First Report on the OPTN National Variance: Allocation of A2/A2B Deceased Donor Kidneys to Blood Group B Increases Minority Transplantation

Abstract

In 2002, the Organ Procurement and Transplantation Network (OPTN) Minority Affairs Committee (MAC) implemented a national, prospective, ''variance of practice'' to allow deceased donor, ABO blood group incompatible, A2 antigen, kidney transplantation into blood group B recipients; outcomes of this cohort were compared to ABO compatible recipients. The goal of the variance was to increase the number of transplants to B candidates without negatively impacting survival or compromising system equity. Only B recipients with low anti-A IgG titers (<1:8) were eligible to receive these kidneys. Across eight participating Donation Service Areas (DSA), there were 101 A 2 /A 2 B to B transplants through 12/31/11, of which the majority of the recipients (61%) were ethnic minorities. At 12, 24, and 36 months, Kaplan-Meier graft survival rates for the B recipients of A 2 /A 2 B kidneys were 95.0%, 90.6%, and 85.4%, respectively, comparable to outcomes for B recipients of B kidneys, 92.6%, 87.9%, and 82.5%, respectively (p-value ¼ 0.48). Five DSAs increased the proportion of B transplants during 41 months postvariance, with a lesser proportional decrease in blood group A transplants. The data support the proposition that this allocation algorithm may provide a robust mechanism to increase access of blood group B minority candidates to kidney transplantation.

Changes in Deceased Donor Kidney Transplantation One Year After KAS Implementation

“…An estimated 80% of blood type B candidates have low anti-A titers (27), yet only 3% have been reported as medically eligible (28) and less than one fifth of centers are participating, suggesting substantial room for growth in this area (29). However, the implementation of a protocol to perform these transplants is logistically challenging for transplant centers, and the increased resources required and risk incurred may be barriers to this element of KAS reaching its full potential.…”

The End of Racial Disparities in Kidney Transplantation? Not So Fast!

“…Furthermore, there was an estimated 10% overall increase in the rate of minority transplantation if this system were to be fully adopted. 11 As noted in the report, by April of 2015, only 3.6% of active B candidates in the United States had been registered to accept potential A 2 /A 2 B offers. Clearly, many more B candidates could be listed for the A 2 /A 2 B option than currently are taking advantage of it, potentially resulting in a substantial increase in minority transplant opportunities.…”

“…Clearly, many more B candidates could be listed for the A 2 /A 2 B option than currently are taking advantage of it, potentially resulting in a substantial increase in minority transplant opportunities. 11 The issue of biologic differences between populations affecting disparities in KT is not new. As noted by Purnell et al, 3 the OPTN/UNOS policy decision to eliminate priority allocation points by HLA-B antigen status (2003) has led to a roughly 20% reduction in disparity in the rates of DD KT between minority and white recipients and reduction in waiting time for minorities as well as improved KT outcomes for these patients.…”

A2/A2B to B Renal Transplantation: Past, Present, and Future Directions

“…Finally, biopsy data evaluating the histology of A 2 /A 2 B kidneys in blood group B candidates have not been reported. (17). Thus, the national blood group B transplantation rate may improve from 9% (17) to 34% (14).…”

“…B allocation system increases access of B candidates to deceased donor renal transplantation by diverting a portion of the A and AB kidneys from the A and AB candidate pool, it is crucial to know how much of an effect that diversion had on the transplantation rate of either A or AB candidates (15,17). We evaluated the speculative impact of this allocation algorithm on A and AB transplants by using 2013 OPTN data along with the actual transplant rate data generated by the OPTN/UNOS A 2 /A 2 B !…”