Impact of acute kidney injury in ≥65-year-old kidney donors on short- and long-term allograft outcomes

Background Kidney transplantation (KT) from elderly donors (aged ≥65 years) with acute kidney injury (AKI) remains controversial and these organs might be underutilized. To date, clear evidence supporting the safety of KT from donors with AKI exists solely for younger donor populations. We hypothesized that, when appropriately selected, graft survival and function in recipients of kidneys from AKI and non-AKI donors aged ≥65 years are comparable. Methods We conducted a retrospective cohort study analyzing KT outcomes from donors aged ≥65 years with and without AKI that were performed between 2006 and 2021 at three German transplant centers. AKI was defined according to KDIGO criteria. Death-censored graft survival, overall graft survival, patient survival up to 7 years, eGFR up to 5 years as well as incidence of delayed graft function and biopsy proven acute rejection were compared. Kaplan-Meier analyses and multivariable Cox regression were performed. Results Of 685 KT recipients, 183 received kidneys from AKI donors, and 502 from non-AKI donors. Most KTs were from donors with KDIGO stage 1 AKI ( n = 151; 81.6%). Delayed graft function occurred similarly often in AKI and non-AKI recipients (32.8% vs. 32.8%, p = 1.0). Death-censored graft survival was comparable between AKI and non-AKI groups (7 years: 59.0% vs. 61.3%; p = 0.87). Median eGFR at 12 months was 33.8 mL/min/1.73 m 2 (IQR 27.3, 44.2) in the AKI group and 35.5 mL/min/1.73 m 2 (IQR 26.3, 44.8) in the non-AKI group ( p = 0.79). These results remained unchanged after adjustment for known risk factors of graft survival in the multivariable Cox regression. Conclusion In this study, KT from ≥65-year-old donors with mostly mild AKI resulted in similar short and long-term graft survival and function compared to KT from ≥65-year-old donors without AKI. These findings support the utilization of AKI kidneys from elderly donors to expand the donor pool without compromising outcomes.