Impact of the new kidney allocation system A2/A2B → B policy on access to transplantation among minority candidates

Abstract

Blood group B candidates, many of whom represent ethnic minorities, have historically had diminished access to deceased donor kidney transplantation (DDKT). The new national kidney allocation system (KAS) preferentially allocates blood group A2/A2B deceased donor kidneys to B recipients to address this ethnic and blood group disparity. No study has yet examined the impact of KAS on A2 incompatible (A2i) DDKT for blood group B recipients overall or among minorities. A case-control study of adult blood group B DDKT recipients from 2013 to 2017 was performed, as reported to the Scientific Registry of Transplant Recipients. Cases were defined as recipients of A2/A2B kidneys, whereas controls were all remaining recipients of non-A2/A2B kidneys. A2i DDKT trends were compared from the pre-KAS (1/1/2013-12/3/2014) to the post-KAS period (12/4/2014-2/28/2017) using multivariable logistic regression. Post-KAS, there was a 4.9-fold increase in the likelihood of A2i DDKT, compared to the pre-KAS period (odds ratio [OR] 4.92, 95% confidence interval [CI] 3.67-6.60). However, compared to whites, there was no difference in the likelihood of A2i DDKT among minorities post-KAS. Although KAS resulted in increasing A2/A2B→B DDKT, the likelihood of A2i DDKT among minorities, relative to whites, was not improved. Further discussion regarding A2/A2B→B policy revisions aiming to improve DDKT access for minorities is warranted.

For the many: permitting deceased donor kidney transplantation across low‐titre blood group antibodies can reduce wait times for blood group B recipients, and improve the overall number of 000MMtransplants ‐ a multicentre observational cohort study

“…The use of A2 to O or B recipients has been permissible and recommended for some time, resulting in a reduction in waiting times and comparable graft outcomes to conventional compatible transplantation . Initially, the number of participating centres participating was low , however, the new Kidney Allocation Scheme in the USA has led to a significant increase in A2 donors being used for ABO‐incompatible transplants . Additionally, there is mounting evidence that for patients with low‐titres of anti‐A or anti‐B antibody (<1:16), there is no requirement for any augmentation to conventional immunosuppression, or need for desensitization therapy with plasmapheresis .…”

“…However, clinical exploitation of this phenomenon has been limited ‐ in a retrospective analysis of A2 kidney use in the USA, it was found that only 15% of the possible A2 allografts had been allocated to O or B recipients . Nonetheless, the recent changes in the US Kidney Allocation Scheme (KAS) allow A2 to B or O allocation and demonstrate improved rates of transplantation for Blood Group B recipients, albeit with little of the predicted effect on rates of transplantation for ethnic minorities . Centres for liver and infant heart transplantation, by necessity because of organ shortage, have developed a practice of ddABOi transplantation .…”

Allocation of deceased donor kidneys: A review of international practices

“…While the transplant rate for younger recipients increased, it fell modestly for those aged ≥65 years (who would benefit most from early transplantation). No increase in transplant rates for blood group B recipients was observed due to the low uptake of A 2 and A 2 B kidneys, especially in ethnic minorities for which this initiative was targeted . There was also a marginal increase in the non‐utilization rate.…”

KAS Turns Four: The State of Deceased Donor Kidney Allocation in the U.S.

“…Though subtype-compatible transplants have increased sharply with KAS ( Figure 5), the provision for transplanting A 2 or A 2 B kidneys into compatible blood type B candidates, who are still biologically disadvantaged due to relatively few donors having blood type B [3,40], remains underutilized [42,43]. Though an OPTN study found blood type to be the candidate characteristic third-most associated with disparities in transplant access, the factor most associated with disparities is geography, most notably the DSA of a candidate's transplant program [40,44].…”