ABO-adjusted calculated panel reactive antibody (cPRA): A unified metric for immunologic compatibility in kidney transplantation

• Type of Material: Article
• Authors: Loren Gragert, Tulane University; Matthew Kadatz, Vancouver Coastal Health Research Institute; James Alcorn, United Network for Organ Sharing, Richmond Virginia, USA; Darren Stewart, United Network for Organ Sharing, Richmond Virginia, USA; Doris Chang, Providence Hlth Res Inst; Jagbir Gill, University of British Columbia; Robert Liwski, Dalhousie University; Howard Gebel, Emory University; John Gill, University of British Columbia; James H Lan, Vancouver Coastal Health Research Institute
• Language: English
• Date: 2022-12-01
• Publisher: WILEY
• Publication Version: Final Published Version
• Copyright Statement: © 2022 The Authors. American Journal of Transplantation published by Wiley Periodicals LLC on behalf of The American Society of Transplantation and the American Society of Transplant Surgeons.
• License: Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International
• Final Published Version (URL): http://dx.doi.org/10.1111/ajt.17175
• Title of Journal or Parent Work: AMERICAN JOURNAL OF TRANSPLANTATION
• Volume: 22
• Issue: 12
• Start Page: 3093
• End Page: 3100
• Keywords: Transplantation; ABO incompatibility; ethics and public policy; DECEASED DONOR KIDNEYS; translational research/science; histocompatibility; immunogenetics; organ procurement and allocation; Life Sciences & Biomedicine; Surgery; panel reactive antibody (PRA); Science & Technology; organ allocation; registry/registry analysis; genetics
• Research Categories: Health Sciences, Pathology

Abstract

Implementation of the kidney allocation system in 2014 greatly reduced access disparity due to human leukocyte antigen (HLA) sensitization. To address persistent disparity related to candidate ABO blood groups, herein we propose a novel metric termed “ABO-adjusted cPRA,” which simultaneously considers the impact of candidate HLA and ABO sensitization on the same scale. An ethnic-weighted ABO-adjusted cPRA value was computed for 190 467 candidates on the kidney waitlist by combining candidate's conventional HLA cPRA with the remaining fraction of HLA-compatible donors that are ABO-incompatible. Consideration of ABO sensitization resulted in higher ABO-adjusted cPRA relative to conventional cPRA by HLA alone, except for AB candidates since they are not ABO-sensitized. Within cPRA Point Group = 99%, 43% of the candidates moved up to ABO-adjusted cPRA Point Group = 100%, though this proportion varied substantially by candidate blood group. Nearly all O and most B candidates would have elevated ABO-adjusted cPRA values above this policy threshold for allocation priority, but relatively few A candidates displayed this shift. Overall, ABO-adjusted cPRA more accurately measures the proportion of immune-compatible donors compared with conventional HLA cPRA, especially for highly sensitized candidates. Implementation of this novel metric could enable the development of allocation policies permitting more ABO-compatible transplants without compromising equity.