OR1 Scandiatransplant acceptable mismatch program; a bridge to transplanting the highly immunized kidney patients?

Abstract

Aim Scandiatransplant is the organ exchange organization for the Nordic countries. The number of highly immunized (HI) patients on the waiting list (WL) for deceased donor kidney transplant is steadily increasing and the HI patients wait longer than non-immunized patients do. The Scandiatransplant Acceptable Mismatch Program (STAMP) started in March 2009. The aim was to improve the probability for a HI patient to receive a suitable kidney graft from a deceased donor. Methods Patients are HLA typed at split level (HLA-A, B, C, DR, DQ) using serological or genomic techniques. The patients fulfill all the following criteria: (a) On WL >1 year, (b) HI, PRA ⩾80% based on CDC and/or solid phase assay, (c) HI in two consecutive samples over a period of more than 3 months, (d) Antibody reactivity against HLA cl I and/or II antigens, (e) The last tested sample drawn less than 3 months before acceptance. Eligible patients must have acceptable mismatches defined. We regard HLA antigens which the kidney patient has not developed clinical relevant antibodies (MFI > 1000) towards as acceptable. Upon registration, a transplantability score (TS) is calculated that take HLA antigens and AB0 blood group into account. The TS gives the likelihood of finding a suitable donor by counting the number of compatible donors in 1000 recently HLA typed deceased donors within Scandiatransplant. Results In the study period (March 2009–February 2015) 94/245 patients on the STAMP WL were transplanted, the mean waiting time for the transplanted patients being 137 days (2–721). In the same period, 4338/8583 patients on the ordinary WL were transplanted, with a mean waiting time of 421 days (0–2260). The TS ranged from 0 to 87/1000. The patients with a score ⩾10/1000 ( n = 40) were transplanted, with a mean waiting time of 40 days, while the patients with a TS n = 54) had a mean waiting time of 193 days. Ninety percent of the patients remaining on STAMP for more than a year have a TS Conclusion STAMP is a feasible and immunologically safe way to transplant HI patients. Patients with a TS