Equitable allocation of HLA-compatible kidneys for local pools and for minorities

The methods used to allocate cadaveric kidneys in the United States have been criticized as being unfair to minorities because of an over-emphasis on HLA matching. We evaluated a new HLA-matching method that might alleviate this problem.

We used data from the United Network for Organ Sharing (UNOS) Kidney Transplant Registry to evaluate and project the outcome of cadaveric kidney transplantation. An HLA-matching method based on compatibility at 10 key amino acid residues of HLA-A and B molecules and a limited number of HLA-DR types was evaluated with use of the HLA types of the patients currently on the national waiting list and waiting lists in Los Angeles and Birmingham, Alabama.

With national kidney sharing, the projected 10-year rate of graft survival for transplants in which there were no HLA-A, B, or DR mismatches was 66 percent, as compared with 39 percent for transplants with more than two HLA-A, B, or DR mismatches. With local sharing, 43 percent of patients could be fully matched, and they had a projected 10-year graft-survival rate of 50 percent. When one HLA-DR mismatch was allowed, the projected 10-year graft survival was 46 percent, and 67 percent of patients waiting locally could receive such grafts. Even in Alabama, where 68 percent of the patients on the waiting list are black, 48 percent of waiting patients could obtain a matched kidney.

Inserting two new HLA-matching categories into the UNOS point system for cadaveric kidney allocation would increase the number of patients for whom matches could be found in local pools.