The Impact of Nonidentical ABO Deceased Donor Kidney Transplant on Kidney Utilization

Background: Blood type AB kidney transplant candidates have the shortest waiting times, yet the current allocation system allows allocation of type A donor kidneys to type AB recipients. Study Design: United Network for Organ Sharing/Organ Procurement and Transplantation Network data between 1995 and 2004, retrospective observational study. Setting & Participants: 189,773 candidates listed for kidney-only transplant; 93,604 kidneys transplanted, 15,580 kidneys discarded. Predictor: Blood type and demographic/clinical variables. Outcomes & Measurements: The extent of disparities in waiting times and concurrent differences in recovery, discard, live donor, and deceased donor transplant rates. Results: Blood type O, A, B, and AB candidates constituted 48%, 34%, 14%, and 4% of the list, respectively. Live donor transplant rates were lowest for type AB candidates (13.4% vs 15.5%, 16.8%, and 15.2%; P < 0.001). On multivariate analysis, type AB candidates had a 1.5-fold greater chance of receiving deceased donor kidney transplants than blood group A candidates (95% CI, 1.45-1.55). Recovery rates of type AB kidneys were similar to those for other blood types, whereas discard rates of type AB kidneys were significantly higher (adjusted OR [aOR], 1.71; 95% CI, 1.56-1.89) for both expanded criteria (aOR, 1.78; 95% CI, 1.52-2.09) and standard criteria donors (aOR, 1.67; 95% CI, 1.48-1.89). Limitations: Observational data. Potential confounding from unmeasured covariates. Conclusion: Allocation of type A kidneys to type AB recipients not only increases disparities in waiting times between these 2 groups; but concurrent with the shorter waiting times for type AB candidates, there is suboptimal use of type AB deceased donor and living donor kidneys.