#3167 Factors associated with allosensitization from kidney allograft failure to retransplantation

Abstract Background and Aims Retransplantation is becoming more and more common and is for many patients the best renal replacement therapy after the failure of a first graft. Considering that allosensitization might prolong the time on the waiting list for a retransplantation, preventing it is essential. Which is the best maintenance immunosuppression after graft failure is still matter of debate. Method We conducted a retrospective single-centre study including kidney transplanted recipients (KTR) who underwent a kidney retransplantation at the University Hospital of Zurich between 2012 and 2023. We analysed which factors and especially which kind of maintenance immunosuppression after allograft failure could affect allosensitization. Results In our cohort 129/1040 KTRs (12%) underwent retransplantation. Of these, 27/129 (20%) were living donations. The median waiting time for deceased-donor transplantation was 3.2 (1.2-3.6) years and 2.7 (0.6–6.2); 3.5 (2.4–4); 4.8 (2.1–5.7) and 6.0 (4.9–17) years for the blood groups A, O, B and AB respectively (P < 0.0001). Upon univariate analysis previous allograft nephrectomy was performed in 35/129 (27%) and was associated with a higher calculated panel reactive antibody: 90% vs. 29% (P < 0.0001). Interestingly, the use of an antimetabolite at the time of retransplantation was associated with a lower median cPRA (23% for azathioprine, 20% for MPA, and 88% for no antimetabolite; P < 0.0001). The same was true for the use of prednisone (24% vs. 66%, P = 0.02), but it was not true for the use of calcineurin inhibitors (P = 0.2). A higher urine volume was associated with a lower cPRA when compared to anuric KTRs (2% vs. 21% vs. 73% for normal volume, oliguria, and anuria, respectively). Moreover, haemodialysis was associated with a higher cPRA when compared to peritoneal dialysis or no dialysis (62% vs. 33% vs 1%, P = 0.02). First retransplantation was also associated with a lower cPRA if compared to a second or a third one (41% vs. 78% vs. 88%, P = 0.02). Surprisingly, we could not find a correlation between cPRA and time to retransplantation (r < 0.2, P = 0.3). Conclusion Our results suggest that many factors may influence allosensitization, some of which are modifiable. Nevertheless, time to retransplantation, in our cohort did not correlate with allosensitisation, suggesting that other factors as blood group might have a bigger influence on waiting time.