UC Library Guides: Evidence-Based Practice in Health: Hierarchy of Evidence (2024)

FAQs

What is the hierarchy of evidence in evidence-based practice? ›

The hierarchy of evidence is a core principal of EBM. EBM hierarchies rank study types based on the strength and precision of their research methods. Different hierarchies exist for different question types, and even experts may disagree on the exact rank of information in the evidence hierarchies.

Because a prognosis question does not involve comparing treatments, the highest evidence would come from a cohort study or a systematic review of cohort studies.

Systematic Reviews and Meta Analyses

Well done systematic reviews, with or without an included meta-analysis, are generally considered to provide the best evidence for all question types as they are based on the findings of multiple studies that were identified in comprehensive, systematic literature searches.

Evidence hierarchies rank different research or evaluation study designs based on the rigour of their research methods. Evidence hierarchies vary, with different organisations using different criteria to group study designs.

For example, systematic reviews are at the top of the pyramid, meaning they are both the highest level of evidence and the least common. As you go down the pyramid, the amount of evidence will increase as the quality of the evidence decreases.

These shortcomings include the failure to define key terms, provide a comprehensive list of design flaws, demonstrate the reliability of such grading systems, properly value non-randomized controlled trials, and develop theoretically-derived systems for penalizing and promoting the evidence generated by a study.

There is the potential for the introduction of bias especially if there is incomplete data collection or follow-up which may happen with retrospective study designs. Also, these studies are usually based on a single surgeon's or center's experience which may raise doubts as to the generalizability of the results.

Copies of sales invoices represent internally generated evidence, which is considered least reliable. Confirmations mailed by outsiders and correspondence between the auditor and suppliers represent more reliable externally generated evidence.

What is the most credible evidence? ›

Primary sources are often considered the most credible in terms of providing evidence for your argument, as they give you direct evidence of what you are researching. However, it's up to you to ensure the information they provide is reliable and accurate.

The most powerful type of evidence, direct evidence, needs no inference. The evidence itself is the proof. This includes the testimony of a witness who saw an incident or the confession of the perpetrator. Written forms of proof, such as letters or wills, are considered documentary evidence.

Best evidence includes empirical evidence from randomized controlled trials; evidence from other scientific methods such as descriptive and qualitative research; as well as use of information from case reports, scientific principles, and expert opinion.

In the GRADE approach to quality of evidence, randomised trials without important limitations constitute high quality evidence. Observational studies without special strengths or important limitations constitute low quality evidence. Limitations or special strengths can, however, modify the quality of the evidence.

Evidence is ranked on a hierarchy according to the strength of the results of the clinical trial or research study. The strength of results can be impacted by a variety of factors such as the study design, outcomes, and bias, as well as the results themselves.

The hierarchy of evidence (also known as the evidence-based pyramid) is depicted as a triangular representation of the levels of evidence with the strongest evidence at the top which progresses down through evidence with decreasing strength.

On the lowest level, the hierarchy of study designs begins with animal and translational studies and expert opinion, and then ascends to descriptive case reports or case series, followed by analytic observational designs such as cohort studies, then randomized controlled trials, and finally systematic reviews and meta- ...

A hierarchy of evidence, comprising levels of evidence (LOEs), that is, evidence levels (ELs), is a heuristic used to rank the relative strength of results obtained from experimental research, especially medical research. There is broad agreement on the relative strength of large-scale, epidemiological studies.

The Hierarchy of Evidence is a way to rank information in order to find the best evidence available. This is a part of Evidence-Based Practice (EBP); the search for strong evidence. Information near the top has undergone a thorough review process while those near the bottom have not and may be weak sources.