Introduction:In 2015, three working groups were established to consider whether changes were required to the 2006 UK Kidney Allocation Scheme to reflect the increased use of donors after circulatory death (DCD) and generally older, more challenging donor kidneys. The three groups were tasked with reviewing the current scheme, looking at philosophy of allocation and looking at histocompatibility and immunogenetics, respectively. The working groups agreed that a new Kidney Offering Scheme should be introduced to better match patient and graft life expectancy, to give more priority to difficult to match patients and, where HLA matching is deemed appropriate, all loci should be considered (HLA- A, B, Cw, DR, DQ).
Material and Methods: In line with agreed objectives, a series of computer simulations were used to explore a number of different offering scheme algorithms. The simulations were developed using 4100 UK deceased kidney donors that resulted in a transplant, 2013-2016, 5300 patients listed in the UK for a kidney only transplant at 1 January 2012 and 8200 patients newly listed for a kidney only transplant, 2012-2016. Each simulation represented four years of constant activity. Simulation results of different possible schemes were compared according to characteristics of the simulated transplant and waiting list pools in order to find the best compromise between competing objectives. The simulations included use of donor and recipient risk indices developed with the working groups.
Results and Discussions:The proposed scheme allocates all deceased donor kidneys to patients in two tiers.  Tier A includes patients that are very difficult to match or have waited ≥7 years to transplant and are prioritised by waiting time. Tier B includes all other patients and they are prioritised by a points score reflecting recipient waiting time, recipient age x HLA match and donor-recipient risk index combinations. The proposed scheme will increase transplants for difficult to match and ethnic minority patients, to reduce the build-up of these patients on the current waiting list. The scheme will also match donor and recipients more effectively in terms of their risk indices in order to maximise utility from donated kidneys. A number of other advantages of the proposed scheme include improved equity of access across different patient groups.
Conclusions: A new Kidney Offering Scheme in the UK is being developed to reflect the changing donor pool and to address some of the inequities observed in the current scheme (introduced in 2006). The new scheme will allocate all kidneys from both DBD and DCD donors and will more effectively match graft life expectancy with patient life expectancy.