Glossary Term
Levels Of Evidence
Levels of evidence provide a framework to describe the strength of results obtained from clinical trials or research studies. The Brookbush Institute, as described by Shekelle et al., identifies five levels of evidence: IA (evidence from meta-analysis of randomized controlled trials), IB (evidence from at least one randomized controlled trial), IIA (evidence from at least one controlled study without randomization), IIB (evidence from at least one other type of quasi-experimental study), and III (evidence from non-experimental descriptive studies). However, levels of evidence should not supersede the evaluation of an experienced professional and should be viewed as guidelines. Synonyms for levels of evidence include strength of evidence, quality of evidence, and hierarchy of evidence.
Levels of Evidence: Relative to evidence-based practice, levels of evidence are an attempt to describe the strength of the results measured in a clinical trial or research study. Note: levels of evidence do not supersede the critical evaluation of research, and should be viewed as guidelines - a meta-analysis may be poorly constructed (Level IA), and a comparative study (Level III) may employ new technologies and a strong methodology. The Levels of Evidence used by the Brookbush Institute, as described by Shekelle et al.(1):
- IA - Evidence from meta-analysis of randomized controlled trials
- IB - Evidence from at least one randomized controlled trial
- IIA - Evidence from at least one controlled study without randomization
- IIB - Evidence from at least one other type of quasi-experimental study
- III - Evidence from non-experimental descriptive studies, such as comparative studies, correlation studies, and case-control studies
- IV - Evidence from expert committee reports or opinions or clinical experience of respected authorities, or both
- Shekelle, P. G., Woolf, S. H., Eccles, M., & Grimshaw, J. (1999). Developing clinical guidelines. Western Journal of Medicine, 170(6), 348.
Comments
Synonyms
- Strength of evidence
- Quality of evidence
- Hierarchy of evidence