Early Allograft Biopsy in Delayed Graft Function

Background: Delayed graft function (DGF) is a common complication after kidney transplant (KT) associated with decreased allograft function and survival. Diagnostic kidney biopsy is of particular interest as it may distinguish different etiologies of DGF. We aimed to clarify the role of early kidney biopsy by analyzing clinical and histologic characteristics of early kidney biopsy cases and its impact on outcomes. Methods: Retrospective data was obtained from all adult KT or kidney-pancreas recipients at the University of Chicago 1/2020-2/2024. Some patients had >1 KT during the study. We compared DGF cases with early biopsies performed within the first 60 days posttransplant to the remaining DGF cases with biopsies done later or not at all. Logistic models were constructed for early biopsy, and graft loss and death at 1 year, and linear regression was used for eGFR at 1 year. Results: DGF occurred in 159 transplants. Mean age was 55.3±12.6 years, 38.3% were female, and 75.5% were Black. Median dialysis vintage was 4.3 (1.6-6.4) years; median cold ischemia time (CIT) was 17.8 (10.5-23.2) hours. Mean kidney donor profile index (KDPI) was 53±26%. Calculated panel reactive antibody (cPRA) was 0% in 68.5% and >85% in 20.7% of patients. 19.5% had a prior KT. Early kidney biopsy was more likely performed among those with younger age (OR=1.35 per 10 years, 95%CI=1.02-1.78, P=0.03), shorter CIT (OR=1.14, 95%CI=1.09, 1.20 per hour, P<0.001), shorter dialysis vintage (OR=1.23, 95%CI=1.08, 1.40, P = 0.002), presence of donor-specific antibodies (OR=5.02, 95%CI=1.89, 13.3, P<0.001) and cPRA>85% (OR=2.80, 95% CI=1.24, 6.34, P<0.001). Early biopsy was associated with 1-year graft loss (OR=6.17 (95%CI=1.7-21.6, P=0.005) and more eculizumab (OR= 7.24 (95%CI=1.3-38.8, P=0.02). Among surviving allografts, early biopsy was not associated with significantly lower eGFR at 1 year (Δ= -0.9±3.6 ml/min/1.73m2, P=0.8). Conclusion: Early biopsy among KT patients with DGF was more likely performed among those with high immunological risk, and was associated with increased use of eculizumab and increased 1-year graft loss. However, their 1-year eGFR did not differ significantly from the other DGF cases. These data suggest early biopsy can be used to distinguish acute rejection and TMA resulting in prompt treatment and preservation of eGFR in surviving allografts.