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Evidence-Based Practice: Evidence, Study Designs, and Clinical Tools

Haynes Pyramid of the Hierarchy of Evidence

 

Haynes Pyramid describing the levels of evidence

Townsend W; Donovan K; Ginier E; MacEachern M; Mani N. "Integrated "5S" Levels of Organization of Evidence Pyramid". September 2015. (http://hdl.handle.net/2027.42/138965). CC BY 4.0 https://creativecommons.org/licenses/by/4.0/.  Adapted from: Haynes RB. Of studies, syntheses, synopses, summaries and systems: the “5S" evolution of services for evidence-based health care decisions. ACP J Club. 2006 Nov-Dec;145(3):A8-9.


In order to make an evidence-based decision in the clinical setting, an awareness of the levels of evidence is essential. Here you'll find the Haynes pyramid which guides you through the reliability of evidence found in the medical literature.

Definitions of Study Types

Meta-analysis: A systematic review that uses quantitative methods to synthesize and summarize the results.

Systematic Review: The application of strategies that limit bias in the assembly, critical appraisal, and synthesis of all relevant studies on a specific topic. SRs focus on peer-reviewed publications about a specific health problem and use rigorous, standardized methods for selecting and assessing articles.

Randomized Controlled Trial (RCT): An experiment in which subjects in a population are randomly sorted into two or more groups to receive or not receive an experimental preventative or therapeutic procedure or treatment. The two groups' results are then assessed to determine the effectiveness of the treatment.

Controlled Clinical Trial: These experiments are similar to RCTs except that the methods of selecting the groups are non-randomized. These types of studies are more likely to suffer from bias than RCTs.

Observational Study: A type of study in which the researchers compare people who receive an intervention to those who do not. The researchers are not involved in the selection of the population nor the original intervention, but instead compare the records of the patients who had been treated with the intervention to those who had not been treated. Examples of observational studies are cohort and case-control studies.

Case Series: A group or series of case reports involving patients who were given similar treatment. There is no comparison group for case series studies.

(Adapted from CEBM and Dahlgren Memorial Library)

Best Study Designs by Type of Clinical Question

Type of Question Most Appropriate Study Design
Diagnosis

Independent, blind comparison to a gold standard

Therapy

1. RCT

2. Cohort Studies

3. Case Control 

4. Case Series

Prognosis

1. Cohort Studies

2. Case Control

3. Case Series

Harm

1. Cohort Studies

2. Case Control

3. Case Series

Prevention

1. RCT

2. Cohort Studies

3. Case Control

4. Case Series

Swanberg SM, Mi M, Engwall K. An integrated, case-based approach to teaching medical students how to locate the best available evidence for
clinical care. MedEdPORTAL. 2017;13:10531. https://doi.org/10.15766/mep_2374-8265.10531

Summaries

Synopses

Syntheses

Studies

Background Resources

Integrated Clinical Tools

CONTACT

Email Butler University Libraries
Irwin Library: 317-940-9227
Science Library: 317-940-9937
CAT: 317-940-8575

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