Related Experiment Videos

Structured tools for assessing quality and risk of bias in Mendelian randomization studies: an updated systematic

Jinyue Yu1,2,3, Mengxuan Zou1, Francesca Spiga1

  • 1Population Health Sciences, Bristol Medical School, University of Bristol, Bristol, United Kingdom.

International Journal of Epidemiology
|April 18, 2026
PubMed
Abstract

Insights

The number of Mendelian randomization (MR) quality assessment tools has increased, but a lack of standardization hinders comparisons across studies. Developing standardized frameworks is crucial for improving MR research quality.

Area of Science:

  • Epidemiology
  • Genetic Epidemiology
  • Biostatistics

Background:

  • Mendelian randomization (MR) is increasingly used, necessitating robust quality and bias assessment tools.
  • A prior review identified 14 MR instruments up to July 2021.
  • Methodological advancements have continued since the last review.

Purpose of the Study:

  • To update a systematic review of MR quality and bias assessment tools.
  • To identify tools published between July 2021 and January 2025.

Main Methods:

  • An updated systematic review was conducted using the previous search strategy and eligibility criteria.
  • Two reviewers independently screened articles, extracted data, and mapped tool content to bias domains.

Main Results:

  • Fifteen additional articles were identified, totaling 29 MR tools.
  • Nineteen of these tools provide structured evaluations, with twelve being newly identified.
  • Newer tools cover broader domains beyond core assumptions, but significant variation in structure and scoring persists.
  • Gaps remain in assessing linkage disequilibrium, missing data, and dynastic effects.

Conclusions:

  • The increase in MR evaluation tools is noted, but standardization is lacking.
  • Lack of standardization impedes comparisons across systematic reviews.
  • Developing comprehensive, standardized evaluation frameworks is essential for enhancing MR research quality.
Keywords:
Mendelian randomizationevaluation toolsquality assessmentrisk of biassystematic review

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