Association Between the Early Postoperative Changes in Serum Brain Natriuretic Peptide and Allograft Survival After...

Background: Kidney transplantation (KT) improves survival and quality of life in patients with end-stage kidney disease; however, long-term allograft survival remains a major challenge. Brain natriuretic peptide (BNP), a biomarker of cardiorenal stress and volume status, may be associated with early postoperative physiological changes after KT. This study evaluated the association between early postoperative BNP changes and long-term allograft survival, and explored the potential role of BNP-derived parameters in relation to graft outcomes. Methods: This retrospective cohort study included adult recipients of deceased-donor KT between 2009 and 2018. Patients were categorized according to early graft function. Serum BNP levels were measured preoperatively and within postoperative 24 h, and the percentage increase (dBNP ratio) was calculated. Cox regression and receiver operating characteristic analyses were used to identify risk factors for graft failure and evaluate the discriminatory performance of BNP-derived biomarkers, respectively. Results: Among the 179 recipients, postoperative BNP levels and dBNP ratios differed significantly across graft function groups, with higher values in delayed graft function. After multivariate adjustment, the dBNP ratio remained significantly associated with graft failure (hazard ratio, 1.16; 95% confidence interval, 1.10-1.21; p < 0.001). Additionally, the dBNP ratio demonstrated better discriminatory performance for graft failure compared with postoperative BNP alone (area under the curve, 0.815 vs. 0.596; p < 0.001), with an exploratory cutoff of approximately 18%. Recipients with a dBNP ratio ≥ 18% had poorer early graft function, lower longitudinal estimated glomerular filtration rates, and significantly reduced graft survival. Conclusions: An increased early postoperative dBNP ratio was significantly associated with adverse long-term kidney allograft outcomes. However, given the potential for residual confounding, these findings should be interpreted as associative and hypothesis-generating rather than predictive.