Kidney transplant from donation after circulatory death: a novel pre-transplant combined clinico-pathological predictive score

Background: Kidney donation after circulatory death is a valid alternative to donation after brain death. However, ischemia–reperfusion injury can damage the graft and make it non-viable. The Karpinski score, currently used to evaluate kidney quality, does not account for this type of damage and is, therefore, insufficient for predicting expected functional recovery. Methods: Sixty-seven kidney biopsies from donors after circulatory death and seventy-two kidney biopsies from donors after brain death were analyzed histologically. A Karpinski score was assigned to all samples. Additionally, biopsies obtained from donation after circulatory death were reviewed for the presence of ischemia–reperfusion injury defined as brush border loss within the tubular epithelium as well as acute tubular injury. Clinical data were also retrieved and analysed, in an attempt to find a statistically significant correlation between histological/clinical findings and graft function. Results: The mean Karpinski scores of samples obtained on the occasion of donation after circulatory death and after brain death showed no significant difference. Ischemia–reperfusion injuries were two times more frequent in samples obtained after donation after circulatory death compared to donation after brain death. Statistical analysis revealed that a cutoff of 15% in brush border loss and 0.9 mg/dL in serum creatinine before death allowed to predict functional recovery, especially delayed functional recovery. A composite predictive score summing these two parameters was therefore created. Conclusions: Donation after circulatory death is associated with unique patological characteristics compared to donation after brain death and requires different considerations. This study proposes a simple and clinically applicable tool for predicting the delayed functional recovery in the case of kidneys donated after circulatory death; the novelty lies in combining morphological (brush border loss) and biochemical (serum creatinine before death) into a new predictive score that may provide support for pre-implantation decision-making and potentially improve transplant outcomes.