Open AccessEffect Decomposition in the Presence of an Exposure-Induced Mediator-Outcome Confounder
Author(s) -
Tyler J. VanderWeele,
Stijn Vansteelandt,
James M. Robins
Publication year - 2014
Publication title -
epidemiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.901
H-Index - 173
eISSN - 1531-5487
pISSN - 1044-3983
DOI - 10.1097/ede.0000000000000034
Subject(s) - confounding , mediation , causal inference , outcome (game theory) , mediator , indirect effect , weighting , inference , econometrics , medicine , psychology , computer science , mathematics , artificial intelligence , mathematical economics , political science , law , radiology
Methods from causal mediation analysis have generalized the traditional approach to direct and indirect effects in the epidemiologic and social science literature by allowing for interaction and nonlinearities. However, the methods from the causal inference literature have themselves been subject to a major limitation, in that the so-called natural direct and indirect effects that are used are not identified from data whenever there is a mediator-outcome confounder that is also affected by the exposure. In this article, we describe three alternative approaches to effect decomposition that give quantities that can be interpreted as direct and indirect effects and that can be identified from data even in the presence of an exposure-induced mediator-outcome confounder. We describe a simple weighting-based estimation method for each of these three approaches, illustrated with data from perinatal epidemiology. The methods described here can shed insight into pathways and questions of mediation even when an exposure-induced mediator-outcome confounder is present.