Cross-reactive group matching does not lead to a better allocation and survival of donor kidneys

Background. In cadaveric renal transplantation HLA-A, -B, -DR matching of d onor and recipient is beneficial for graft survival. However, allocation ba sed on HLA matching seems to favor recipients with more frequently occurrin g HLA antigens, In this study we investigated whether matching on the basis of cross-reactive groups (CREGs), defined according to the United Network for Organ Sharing (UNOS), would be a good alternative for the allocation of kidneys without negatively influencing graft survival. Theoretically, this approach would provide more recipients with an immunologically well-matche d donor organ. Methods. The influence of CREG matching on graft survival was studied in un ivariate analyses using the Eurotransplant database. Results. No beneficial effect of CREG matching was observed, whereas a sign ificant HLA matching effect was observed in the 0 CREG mismatched donor/rec ipient combinations. Only in the small subgroup with 1 MM for HLA-A, -B and 0 MM for HLA-DR, a significantly better survival was observed, when this m ismatch belonged to the 0 or 1 MM CREG group versus two or more MM CREG gro up. However, this subgroup concerns only 8% of the transplants performed. Conclusions. In contrast to other reports, our study showed that HLA matchi ng is by far more beneficial than CREG matching. In the homogenous Eurotran splant population, adjusting the matching criteria toward CREG matching wou ld not lead to an improved graft survival.