Introduction: Patients with blood group O or B wait significantly longer for a kidney transplant than other groups. Blood group incompatible transplantation is widely accepted and in some centres, tailored desensitisation treatment is based on baseline anti-A or anti-B antibody titre. We studied the distribution of ABO-antibody titres, and have modelled the effect of altering UK Kidney allocation scheme (NKAS) to allow for patients with low titres to receive a deceased donor ABOi.

Methods: A prospective study of 237 adult patients on the waiting list for a transplant in 2 UK transplant centres. ABO-antibody measurements (anti-A and anti-B) were measured in a single laboratory. Based on the proportions of 'Low' (<1:16) anti-A or anti-B antibodies, 3 simulations were performed. Firstly, a baseline simulation (BASELINE) under current NKAS rules; secondly Simulation 1 (SIM1) permits ABO-I for adults with 'low' titres and Simulation 2 (SIM2) was SIM1 but restricted blood group B to A allocations to those with 000 HLA mismatches.

Results: Of the 237 patients, amongst blood group O 3% had 'Low' anti-A titres and 16% had 'low' anti-B; in blood group B 68% had 'low' anti-A; 75% of Blood group A had 'low' titres. Overall there was little difference in estimated numbers of patients transplanted. More blood group B recipients were transplanted in both simulations (p = 0.037 & 0.015). Median waiting time was reduced for blood group B recipients (BASELINE 2017 days; SIM1 1909 days; SIM2 1778 days, p=0.12) but increased for AB (SIM1 1570 days, SIM2 1584 days; BASELINE 1110 days p=0.01). There was a non-significant increase in the number of 000 HLA-mismatch allocations in both simulations compared to BASELINE (p = 0.19). In SIM1 59% of the Blood group B transplants were estimated to be ABOi, while SIM2 reduced this to 52%.

Discussion: Changing allocation in the UK to allow deceased donor ABOi would not change the number of transplants performed, but would redistribute allocation more fairly amongst blood groups, altering waiting times for accordingly. An unforeseen effect of allocation change increased the number of 000 mismatched transplants. Further work modelling the effect of applying these rules to predicted long-waiting recipients is planned.

CITATION INFORMATION: Manook M, Bradbury L, Osei-Bordom D, Sandhu B, Maggs T, Shaw O, Kessaris N, Shah S, Dorling A, Mamode N. Deceased Donor ABO-Incompatible Kidney Transplantation Has the Potential to Reduce Blood Group Disparity. Am J Transplant. 2016;16 (suppl 3).

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