Subtype-Compatible (A2/A2B–>B) Transplantation Under KAS Increases Access 3-Fold for Blood Type B Patients, yet Very Few Candidates Are Listed as Eligible.
1UNOS, Richmond, VA
2Midwest Transplant Network, Westwood, KS
3Emory, Atlanta, GA
4Univ Hosp Case Med Ctr, Cleveland, OH.
Meeting: 2016 American Transplant Congress
Abstract number: 514
Keywords: African-American, Allocation, Kidney transplantation, Public policy
Session Information
Session Name: Concurrent Session: Kidney Waitlist Management and KAS Initial Results
Session Type: Concurrent Session
Date: Tuesday, June 14, 2016
Session Time: 4:30pm-6:00pm
Presentation Time: 5:18pm-5:30pm
Location: Veterans Auditorium
Background: Prior to the new kidney allocation system (KAS; 12/4/14), 8 OPOs participated in a voluntary policy variance permitting allocation of kidneys from subtype “A2” (A, non-A1) and “A2B” (AB, non-A1B) donors to eligible blood type B candidates, a biologically disadvantaged subgroup. With KAS, subtype-compatible transplantation (SCT) for eligible B candidates became available nationwide.
Methods: We examined trends in SCT prior (6/1/13-12/3/14) vs. post-KAS (12/4/14-8/31/15). Solitary, deceased donor kidney transplant (tx) rates per active patient year were compared post-KAS for B candidates listed as eligible vs. not eligible for SCT, accounting for changes in candidates' A2/A2B eligibility status. Relative risk of tx was approximated as the ratio of tx rates.
Results: Nationally, SCT increased from 1.9 to 9.0 transplants per month, a 5-fold post-KAS increase. B candidates listed as SCT eligible had tx rates of 0.45 (95% CI: 0.38, 0.55) – comparable to AB's (0.49; 0.45, 0.53) and 3.26 (2.69, 3.94) times higher than ineligible B candidates (0.14; 0.13, 0.15). (Fig 1) 
Still, on 8/31/15, just 2.5% (n=455) of B registrations at 44 programs were reported as eligible to receive these offers, despite published research suggesting 80% of B patients have sufficiently low anti-A titers to medically qualify and SCT outcomes are comparable to B-to-B tx. Post-KAS, SCT transplants have occurred at 27 kidney programs. Of blood type A kidney donors, OPOs reported 10% as having subtype A2.
Conclusions: Under KAS, B candidates listed as SCT eligible are not only permitted to receive A2/A2B offers, but they receive priority above other local adults for these kidneys. This has led to markedly higher tx rates for eligible candidates, yet few tx centers are currently participating. Increased awareness of this benefit and dissemination of strategies for reliable and cost-effective anti-A titer screening are needed for this aspect of KAS to reach its full potential.
CITATION INFORMATION: Stewart D, Cherikh W, Kucheryavaya A, Bryan C, Turgeon N, Aeder M. Subtype-Compatible (A2/A2B–>B) Transplantation Under KAS Increases Access 3-Fold for Blood Type B Patients, yet Very Few Candidates Are Listed as Eligible. Am J Transplant. 2016;16 (suppl 3).
To cite this abstract in AMA style:
Stewart D, Cherikh W, Kucheryavaya A, Bryan C, Turgeon N, Aeder M. Subtype-Compatible (A2/A2B–>B) Transplantation Under KAS Increases Access 3-Fold for Blood Type B Patients, yet Very Few Candidates Are Listed as Eligible. [abstract]. Am J Transplant. 2016; 16 (suppl 3). https://atcmeetingabstracts.com/abstract/subtype-compatible-a2a2b-b-transplantation-under-kas-increases-access-3-fold-for-blood-type-b-patients-yet-very-few-candidates-are-listed-as-eligible/. Accessed May 11, 2025.« Back to 2016 American Transplant Congress