Levels of Evidence
In order for health professionals to practice evidence-based medicine and make evidence-informed decisions, they must first consider the quality of evidence at hand. In order to make this easier, a variety of research centers and national organizations around the world have created hierarchies of evidence. All of them advise the reader that these are likely (but not always) the best sources evidence.
Levels of Evidence Pyramid
- Image from Evidence-Based Medicine Resource Guide, Georgetown University
Levels of Evidence, Agency for Healthcare Research and Quality (US)
| Level of evidence | |
| Level I | Meta-analysis of multiple studies |
| Level II | Experimental studies |
| Level III | Well-designed, quasi-experimental studies |
| Level IV | Well-designed, non-experimental studies |
| Level V |
Case reports and clinical examples |
In Clair JS. A New Model of Tracheostomy Care: Closing the Research–Practice Gap. In: Henriksen K, Battles JB, Marks ES, et al., editors. Advances in Patient Safety: From Research to Implementation (Volume 3: Implementation Issues). Rockville (MD): Agency for Healthcare Research and Quality (US); 2005 Feb. Available from: https://www.ncbi.nlm.nih.gov/books/NBK20542/
Levels of Evidence, Center for Evidence-Based Medicine, University of Oxford
Levels of Evidence, Center for Evidence-Based Medicine, University of Oxford
