This is a general set of levels to aid in critically evaluating evidence. It was adapted from the model presented in the book, Evidence-Based Practice in Nursing and Healthcare: A Guide to Best Practice (Melnyk & Fineout-Overholt, 2019). Some specialties may have adopted a slightly different and/or smaller set of levels.
Evidence from a clinical practice guideline based on systematic reviews or meta-analyses of randomized controlled trials. Is this is not available, then evidence from a systematic review or meta-analysis of random controlled trials.
Evidence from randomized controlled studies with good design.
Evidence from controlled trials that have good design but are not randomized.
Evidence from case-control and cohort studies with good design.
Evidence from systematic reviews of qualitative and descriptive studies.
Evidence from qualitative and descriptive studies.
Evidence from the opinion of authorities and/or the reports of expert committees.
The pyramid below is a hierarchy of evidence for quantitative studies. It shows the hierarchy of studies by study design; starting with secondary and reappraised studies, then primary studies, and finally reports and opinions, which have no study design. This pyramid is a simplified, amalgamation of information presented in the book chapter “Evidence-based decision making” (Forest et al., 2019) and book Evidence-Based Practice in Nursing and Healthcare: A Guide to Best Practice (Melnyk & Fineout-Overholt, 2019).
Advocate Health - Midwest provides system-wide evidence based practice resources. The Nursing Hub* has an Evidence-Based Quality Improvement (EBQI) Evidence Table, within the Evidence-Based Practice (EBP) Resource. It also includes information on evidence type, and a literature synthesis table.
*The Nursing Hub requires access to the Advocate Health - Midwest SharePoint platform.
Forrest, J. L., Miller, S. A., Miller, G. W., Elangovan, S., & Newman, M. G. (2019). Evidence-based decision making. In M. G. Newman, H. H. Takei, P. R. Klokkevold, & F. A. Carranza (Eds.), Newman and Carranza's clinical periodontology (13th ed., pp. 1-9.e1). Elsevier.
