Introduction: An ongoing challenge is the significant gap between organ supply and demand, which requires increased awareness for organ donation and for the decision-making process in accepting a graft. A donor offer requires careful consideration of various features, both donor and recipient, and despite the acute shortage of graft for kidney transplantation, each year more cadaveric kidneys are discarded because of unsuitability. The purpose of the study is to evaluate the effect of the difference of age and BMI between donor and recipient on single kidney transplantation (SKTx) outcome.

Method: We considered all patients underwent deceased SKTx from 2005 to 2021 at a single Center. The Δ-age was calculated as the difference between donor’s and recipient’s age. The Δ-BMI was calculated as the difference between donor’s and the recipient’s BMI. The effect of Δ-age and Δ-BMI was calculated, as odd ratio (OR), with respect to PNF, DGF, acute rejection, 3-month and 1-year eGFR. The ROC curve analysis was used to determine the cut-off value of significance of the Δ-age and Δ-BMI on the outcome.

Results: 354 SKTx were included in the analysis. The median Δ-age was 5 (range 0/11) years. The Δ-age was statistically associated to PNF (p=0.01), with an OR 1.11 (1.02-1.21), to DGF (p=0.03), with an OR 1.03 (1.00-1.05), and to acute rejection (p=0.0049), with an OR 1.05 (1.01-1.09). The Δ-age was also statistically associated to 3-month and 1-year e-GFR (p<0.001, est=-0.37 ±0.09 and p=0.004, est =-0.31 ±0.11). The cut-off value of Δ-age significatively associated to PNF was 19 years (AUC 0.74). Similar value related to DGF was 8 years (AUC 0.58) and that related to acute rejection was 5 years (AUC 0.65). The median Δ-BMI was 1.3 (range -1.2/4.5). The Δ-BMI was not statistically associated to any studied variables: PNF (p=0.25), DGF (p=0.55) acute rejection (p=0.37), 3-month e-GFR (p=0.35) and 1-year e-GFR (p=0.34).

Conclusions: In this study Δ-age >19 years is associated to a higher PNF rate and lower e-GFR so could be a useful parameter to evaluate in case of fragile recipient. Δ-age can be an easy parameter for immediate help in deciding if accepting or declining a donor according to the selected recipient.