Unintended Consequences of the New National Kidney Allocation Policy in the United States

Abstract

The new national Kidney Allocation System of the Organ Procurement and Transplantation Network (OPTN), effective as of December 4, 2014, was designed to improve the chances of transplanting the most highly sensitized patients on the waitlist, those with calculated panel reactive antibody values of 98%, 99% and 100%. Recently, it was suggested that these highly sensitized patients will experience inequitable access, given the reported high prevalence of antibodies to HLA‐DP, and the fact that only about 1/3 of deceased donors are typed for HLA‐DP antigens. Here we report that 320/2948 flow cytometric crossmatches performed for the Northwestern transplant program over the past 28 months were positive solely due to HLA‐DP donor‐specific antibodies (11%; 16.5% of patients with HLA antibodies—sensitized patients). We further show that 58/207 (12%) HLA‐DR serologically matched donor‐recipient pairs had a positive B cell flow crossmatch due to donor‐specific HLA class II antibodies, and 2/34 (6%) serologic zero‐HLA‐A‐B‐DR mismatch had a positive flow crossmatch due to HLA‐DSA. We therefore provide information regarding the necessity and importance of complete donor HLA typing including both chains of the HLA‐DP antigen (encoded by HLA‐DPA1 and HLA‐DPB1) at the time of organ offer.

Evolving Trends in Racial Disparities for Peri-Operative Outcomes with the New Kidney Allocation System (KAS) Implementation

“…These particular antibodies were found in 63% of highly sensitized wait list patients in a study done including 593 candidates with the aforementioned descriptors. It is difficult to know how the omission of this testing could lead to different post-operative outcomes, but important to acknowledge for future research [17–19].…”

Allocating Deceased Donor Kidneys to Candidates with High Panel–Reactive Antibodies

“…Because these candidates now receive regional and national priority for DD kidneys (13), more than one-half of the kidneys allocated to highly sensitized candidates are to candidates with HLA class 2 antibodies not accounted for in the OPTN's current data system. A recent study by Tambur et al (23) revealed that 320 of 2948 (11%) flow cytometric B cell crossmatches among waitlisted candidates and their prospective donors were positive solely because of HLA-DP donor specific antibodies. A positive crossmatch may halt the anticipated transplant and require a local backup substitute or returning the organ for reallocation.…”

Pediatric deceased donor kidney transplant outcomes under the Kidney Allocation System

“…Although early simulations suggested that pDDKT would remain unchanged after KAS implementation, changes in the allocation system can produce unintended consequences. 2,5 Early reports on the effect of KAS were encouraging, with studies showing an increase in transplant rates for highly sensitized patients and African American patients in the first year after KAS implementation, without a change in overall pDDKT rate. 6,7 Nevertheless, a longer-term study showed that children <6 years old were 21% less likely to undergo DDKT after KAS implementation.…”