Effect of HLA matching on renal transplant survival.

1. HLA matching had a significant impact on cadaveric renal allograft survival. The difference in graft survival rates between the best- and worst-matched recipients among the 30,139 first cadaver transplants was 11% at one year, 19% at 3 years, and a projected 32% at 10 years posttransplant (p < 001). 2. Kidneys with no HLA antigens mismatched to the recipient yielded a superior result compared with any other match level. The one- and 3-year graft survival rates were 89% and 83% at one and 3 years, respectively. Even a single HLA antigen mismatch resulted in substantially poorer survival rates of 84% and 72% at one and 3 years (p < 0.001, each comparison). Nevertheless, there was a stepwise decline in graft survival with increasing numbers of mismatched HLA antigens. 3. The number of HLA-matched first cadaver transplants performed has increased from 2% of the total in 1987 to 6% in 1992, as a result of the national 6-antigen-match sharing program instituted by UNOS in 1987 and expanded to include phenotypically matched kidneys in 1990. 4. The incidence of early graft rejection episodes correlated with the number of HLA antigens mismatched. Only 12% of the zero-mismatched recipients experienced early rejection, whereas 26% of those with 5 or 6 antigens mismatched had rejection episodes during the transplant hospitalization (p < 0.01). 5. Transplants performed at the top 20 United States centers (based upon multivariate ranking) showed a strong effect of HLA matching, especially with respect to long-term outcome. The survival difference between the best- and worst-match groups was 9% at one year, 16% at 3 years, and a projected 25% at 10 years (p < 0.05). 6. Similarly, the survival difference between the best- and worst-matched groups at the bottom 20 centers was 16% at one year, 22% at 3 years, and a projected 36% at 10 years (p < 0.01). The bottom 20 centers apparently placed more emphasis on matching. Transplants with fewer than 3 mismatched antigens accounted for 34% of first cadaver transplants in the bottom 20, compared with 26% at the top 20 centers. 7. When all 27 possible HLA-A,B,DR mismatch combinations were examined, those involving HLA-DR mismatches had a strong influence on graft outcome at 3 months, whereas those involving HLA-B mismatches had the most influence on long-term outcome. HLA-A-locus mismatches had the smallest effect on graft outcome.(ABSTRACT TRUNCATED AT 400 WORDS)