Instrumental variable analysis with a nonlinear exposure-outcome relationship.

ABSTRACT:

Background

Instrumental variable methods can estimate the causal effect of an exposure on an outcome using observational data. Many instrumental variable methods assume that the exposure-outcome relation is linear, but in practice this assumption is often in doubt, or perhaps the shape of the relation is a target for investigation. We investigate this issue in the context of Mendelian randomization, the use of genetic variants as instrumental variables.

Methods

Using simulations, we demonstrate the performance of a simple linear instrumental variable method when the true shape of the exposure-outcome relation is not linear. We also present a novel method for estimating the effect of the exposure on the outcome within strata of the exposure distribution. This enables the esti

SUBMITTER: Burgess S 

PROVIDER: S-EPMC4222800 | biostudies-literature | 2014 Nov

REPOSITORIES: biostudies-literature