Causal effect estimation from data simulating instrument correlations, instrument strength, and horizontal pleiotropy.

<p><b>(A)</b> Causal diagram for the simulation of two exposures <i>X</i><sub>1</sub> and <i>X</i><sub>2</sub> for an outcome <i>Y</i>, with two shared instruments <i>E</i><sub>1</sub> and <i>...

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Bibliographic Details
Main Author: Mariyam Khan (20161530) (author)
Other Authors: Adriaan-Alexander Ludl (9321107) (author), Sean Bankier (15152851) (author), Johan L. M. Björkegren (7759127) (author), Tom Michoel (29810) (author)
Published: 2024
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Summary:<p><b>(A)</b> Causal diagram for the simulation of two exposures <i>X</i><sub>1</sub> and <i>X</i><sub>2</sub> for an outcome <i>Y</i>, with two shared instruments <i>E</i><sub>1</sub> and <i>E</i><sub>2</sub> with pairwise covariance <i>α</i> and matrix of instrument effect sizes <i>A</i> = [<i>a</i><sub><i>ij</i></sub>]. <b>(B)</b> Difference () between estimated and true causal effect of <i>X</i><sub>1</sub> (true effect size <i>c</i> = 0.2) on <i>Y</i> across 1,000 independently simulated datasets for a range of sample sizes. <b>(C,D)</b> Distribution of the difference between estimated and true causal effects for <i>X</i><sub>1</sub> (left; true effect size <i>c</i> = 0.2) and <i>X</i><sub>2</sub> (right; true effect size <i>c</i> = 0.6) across 1,000 independently simulated datasets and a range of sample sizes comparing strong (0.1 − 0.3) vs weak (0.001 − 0.01) instruments. <b>(E)</b> False causal diagram used for inference where one causal exposure is missing. <b>(F-G)</b> Difference between estimated and true causal effect of <i>LPA</i> (left, true effect size <i>c</i><sub><i>LPA</i></sub> = −0.05) and <i>PLG</i> (right, true effect size <i>c</i><sub><i>PLG</i></sub> = −0.27) on <i>Y</i> across 1,000 independently simulated datasets with sample size 2000 across a range of effect sizes of the hidden gene <i>SLC22A3</i> mediating horizontal pleiotropic effects of the instruments on <i>Y</i>, showing both the estimates with the correct model (green) and the estimates with the hidden exposure model (orange). See <a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1011473#sec002" target="_blank">Methods</a> for simulation details.</p>