*Purpose: The continuous distribution framework is required for all future organ allocation policies. Continuous distribution changes the allocation paradigm, prioritizing candidates according to a composite allocation score(CAS), a weighted sum of medical priority, candidate biology, patient access, and placement efficiency. This change in the policy requires designing weights for each attribute of the CAS, replacing priorities encoded in geographical boundaries of former allocation policies.

*Methods: We used simulation with optimization to find the weights of our CAS (Figure-1) with an objective to reduce overall death and not exceed the current travel burden, while maintaining the Acuity Circles special prioritization of status 1, pediatric, and ABO candidates. Outcomes using our CAS were compared to those using Acuity Circles over a three-year simulation using LSAM SRTR 07/01/2013 to 06/30/2016 data.

*Results: Compared to Acuity Circles, our CAS (Figure-1) decreased the number of deaths from 7771 to 7679, average travel distance (273NM vs 264NM), and median travel distance (201NM vs 186NM). Our CAS increased the graft travel distance only for high MELD and status 1 candidates while reducing travel distance for other candidates (Table-2.) The special prioritization of pediatric, status 1, and ABO O&B candidates remained in CAS, reducing deaths among these groups (Table-1).

*Conclusions: Our CAS reduced overall deaths and decreased travel burden while maintaining other transplant metrics at near-current values. Advanced computational tools, like simulation optimization algorithms, will be invaluable in creating policies for continuous distribution to achieve desired policy outcomes.

Figure 1. Composite allocation score (CAS)

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