Causal Explanation-Guided Learning for Organ Allocation
Alessandro Marchese, Jeroen Berrevoets, Sam Verboven
A central challenge in organ transplantation is the extremely low acceptance rate of donor organ offers—typically in the single digits—leading to high discard rates and suboptimal use of available grafts. Current acceptance models embedded in allocation systems are non-causal, trained on observational data, and fail to generalize to policy-relevant counterfactuals. This limits their reliability for both policy evaluation and simulator-based optimization. In this work, we reframe organ-offer acceptance as a counterfactual prediction problem and propose a method to learn from routinely recorded—but often overlooked—refusal reasons. These refusal codes act as direction-only counterfactual signals: for example, a rejection reason such as “donor too old” implies acceptance might have occurred had the donor been younger. We formalize this setting and introduce ClexNet, a novel causal model that learns policy-invariant representations via balanced training and an explanation-guided augmentation loss. On synthetic data, ClexNet outperforms existing acceptance models in predictive performance, generalization, and calibration, offering a robust drop-in improvement for simulators and allocation policy evaluation. Beyond transplantation, our approach offers a general method for incorporating domain-expert feedback as directional supervision, improving performance in settings where only observational data is available.