Geographic disparities in liver supply/demand ratio within fixed‐distance and fixed‐population circles

Recent OPTN proposals to address geographic disparity in liver allocation have involved circular boundaries: the policy selected 12/17 allocated to 150‐mile circles in addition to DSA s/regions, and the policy selected 12/18 allocated to 150‐mile circles eliminating DSA /region boundaries. However, methods to reduce geographic disparity remain controversial, within the OPTN and the transplant community. To inform ongoing discussions, we studied center‐level supply/demand ratios using SRTR data (07/2013‐06/2017) for 27 334 transplanted deceased donor livers and 44 652 incident waitlist candidates. Supply was the number of donors from an allocation unit ( DSA or circle), allocated proportionally (by waitlist size) to the centers drawing on these donors. We measured geographic disparity as variance in log‐transformed supply/demand ratio, comparing allocation based on DSA s, fixed‐distance circles (150‐ or 400‐mile radius), and fixed‐population (12‐ or 50‐million) circles. The recently proposed 150‐mile radius circles (variance = 0.11, P  = .9) or 12‐million‐population circles (variance = 0.08, P  = .1) did not reduce the geographic disparity compared to DSA ‐based allocation (variance = 0.11). However, geographic disparity decreased substantially to 0.02 in both larger fixed‐distance (400‐mile, P  < .001) and larger fixed‐population (50‐million, P  < .001) circles ( P  = .9 comparing fixed distance and fixed population). For allocation circles to reduce geographic disparities, they must be larger than a 150‐mile radius; additionally, fixed‐population circles are not superior to fixed‐distance circles.