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Reporting methodological issues of the mendelian randomization studies in health and medical research: a systematic

Shabab Noor Islam1, Tanvir Ahammed1, Aniqua Anjum1

  • 1Department of Statistics, Shahjalal University of Science and Technology, 3114, Sylhet, Bangladesh.

BMC Medical Research Methodology
|January 17, 2022
PubMed
Abstract

Insights

Mendelian randomization (MR) studies often lack proper reporting of instrumental variable (IV) assumptions. This review highlights common issues in genetic risk score (GRS) based MR studies, potentially misdirecting findings.

Area of Science:

  • Epidemiology
  • Genetics
  • Biostatistics

Background:

  • Mendelian randomization (MR) studies utilize genetic risk scores (GRS) as instrumental variables (IV) to address unmeasured confounding in observational research.
  • Despite the increasing use of MR, there is a notable scarcity in the reporting of methodological details and potential issues.
  • This systematic review addresses the need for improved transparency in MR study reporting.

Purpose of the Study:

  • To systematically review published Mendelian randomization (MR) studies.
  • To identify and categorize common reporting problems related to the assumptions of instrumental variables (IV).
  • To assess the methodological rigor in the application of GRS in MR analyses.

Main Methods:

  • A systematic review of clinical articles published between 2009 and 2019 was conducted.
  • Searches were performed across PubMed, Scopus, and Embase databases.
  • Ninety-seven MR studies were included, adhering to PRISMA guidelines, with data extraction on assumption verification, statistical methods, and sensitivity analyses.

Main Results:

  • Only 68% of studies empirically verified the relevance assumption, with 41.2% reporting appropriate statistical tests (R2, F-test).
  • Theoretical justifications for the second and third IV assumptions were clearly stated and discussed in only 35.1% of studies.
  • Reporting varied for estimation methods (two-stage least square: 30.9%, Wald estimator: 11.3%) and sensitivity analyses (44.3%).

Conclusions:

  • Incompleteness in justifying instrumental variable assumptions is a prevalent issue in MR studies.
  • This lack of rigorous reporting may lead to misinterpretation and misdirection of research findings.
  • Enhanced transparency and adherence to reporting guidelines are crucial for the validity of MR research.
Keywords:
Genetic risk scoresInstrumental variable analysis (IV)Mendelian randomizationSystematic review

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