Eplet-based virtual PRA increases transplant probability in highly-sensitized patients

Background: The reduced access of highly-sensitized (HS) patients to kidney transplantation (KTx) is one of the major challenges for transplant community. Therefore, the aim of our study was to estimate the impact of three different vPRA calculations, assessed traditionally and using eplet-based analysis, in donor offers.

Methods: At 01-01-2020, 157 HS patients are waitlisted for deceased donor KTx and were included in this study. Total vPRA (vPRAt) was calculated considering all patient allosensitization history, using 1 k MFI cut-off. Current vPRA (vPRAc) refers only to the last year SAB assays, using 1 k MFI cut-off. For eplet vPRA (vPRAe) every SAB assay was analyzed by HLAMatchmaker and HLAfusion software. Matching runs have been performed taking vPRA calculation as unacceptable antigens (UAs).

Results: All patients had at least one previous sensitizing event and patients with 100% vPRA were predominantly candidates for retransplantation (P < 0.001), had higher PRA-CDC (P < 0.001), and longer dialysis vintage waiting time (P < 0.001). Inter-group movement analysis between vPRA measures showed that 70 (45%), 124 (79%) and 80 (51%) patients were reclassified to a lower group when considering vPRAt to vPRAc, vPRAt to vPRAe and vPRAc to vPRAe, respectively. The median percentage of change in estimated number of match runs needed for 95% probability of finding an acceptable donor was significantly more pronounced by increasing vPRAt intervals, when considering the reclassification from vPRAt to vPRAe (P < 0.001) or vPRAc to vPRAe (P = 0.045), while from vPRAt to vPRAc it was not (P = 0.899).

Conclusions: Our study demonstrated that the use of total or current vPRA calculations are impairing HS patients, by decreasing transplant probability, leading to dramatically longer waiting times, when compared to eplet based vPRA.