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New set of rules on reporting epidemiology studies that use Mendelian randomization will help readers evaluate and interpret the study results

27 October 2021

A team of international researchers and experts have produced a set of guidelines to assist researchers in reporting their Mendelian randomization studies clearly and transparently. The STROBE-MR guidelines will assist readers of such studies to decide whether the results are valid and useful.

Mendelian randomization (MR) is a statistical method that uses measured variation in genes to test for or estimate the causal effect of exposure to an agent or risk factor on a health outcome. It aims to reduce bias from reverse causation, where the cause is said to be the effect (and vice versa), and from confounding, where a third variable or factor influences both the independent and dependent variables, causing to wrongly estimate the relationship between these variables. These concepts are explained more fully in the Mendelian randomisation primer.

Mendelian randomization has gained traction as a method for establishing or estimating causality without having to conduct a traditional randomized controlled trial – the gold standard in epidemiology.

Yet, despite the increasing relevance and popularity of Mendelian randomization studies, empirical evidence indicates that their reporting is often incomplete or of inadequate quality, which may limit their credibility,” says Dr. Brent Richards, senior investigator at the Lady Davis Institute’s Centre for Clinical Epidemiology at the Jewish General Hospital, who led the papers.

The STROBE-MR Statement, which is published in a special communication in both JAMA and BMJ, will support journal editors and reviewers in considering MR studies for publication and will help readers decide whether the results are valid and useful. The statement is not an instrument to evaluate the quality of the Mendelian randomization research and should not be used as such, emphasizes Dr Richards.

The STROBE-MR Statement is intended to guide authors when reporting a Mendelian randomization study and comprises a checklist of 20 items and 30 sub-items.

The publication of the STROBE-MR Statement, together with a comprehensive Explanation and Elaboration document, is a first step toward implementing these reporting guidelines,” says Dr. Richards. “We hope the final guidelines will serve the entire community and contribute to improving the reporting of MR studies in the future. Next steps include encouraging journals to endorse and support adherence to these guidelines, translating the guidelines into various languages and keeping them updated to address new and existing challenges.”


'Strengthening the reporting of observational studies in epidemiology using Mendelian randomization: The STROBE-MR statement', JAMA. 2021;326(16):1614-1621. doi:10.1001/jama.2021.18236 and BMJ 2021;375:n2233. doi: 


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