Optimal use of a ‘scarce resource’ – a revised UK Kidney Offering Scheme

At the Irish Nephrology Society Annual Meeting 2025, delegates heard from Prof Lorna Marson, Professor of Transplant Surgery and Consultant Surgeon at the Royal Infirmary of Edinburgh, who provided valuable insight into the development of a revised national kidney allocation policy in the UK. Prof Marson also serves as Non-Executive Director of NHS Blood and Transplant – the strategic health authority that oversees organ transplantation and blood transfusion in the UK – and was Deputy Chair of the Kidney Advisory Group that initiated a review of the 2006 Kidney Allocation Scheme in 2015.

Prof Marson began by emphasising the discrepancies between supply and demand of kidneys in the UK and Ireland – and the subsequent need for a national offering scheme. She said “we have to make the best use of this scarce resource”.

Attendees heard that the “overarching principle” of the 2006 scheme was to optimise the human leukocyte antigen (HLA) match, particularly for children, which was based on earlier evidence demonstrating a “significantly improved graft survival for those very well matched at HLA level”.

Prof Marson then described the formation of three working groups in 2015 to assess the need for amendments to the scheme, and to “really look at improving equity of access to kidney transplantation”. The working groups were responsible for reviewing the 2006 scheme; assessing the philosophy of kidney allocation; and looking at HLA. Prof Marson served as Chair of the group that reviewed the 2006 scheme.

“When we reviewed the 2006 scheme, we found a high number of declined offers. These offers were made for standard criteria donors after brain death, so one would anticipate that these are higher quality kidneys that most people would accept when offered for their patients,” Prof Marson said, adding that decline rates varied among centres. She also said that patients who had been waiting over seven years “were almost exclusively difficult to match”, adding that matchability scores (based on the recipient’s blood group, HLA type, and unacceptable antigens) – which had not yet been utilised in allocation – could have predicted who would have waited a long time.

“Reflecting on the review of the data from the 2006 scheme, we recommended removing absolute priority for full house match patients to offer more advantage for patients who are difficult to match. We recommended introducing the use of matchability scores to predict patients that will become long waiters and offer them a significant advantage before they have to wait the seven years…. We also believed we should be matching graft life expectancy with patient life expectancy. The philosophy of allocation group recommended again that highly sensitised patients should receive prioritisation, which aligned with our recommendations.”

Prof Marson admitted there had been “a lot of discussion” about the role of age during the review, with an eventual agreement that it should be “a continuous factor”, rather than serve as a mere cut-off at 18 years for paediatrics. She also told the conference that the waiting time start on the transplant list was agreed to be either at the point of activation on the list or the earliest start on dialysis. “This is still a point for debate,” she added, “because the patient should only be pre-emptively listed if it is believed they are within six months of needing dialysis, but this audience will know that is more an art than a science.”

The conference also heard that the HLA working group recommended “extending the repertoire for donor HLA typing”, improving the matching of various loci, and that difficult to match patients should be flagged to transplant units.

“As a transplant surgeon that receives calls in the middle of the night, it’s great if someone can tell me the person has a matchability score of 10, because that really changes my decision-making about whether to accept what I might consider a more marginal kidney given that the patient is unlikely to receive another offer.”

The conference also heard that the HLA group advocated no exclusion criteria for HLA antigen matches in difficult to match patients and that an array of other recommendations and objectives were achieved.

“We also unified donors after brain death and circulatory death so that all the deceased donor kidneys are allocated through this national scheme. We want to provide more quality matching between donor and recipient and tailor that HLA matching so that young patients who require well-matched kidneys are offered it and that elderly patients, who are perhaps less likely to require a subsequent transplant, might be offered a kidney more rapidly. We also want to avoid prolonged waiting times that are predictable.”

The conference also heard that donor and recipient risk indices were developed using adult donor and recipient data early during the review period to allow matching between high-quality donors and recipients and “to see if they could then inform our new offering scheme”.

Prof Marson said that statistical models related to five-year graft survival showed that low-risk donors have significantly improved graft survival at five years, and that high-quality recipients, such as younger and pre-emptive patients, also have a much-improved transplant survival at five years. She also explained that matching high-quality donors with high-quality recipients resulted in a higher kidney acceptance rate.

Prof Marson then described the introduction of the new, two-tiered kidney offering scheme in 2019, where tier A are prioritised by a matchability score of 10 and waiting time from dialysis, and tier B are “all other patients that are prioritised by a points score, which takes into account the donor-recipient indices match, waiting time, and those HLA match and age points combined”.

Concluding with a summary of findings from a 2023 review of the new scheme, Prof Marson said: “The aim was to try to improve equity of access to a national resource, to more effectively match the donor and recipient, and to avoid long waiting times that were predictable. We’ve been massively affected by the pandemic, but overall, we believe the scheme is meeting expectations. Highly sensitised patients are having improved access to transplant, we’re getting more equitable access to transplantation across different ethnic groups, and the donor-recipient matching is beginning to demonstrate a reduction in offer declines, particularly related to age.”