Variation amongst hierarchies of evidence

Area of Science:

• Medical research methodology
• Evidence-based practice

Background:

• Evidence-based standards are crucial for modern medicine's practice, funding, and governance.
• These standards rely on hierarchies of evidence for their development.
• Existing hierarchies of evidence can vary, potentially leading to inconsistent standards.

Purpose of the Study:

• To highlight the existence of different evidence hierarchies.
• To identify factors that cause variations among these hierarchies, independent of study design.
• To encourage critical assessment of the processes used in developing evidence-based standards.

Main Methods:

• Analysis of factors influencing the development of evidence hierarchies.
• Identification of four key factors: professional jurisdiction, practical concerns, methodological quality, and question importance.
• Examination of how these factors affect the ranking of evidence types, such as expert opinion and randomized controlled trials.

Main Results:

• Four factors independently influence the structure of evidence hierarchies.
• These factors can lead to the elevation of expert opinion or the devaluing of randomized controlled trials and meta-analyses.
• Variations in hierarchies can result in different evidence-based standards being applied.

Conclusions:

• Awareness of factors influencing evidence hierarchy development is essential.
• Critical evaluation of hierarchy development processes can improve the consistency and reliability of evidence-based standards.
• Understanding these influences promotes a more discerning approach to medical evidence appraisal.