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

Overview

This retrospective cohort study evaluated kidney transplantation outcomes from donors aged 65 years and older with and without acute kidney injury (AKI) to determine whether graft safety and efficacy are comparable between groups. The analysis encompassed 685 kidney transplant recipients from three German transplant centers between 2006 and 2021, with 183 recipients receiving organs from AKI donors and 502 from non-AKI donors. AKI was classified according to KDIGO criteria, with the majority of AKI cases classified as stage 1 (81.6% of AKI cohort).

Methods and approach

The study employed a retrospective cohort design comparing transplantation outcomes stratified by donor AKI status. Primary and secondary endpoints included death-censored graft survival, overall graft survival, patient survival up to 7 years, estimated glomerular filtration rate (eGFR) trajectories through 5 years, incidence of delayed graft function, and biopsy-proven acute rejection. Statistical analysis utilized Kaplan-Meier survival estimates and multivariable Cox proportional hazards regression to adjust for established graft survival risk factors. Follow-up extended to 7 years post-transplantation.

Results

Delayed graft function occurred at identical rates between AKI and non-AKI recipient groups (32.8% vs. 32.8%, p=1.0). Death-censored graft survival at 7 years demonstrated no significant difference between AKI and non-AKI cohorts (59.0% versus 61.3%, p=0.87). Median eGFR at 12 months was 33.8 mL/min/1.73 m² (interquartile range 27.3-44.2) in the AKI group and 35.5 mL/min/1.73 m² (interquartile range 26.3-44.8) in the non-AKI group (p=0.79). Multivariable Cox regression analysis confirmed these findings remained statistically equivalent after adjustment for known graft survival risk factors, with comparable acute rejection rates between groups.

Implications

The findings indicate that carefully selected recipients of kidneys from elderly donors (≥65 years) with predominantly mild AKI (KDIGO stage 1) experience graft outcomes equivalent to recipients of kidneys from elderly donors without AKI. Short-term graft function and long-term allograft survival do not demonstrate compromise in the AKI cohort, suggesting that donor AKI status alone should not constitute a contraindication to organ utilization in this age group when appropriate selection criteria are applied. These results provide evidence supporting the expansion of the elderly deceased donor pool through the utilization of AKI organs, potentially increasing graft availability without sacrificing allograft quality or longevity.