Time to Move on: HLA Matching Should Be Reconsidered in Modern Deceased Donor Kidney Allocation

HLA matching has been the cornerstone of deceased donor kidney allocation policies worldwide but can lead to racial inequity. Although HLA matching has been shown to improve clinical outcomes, the long-term impacts of nonallogenic factors are being increasingly recognized. This has led some transplant programs to include points for nonallogenic factors, for example, age. Our study looks at long-term graft and patient outcomes based on allocation cohorts rather than individual number of HLA mismatches.

Using the Australia and New Zealand Dialysis and Transplant Registry, we analyzed 7440 adult deceased donor transplant events from 2000 to 2018. Transplants were classified as HLA matched or nonmatched according to the OrganMatch score and the local allocation algorithms. Graft function was studied with linear mixed modeling and graft rejection with logistic and binomial regression. Time to graft failure and recipient survival were examined with Kaplan-Meier curve and Cox regression models.

Forty percent of transplants were HLA matched. Mean glomerular filtration rate was 1.76 mL/min/1.73 m² higher in the matched transplants (P < 0.001). Matched transplants had longer time to graft failure (15.9 versus 12.7 y; P < 0.001) and improved recipient survival (risk of death hazard ratio, 0.83; P = 0.003). Matched recipients spent less time on dialysis (28.1 versus 44.8 mo; P < 0.001), and this significantly contributed to the benefits seen in graft loss and recipient survival. Caucasian recipients were more likely to receive a matched transplant than non-Caucasians.

Matched transplants showed benefits in graft and recipient outcomes; however, some of these results were of small magnitude, whereas others seemed to be due in part to a reduction in time on dialysis. The benefit for the matched cohort came at the expense of the nonmatched cohort, who spent longer on dialysis and were more likely to be of a minority racial background.