THE IMPACT OF HLA MISMATCHES ON THE SURVIVAL OF FIRST CADAVERIC KIDNEY-TRANSPLANTS

Background. The benefits of HLA-A, B, and DR matching of cadaveric kid ney grafts and recipients remain controversial when viewed from the pe rspective of social equity and graft survival. Methods. We estimated g raft survival using proportional-hazards techniques, adjusting for pat ient and donor characteristics, for a series of 30,564 Medicare patien ts receiving a first cadaveric kidney transplant between 1984 and 1990 . The effects of minimal achievable HLA mismatches and maximal matchin g on graft survival were estimated by simulated allocation of a sample of organs to a sample of 20,000 candidates for transplantation. Resul ts. The adjusted one-year graft survival was 84.3 percent for grafts w ith no mismatches and 77.0 percent for grafts with four mismatches. Na tional rationing of donor organs to achieve minimal mismatching and ma ximal matching could potentially decrease the average number of HLA mi smatches from 3.6 to 1.2, with a corresponding increase in the number of matches, As a consequence, projected five-year graft survival could potentially increase from 58.5 percent to 62.9 percent. This would be associated with a decrease in the proportion of kidneys allocated to black recipients from 22.2 to 15.0 percent. Conclusions, Under ideal c ircumstances, a policy of maximal matching of cadaveric renal transpla nts would increase five-year graft survival by a comparatively small 4 .4 percentage points, but the actual benefit is likely to be smaller.