that are published in journals and at the peak of the pyramid are the computerized decison support systems that integrate evidence at point-of-care. In between these levels are synopses of studies and randomized controlled trials, meta-analyses, systematic reviews, and evidence-based clinical practice guidelines. The Hierarchy of Evidence for Interventional Studies by Melynk and Fineout-Overholt, lists the types of evidence in a table style and gives a description of each level of evidence. Being a visual learner, these formats brought clarity to where I was going in my literature search and helped me to determine which articles were of less importance.
The next time you do a search on a topic, I suggest you pull out these two models to use as a guide to determine the hierarchy of evidence you are reviewing.