The new kidney allocation system-who are we penalizing?

Abstract

The new kidney allocation system implemented at the end of 2014 attributes additional allocation points to sensitized patients using a sliding cPRA scale. In addition patients with > 98% cPRA receive regional/national allocation priority due to their high level of sensitization. Unfortunately,the new allocation system does not allow for the input of HLA-DQA and HLA-DP unacceptable antigens for the computation of cPRA. To assess the number of patients affected by the lack of programming for HLA-DQA and -DP, we reviewed the antibody data of our adult kidney waitlist population composed of 485 patients. We found that 7.6% of our patients had HLA-DP and/or HLA-DQA antibodies with MFI values > 3000 for which they were not receiving additional allocation points due to our inability to enter HLA-DQA and -DP specificities as unacceptable antigens. The vast majority of the affected patients (86.5%) had HLA-DP antibodies and cPRA of 98%. In fact 75.7% of patients with HLA-DQA or HLA-DP antibodies had cPRA of 98% while 24.3% had cPRA > 98% and thus were eligible for regional/national priority. Our gathered data strongly advocates the implementation of new allocation software allowing for the listing of HLA-DQA and HLA-DP unacceptable antigens and for computation of these unacceptable antigens in the cPRA. Per OPTN data as of 4/22/15 there were 123,193 people waiting for a kidney transplant in the US. Using our center specific data on a national scale, it means that 9300 people are not receiving allocation points for unacceptable antigens against HLA-DP and/or -DQA. Our data also supports the implementation of mandatory typing of donors for HLA-DP and DQA since 24.3% of patients with HLA-DQA and -DP antibodies have cPRA > 98%. Mandatory typing of donors for HLA-DP and -DQA would allow for faster organ allocation and unnecessary shipment of organ for regional/national share to patient having unacceptable HLA-DQA or -DP antibodies.