Increased Access to Transplantation for Blood Group B Cadaveric Waiting List Candidates by Using A2 Kidneys: Time for a New National System?

Abstract

Since blood group B end-stage renal disease (ESRD) patients have less access to donor kidneys and a higher minority composition than any other blood group, the United Network for Organ Sharing (UNOS) approved a voluntary national kidney allocation variance to allow organ procurement organizations (OPOs) to preferentially allocate A2 and A2B kidneys to B candidates. The Midwest Transplant Network OPO has preferentially allocated and transplanted kidneys from blood group A2 and A2B donors to our blood group B waiting list candidates for more than 7 years to increase access to kidneys for the B candidates on our OPO-wide waiting list. Between 1994 and 2000, a total of 121 blood group B ESRD patients from our OPO-wide cadaveric kidney waiting list were transplanted. Thirty-four per cent (41/121) of those B candidates received either an A2 or an A2B kidney. One- and 5-year graft survival rates for the group of B recipients of A2 or A2B kidneys were 91 and 85% (died with functioning graft [DWFG] censored), respectively, which were not significantly different from those of 91 and 80% for the 80 B recipients of B or O kidneys (Wilcoxon = 0.48; log-rank = 0.55). These data support the national trial for additional OPOs to voluntarily allocate A2 and A2B kidneys preferentially to B waiting list candidates, thus increasing access of blood group B patients to renal transplantation.

Non-medical factors influencing access to renal transplantation

“…Similarly, transplant candidates with blood group types B and O wait approximately twice as long as individuals with blood group A and four times as long as people with blood group AB [6]. Since most African Americans with ESRD have blood types B or O, this might further decrease their access to donor kidneys [43,53]. In 2002, the UNOS (United Network of Organ Sharing) implemented the elimination of the priority of HLA-B locus matching from kidney allocation, in order to promote equity in organ allocation by increasing the likelihood of deceased donor transplantation in minority patients [54].…”

Kidney and Pancreas Transplantation in the United States, 1995–2004

“…Increased use of blood group A2 and A2B kidneys in blood group B registrants could potentially reduce waiting times for blood group B registrants (4). The median time to transplant for registrants with a previous organ transplant is nearly twice as long as that for registrants waiting for a first transplant, likely reflecting sensitization and the presence of comorbidities.…”

Human leukocyte antigen in the allocation of kidneys from cadaveric donors in the United States

“…In an attempt to increase the rate of transplantation in blood group B candidates, the UNOS Board of Directors recently approved the use of a time-limited voluntary allocation variance enabling the transplantation of blood group A 2 and A 2 B cadaveric kidneys into blood group B recipients. Published reports have shown that blood group A 2 kidneys can be successfully transplanted into blood group B recipients, especially if they have low-titer anti-A antibodies (3). Performing this type of ABO incompatible transplant can increase the transplant rate of patients with blood group B (3).…”