STROBE-MR: Reporting guidelines for Mendelian randomization studies


27.10.2021 – An international team of researchers and experts, including Veronika Whitesell Skrivankova and Matthias Egger from ISPM, developed new reporting guidelines for observational studies using Mendelian randomization. The STROBE-MR guidelines were published in both JAMA and BMJ today.

Mendelian randomization (MR) is a statistical method that uses measured variation in genes to test for or estimate the causal effect of exposure on a health outcome. Over the past decade, advances in genetic technologies have enabled the identification of thousands of reproducible associations between genetic variation and relevant exposures, traits, and health outcomes. These genetic variations can be used as instrumental variables to analyse the effect of modifiable exposures on diseases. With such approach, MR aims to reduce bias from confounding (that is, by another factor that affects both the outcome and exposure) and from reverse causation, where the cause is said to be the effect (and vice versa).

Mendelian randomization has gained popularity as a method for establishing or estimating causality without having to conduct a traditional randomized controlled trial – the gold standard in epidemiology. Despite the growth in MR applications and methods and the increasing relevance of MR findings, the reporting quality of MR studies has been inconsistent. Incomplete and inadequate reporting of research hampers the assessment of the strengths and weaknesses of the reported studies. The STROBE-MR guidelines are intended to guide authors in reporting on Mendelian randomization studies clearly and transparently, to support editors and reviewers considering such studies for publication, and to help readers decide whether the results are valid and useful.

The development of the STROBE-MR guidelines followed the Enhancing the Quality and Transparency of Health Research (EQUATOR) methodological framework for guideline development and used the STROBE (Strengthening the Reporting of Observational Studies in Epidemiology) Statement as a starting point to develop a checklist tailored to Mendelian randomization studies. The checklist comprises 20 items and 30 sub-items that should be addressed when reporting a Mendelian randomization study, to ensure clarity and comprehensiveness.

The STROBE-MR Statement, which describes the process of development of the guidelines is being published alongside an Explanation and Elaboration document that explains the items of the STROBE-MR checklist and provides examples of transparent reporting. «We hope the final guidelines will serve the entire community and contribute to improving the reporting of MR studies in the future,» says Professor Matthias Egger. «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.»