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Estimation of Personalized Effects Associated With Causal Pathways
Proceedings of the 34th Conference on Uncertainty in Artificial Intelligence, PMLR R16:672-681, 2018.
Abstract
The goal of personalized decision making is to map a unit’s characteristics to an action tai- lored to maximize the expected outcome for that unit. Obtaining high-quality mappings of this type is the goal of the dynamic regime lit- erature. In healthcare settings, optimizing poli- cies with respect to a particular causal pathway may be of interest as well. For example, we may wish to maximize the chemical effect of a drug given data from an observational study where the chemical effect of the drug on the outcome is entangled with the indirect effect mediated by differential adherence. In such cases, we may wish to optimize the direct ef- fect of a drug, while keeping the indirect effect to that of some reference treatment. [15] shows how to combine mediation analysis and dy- namic treatment regime ideas to defines poli- cies associated with causal pathways and coun- terfactual responses to these policies. In this paper, we derive a variety of methods for learn- ing high quality policies of this type from data, in a causal model corresponding to a longitu- dinal setting of practical importance. We illus- trate our methods via a dataset of HIV patients undergoing therapy, gathered in the Nigerian PEPFAR program.