Broadened Allocation of Pancreas Transplants Across Compatible ABO Blood Types

Current Organ Procurement and Transplantation Network (OPTN) policy restricts certain blood type-compatible simultaneous pancreas and kidney (SPK) transplants. Using the Kidney Pancreas Simulated Allocation Model, we examined the effects of 5 alternative allocation sequences that allowed all clinically compatible ABO transplants.

The study cohort included kidney (KI), SPK, and pancreas alone (PA) candidates waiting for transplant for at least 1 day between January 1, 2010, and December 31, 2010 (full cohort), and kidneys and pancreata recovered for transplant during the same period. Additionally, because the waiting list has shrunk since 2010, the study population was reduced by random sampling to match the volume of the 2015 waiting list (reduced cohort).

Compared with the current allocation sequence, R4 and R5 both showed an increase in SPK transplants, a nearly corresponding decrease in KI transplants, and virtually no change in PA transplants. Life-years from transplant and median years of benefit also increased. The distribution of transplants by blood type changed, with more ABO:A, B, and AB transplants performed, and fewer ABO:O across all transplant types (KI, SPK, PA), with the relative percent changes largest for SPK.

Broadened ABO compatibility allowances primarily benefitted SPK ABO:A and AB candidates. ABO:O candidates saw potentially reduced access to transplant. The simulation results suggest that modifying the current allocation sequence to incorporate broadened ABO compatibility can result in an increase in annual SPK transplants.