Association between duration of delayed graft function, acute rejection and allograft outcome after deceased donor kidney transplantation

Prolonged duration of delayed graft function (DGF) may be associated with adverse allograft outcomes, but the association between threshold duration of DGF, acute rejection and long-term allograft loss remains undefined. We aimed to determine the impact of DGF duration on allograft outcomes and to assess whether this association was mediated by acute rejection. Using data from the Australian and New Zealand Dialysis and Transplant (ANZDATA) registry, Cox proportional modelling was used to determine the association between quartiles of DGF duration, acute rejection at 6 months and death-censored graft loss (DCGL). Mediation analysis was conducted to determine whether acute rejection was a causal intermediate between DGF and DCGL. Of 7668 deceased donor kidney transplants between 1997-2014, 1497 (19.5%) recipients experienced DGF requiring dialysis. The median (interquartile range) duration of DGF was 7(9) days, with 25% requiring dialysis for ≥14 days. Among recipients who had experienced DGF duration of 1-4 days, the adjusted HR for duration of 5-7, 8-13 and ≥14 days were 1.13 (95%CI 0.83-1.55;p=0.43), 1.44 (1.08-1.91;p=0.013), and 1.99 (1.50-2.65;p There was a direct dose-dependent effect between DGF duration and DCGL, with acute rejection explaining <10% of the effects between DGF duration and DCGL. Future research identifying other potential modifiable mediators that lies in the causal pathway between DGF duration and allograft loss is essential.