Temporal Causal Mediation through a Point Process: Direct and Indirect Effects of Healthcare Interventions
This addresses the need for dynamic causal mediation analysis in healthcare, where existing methods are limited to regular intervals and simple models, though it is incremental in extending mediation analysis to temporal settings.
The paper tackled the problem of estimating direct and indirect effects of healthcare interventions from irregular time-series data by proposing a non-parametric mediator-outcome model with a temporal point process, demonstrating accurate estimation on semi-synthetic data and clinically meaningful trajectories on real-world blood glucose data after surgery.
Deciding on an appropriate intervention requires a causal model of a treatment, the outcome, and potential mediators. Causal mediation analysis lets us distinguish between direct and indirect effects of the intervention, but has mostly been studied in a static setting. In healthcare, data come in the form of complex, irregularly sampled time-series, with dynamic interdependencies between a treatment, outcomes, and mediators across time. Existing approaches to dynamic causal mediation analysis are limited to regular measurement intervals, simple parametric models, and disregard long-range mediator--outcome interactions. To address these limitations, we propose a non-parametric mediator--outcome model where the mediator is assumed to be a temporal point process that interacts with the outcome process. With this model, we estimate the direct and indirect effects of an external intervention on the outcome, showing how each of these affects the whole future trajectory. We demonstrate on semi-synthetic data that our method can accurately estimate direct and indirect effects. On real-world healthcare data, our model infers clinically meaningful direct and indirect effect trajectories for blood glucose after a surgery.