Results on Confounding and Misclassification for Gene-Gene and Gene-Environment Interactions

• Activity Number: 142
• Type: Invited
• Date/Time: Monday, August 1, 2011 : 10:30 AM to 12:20 PM
• Sponsor: ENAR
• Author(s): Tyler J. VanderWeele*+
• Companies: Harvard University
• Keywords: Causal inference ; Confounding ; Misclassification ; Gene-gene ; Gene-environment

Abstract

Studies of gene-gene and gene-environment interaction may be subject to confounding of either the genetic or environment factors; both factors may also be subject to misclassification. Bias formulas for sensitivity analysis for interaction under unmeasured confounding are given on both additive and multiplicative scales. Simplified formulas are provided in the case in which one of the two factors does not interact with the unmeasured confounder in its effects on the outcome. An interesting consequence of the results are that if the two exposures of interest are independent (e.g. gene-environment independence) then even under unmeasured confounding if the estimated interaction is non-zero then either there is a true interaction between the two factors or there is an interaction between one of the factors and the unmeasured confounder; an interaction must be present in either scenario. It is moreover shown that when one or both exposures are misclassified, a non-zero interaction for the misclassified exposures will imply non-zero interaction for the true exposures provided misclassification is independent and nondifferential and the sensitivity and specificity satisfy certain bounds.