Developing a standardized, expert-validated taxonomy and evidence hierarchy for review typologies: A multi-methods...

Area of Science:

• Scientific methodology
• Evidence synthesis
• Research taxonomy

Background:

• Existing review typologies lack standardization, causing confusion in selection.
• Current evidence hierarchies often overlook the methodological nuances of reviews.
• A clear framework is needed to assess the rigor of different review types.

Purpose of the Study:

• To create an expert-validated taxonomy of review typologies.
• To establish an evidence hierarchy ranking reviews by methodological rigor and certainty.
• To standardize the selection and appraisal of scientific reviews.

Main Methods:

• Systematic literature review of 70 review typologies across six databases and grey literature.
• Three-round Delphi process with 67 international experts to refine typologies and achieve consensus (Kendall's W = 0.90).
• Appraisal using adapted GRADE and ROBIS tools, with a composite scoring algorithm to determine hierarchy placement.

Main Results:

• Identified 70 distinct review typologies, consolidated into 13 functionally distinct types.
• Developed a three-tier evidence hierarchy: Tier 1 (high-certainty: meta-analyses, overviews), Tier 2 (moderate-certainty: systematic, scoping, rapid, RE-AIM), Tier 3 (low-certainty: narrative, realist, integrative, mapping).
• Hierarchy reflects a gradient of methodological rigor, from exploratory to protocol-driven methods.

Conclusions:

• A validated three-tier taxonomy and hierarchy for review typologies are proposed.
• The framework enhances clarity, comparability, and transparency in evidence synthesis.
• Provides a practical foundation for selecting appropriate review methods, supporting evidence-based practice and policy.