Skip to main content

19.05.2017 | METHODS | Ausgabe 5/2017 Open Access

European Journal of Epidemiology 5/2017

Interpreting findings from Mendelian randomization using the MR-Egger method

European Journal of Epidemiology > Ausgabe 5/2017
Stephen Burgess, Simon G. Thompson
Wichtige Hinweise

Electronic supplementary material

The online version of this article (doi:10.​1007/​s10654-017-0255-x) contains supplementary material, which is available to authorized users.
An erratum to this article is available at http://​dx.​doi.​org/​10.​1007/​s10654-017-0276-5.


Mendelian randomization-Egger (MR-Egger) is an analysis method for Mendelian randomization using summarized genetic data. MR-Egger consists of three parts: (1) a test for directional pleiotropy, (2) a test for a causal effect, and (3) an estimate of the causal effect. While conventional analysis methods for Mendelian randomization assume that all genetic variants satisfy the instrumental variable assumptions, the MR-Egger method is able to assess whether genetic variants have pleiotropic effects on the outcome that differ on average from zero (directional pleiotropy), as well as to provide a consistent estimate of the causal effect, under a weaker assumption—the InSIDE (INstrument Strength Independent of Direct Effect) assumption. In this paper, we provide a critical assessment of the MR-Egger method with regard to its implementation and interpretation. While the MR-Egger method is a worthwhile sensitivity analysis for detecting violations of the instrumental variable assumptions, there are several reasons why causal estimates from the MR-Egger method may be biased and have inflated Type 1 error rates in practice, including violations of the InSIDE assumption and the influence of outlying variants. The issues raised in this paper have potentially serious consequences for causal inferences from the MR-Egger approach. We give examples of scenarios in which the estimates from conventional Mendelian randomization methods and MR-Egger differ, and discuss how to interpret findings in such cases.

Unsere Produktempfehlungen

e.Med Interdisziplinär


Mit e.Med Interdisziplinär erhalten Sie Zugang zu allen CME-Fortbildungen und Premium-Inhalten der Fachzeitschriften, inklusive eines Print-Abos.

e.Dent - Das Online-Abo für Zahnärzte


Mit e.Dent erhalten Sie Zugang zu allen zahnmedizinischen Fortbildungen und unseren zahnmedizinischen und ausgesuchten medizinischen Zeitschriften.

Supplementary material 1 (pdf 114 KB)
Über diesen Artikel

Weitere Artikel der Ausgabe 5/2017

European Journal of Epidemiology 5/2017Zur Ausgabe