The Eurotransplant Acceptable Mismatch (AM) program has been initiated 25 years ago in order to enhance transplantation of highly sensitized renal transplant candidates. Instead of avoiding unacceptable antigens, this program makes use of acceptable antigens, defined as antigens to which the patient has never formed antibodies, to predict a negative CDC crossmatch. Through addition of these acceptable antigens to the patient's own HLA phenotype, and mandatory shipment of a compatible organ to AM recipients, increased rates of transplantation of highly sensitized patients have been achieved. Here, we present long-term graft survival data on patients transplanted through the AM program.

We analyzed 10-year death censored graft survival of patients transplanted through regular allocation (Eurotransplant Kidney Allocation System: ET-KAS) and through the AM program. ET-KAS patients were subdivided according to the level of sensitization (0-5% PRA: non-sensitized, 6-85% PRA: sensitized, and >85% PRA: highly sensitized). Graft survival was compared to (highly sensitized) patients transplanted through the AM program.

AM patients had better 10-year graft survival compared to their highly sensitized counterparts transplanted through ET-KAS (P<0.001), whereas no statistically significant difference between AM patients and sensitized ET-KAS patients was observed. Non-sensitized patients had the best graft survival (P= 0.03). As the majority of AM patients received a re-transplant (71.2%) compared to a minority (14.9%) of ET-KAS patients (P<0.000001), we subsequently analyzed the 10-year graft survival of all re-transplant recipients. In this analysis, we found that AM patients had far superior graft survival compared to highly-sensitized ET-KAS patients (P=0.000003), and similar graft survival compared to sensitized (P= 0.05) and non-sensitized patients (P= 1.00). Multivariate analysis on all highly sensitized patients showed that the following parameters were independently affecting long-term graft survival: the number of HLA-A, -B, -DR mismatches, transplant period, donor sex and age, recipient age, as well as receiving a transplant through the AM program.

The AM program allows for increased rates of transplantation for highly sensitized patients while long-term graft survival of patients transplanted through the AM program is at least similar to that of patients transplanted through regular allocation.

CITATION INFORMATION: Heidt S, Witvliet M, Haasnoot G, Claas F. Highly Sensitized Patients Transplanted via the Eurotransplant Acceptable Mismatch Program Have Excellent Long-Term Graft Survival. Am J Transplant. 2016;16 (suppl 3).

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