#569 Proenkephalin A 119-159 (penKid) for the early identification and risk stratification of delayed graft function following kidney transplantation

Abstract

Abstract Background and Aims Delayed graft function (DGF) frequently occurs following kidney transplantation, and prolonged duration of DGF adversely affects 1-year graft function and long-term graft survival. Recently, Proenkephalin A 119-159 (penKid) was shown to reflect kidney function and predict acute kidney injury (AKI) in critically ill patients. Given the similarities between DGF in transplanted and AKI in native kidneys, we hypothesized that penKid may aid in identifying and risk-stratifying DGF post-transplantation. Method In a prospective study of 159 consecutive kidney transplant recipients at Heidelberg University Hospital from November 2021 to July 2023, penKid was quantified using an immunoluminometric assay until patient discharge. DGF was primarily defined as the necessity for dialysis within 7 days post-transplant. Additionally, penKid was examined in the context of DGF severity, discriminating the different durations of post-transplant dialysis treatment. Similarly, penKid was assessed to differentiate uptake of graft function, defined as slow or immediate by a serum creatinine reduction ratio of pre-transplant and 7 days post-transplant levels of <0.7 and ≥0.7, respectively. Results DGF, defined as the need for dialysis within the first week post-transplant, occurred in 53/159 (33.3%) patients. penKid enabled the differentiation of patients with and without DGF from the first day post-transplant onward (P < 0.001, Fig. 1), and consistently outperformed SCr in discriminating DGF from no DGF at all time points studied (P < 0.001). Additionally, penKid allowed identification of DGF severity from the first day post-transplant (P < 0.001) and early differentiation between slow and delayed graft function (AUC 0.79 [95% CI 0.68-0.90]). In a multivariate model, delta penKid from pre-transplant to the first day post-transplant emerged as the strongest predictor for DGF (C index = 0.88). On the first day post-transplant, penKid, with a cut-off at 300 pmol/L, discriminated DGF from no DGF with a sensitivity of 95.1% (95% CI 83.9–98.7) and a specificity of 56.5% (95% CI 46.3–66.2). Conclusion penKid is a promising biomarker shown to accurately differentiate DGF from no DGF as early as the first day post-transplant and to predict DGF severity, allowing for earlier intervention in these at-risk patients. Due to its high discriminatory power to identify and predict DGF post-transplantation, penKid shows great potential to accompany future studies examining the occurrence of DGF in transplant programs, where DCD is introduced into practice, machine perfusion techniques are assessed, or in trials that assess potential therapeutic interventions in patients with DGF.