A2/A2B Deceased Donor Kidney Transplantation Utilizing A2 Titers Improves Access to Kidney Transplantation: A Single Center Study

Rationale and Objective The option for A2/A2B deceased donor kidney transplantation was integrated into the kidney allocation system in 2014 to improve access for B blood group waitlist candidates. Despite excellent reported outcomes, center uptake has remained low across the United States. Here we examined the effect of implementing an A2/A2B protocol using a cut off titer of ≤ 1:8 for IgG and 1:16 for IgM on blood group B kidney transplant recipients at a single center. Study Design Retrospective observational study. Setting & Participants: Blood group B recipients of deceased donor kidney transplants at a single center from January 1, 2019 to December 2022. Exposure Recipients of deceased donor kidney transplants were analyzed based on donor blood type: A2/A2B vs. blood group compatible. Outcomes 1 year patient survival, death censored allograft function, primary non-function, delayed graft function, allograft function as measured by serum creatinine and eGFR at 1 year, biopsy proven rejection, and need for plasmapheresis. Analytical Approach Comparison between the A2/A2B and compatible groups were performed using the Fisher test or the Chi-Square test for categorical variables and the nonparametric Wilcoxon Rank-Sum Test for continuous variables. Results A total of 104 blood type B patients received a deceased donor kidney transplant at our center during the study period, 49 (47.1%) of which received an A2/A2B transplant. Waiting time was lower in A2/A2B recipients compared to blood group compatible recipients (57.9 months vs. 74.7 months, p=0.01). A2/A2B recipients were more likely to receive a donor after cardiac death (24.5% vs 1.8%, p<0.05) and experience delayed graft function (65.3% vs. 41.8%). There were no observed differences in the average serum creatinine or eGFR at 1-month, 3-months, and 1-year post kidney transplantation, acute rejection, or primary non-function. Limitations Single center study. Small cohort size limiting outcome analysis. Conclusions Implementation of an A2/A2B protocol increased transplant volumes of blood group B waitlisted patients by 83.6% while decreasing the waiting time for transplantation by 22.5% with similar transplant outcomes.