Harm-Threshold Utilitarianism: A Novel Ethical Framework for Organ Transplant Allocation

Organ allocation policies face a fundamental tension: maximizing total survival benefitversus protecting fairness for the sickest patients. Current systems, such as the Model forEnd-Stage Liver Disease (MELD), save many lives by prioritizing urgency, but they can reducelong-term survival gains. We introduce Harm-Threshold Utilitarianism (HTU), a frameworkthat seeks to maximize expected post-transplant benefit while enforcing guardrails for epis-temic confidence, catastrophic harm, and computational simplicity. Using retrospective U.S.liver transplant registry data, we simulated organ offers under HTU and MELD. HTU consis-tently selected candidates with greater predicted post-transplant survival, producing measurableimprovements in 5-year restricted mean survival time (≈ 0.25 years per transplant) withoutsystematically abandoning high-risk patients. Sensitivity analyses show that the harm thresholdgoverns the trade-off between efficiency and urgency, while the epistemic screen curbs over-reliance on uncertain model differences. By making these thresholds explicit, HTU transformsimplicit value judgments into transparent rules. The approach offers a principled path towardorgan allocation policies that are both ethically defensible and outcome-improving.