Comparative Impact of Early Graft Function on Kidney Transplantation Outcomes According to Donor Types

Background: With the rise of high-risk living donor kidney transplantation, the impact of early graft function (EGF) on transplant outcomes remains unclear. Methods: In this retrospective multicenter study, we classified kidney transplantation recipients (KTRs) based on EGF and donor type. EGF within the first post-transplant week was classified as immediate graft function (IGF), slow graft function (SGF), or delayed graft function (DGF), with impaired EGF defined as SGF or DGF. The primary outcomes included biopsy-proven acute rejection (BPAR) within one year, death-censored graft failure (DCGF), and overall mortality. Results: Among 3,261 KTRs, 365 (11.2%) experienced impaired EGF, including 190 (5.8%) with SGF and 175 (5.4%) with DGF. In living donor KTRs, impaired EGF was significantly associated with an increased risk of one-year BPAR (aHR, 2.13; 95% CI, 1.33–3.39) and DCGF (aHR: 2.49, 95% CI: 1.29–4.82) but not mortality. Both SGF and DGF increased the risk of BPAR, while only DGF significantly elevated the risk of DCGF. In deceased donor KTRs, impaired EGF was associated with a higher risk of both DCGF (aHR, 2.18; 95% CI, 1.43–3.31) and mortality (aHR, 2.30; 95% CI, 1.52–3.49) with SGF and DGF demonstrating similar patterns. Notably, prolonged DGF (≥7 days) was linked to progressively worse outcomes. Conclusions: The impact of impaired EGF varies by donor type. In living donor KTRs, impaired EGF increased the risks of BPAR and DCGF, particularly in cases of DGF. In deceased donor KTRs, impaired EGF elevated the risks of DCGF and mortality but not BPAR, highlighting the need for tailored strategies to optimize EGF.