Creating Options for Difficult-to-match Kidney Transplant Candidates.

BACKGROUND: Most transplantation centers recognize a small patient population that unsuccessfully participates in all available, both living and deceased donor, transplantation programs for many years: the difficult-to-match patients. This population consists of highly immunized and/or AB0 bloodgroup 0 or B patients. METHODS: To improve their chances, CIAT (Computerized Integration of Alternative Transplantation programs) was developed to integrate kidney paired donation, altruistic/unspecified donation and AB0 and HLA-desensitization. To compare CIAT with reality, a simulation was carried out, including all patients, donors and pairs that participated in our programs in 2015-2016. Criteria for inclusion as difficult-to-match, selected-Highly immunized patient (sHI) were: vPRA>85% and participating for 2 years in Eurotransplant Acceptable-mismatch program. sHI-patients were given priority and AB0i- and/or HLAi-matching with DSA-MFI<8000 were allowed. For long-waiting bloodgroup 0 or B patients AB0i matches were allowed. RESULTS: In reality, 90 alternative program transplantations were carried out: 73 compatible, 16 AB0i and 1 both AB0i-and-HLAi combination. Simulation with CIAT, resulted in 95 hypothetical transplantations: 83 compatible (including 1 sHI) and 5 AB0i combinations. Eight sHI patients were matched: 1 compatible, 6 HLAi with DSA-MFI<8000(1 also AB0i), and 1 AB0i match. Six/eight combinations for sHI-patients were CDC-XM negative. CONCLUSIONS: CIAT led to 8 times more matches for difficult-to-match sHI-patients. This offers them better chances because of a more favorable MFI profile against the new donor. Besides, more AB0 compatible matches were found for AB0i couples, while total number of transplantations was not hampered. Prioritizing difficult-to-match patients improves their chances without affecting the chances of regular patients.