Abstract
PURPOSE: Kidney transplantation is the treatment of choice for end-stage kidney disease, but predicting short-term and long-term outcomes remains challenging. Noninvasive, widely available tools for early risk stratification are lacking. This study evaluated whether the tubular extraction rate (TER) of Tc-99m-MAG3 measured by renal scintigraphy can predict transplant outcomes. METHODS: In this prospective observational study, 488 kidney transplant recipients (2012-2022) underwent standardized Tc-99m-MAG3 scintigraphy on postoperative day 6 to quantify TER. Patients were stratified into quartiles. Primary short-term endpoints were delayed graft function (DGF) and length of hospital stay; the primary long-term endpoint was a composite of graft loss or death. Associations were assessed using multivariable logistic regression, generalized linear models, and Cox regression. RESULTS: Lower TER was significantly associated with older donor and recipient age, longer ischemia times, and higher DGF risk [adjusted OR 9.45 (95% CI: 4.31-20.72), lowest vs. highest quartile]. Low TER was linked to more dialysis sessions and longer hospitalization. During a median follow-up of 8.4 years, low TER was independently associated with increased risk of biopsy-proven rejection (HR: 4.23; 95% CI: 1.05-17.13), graft failure or death (HR: 3.87; 95% CI: 1.67-8.97). eGFR values over time were consistently higher in patients with higher TER values. CONCLUSIONS: The tubular extraction rate derived from MAG3 scintigraphy is a strong and independent predictor of both short-term and long-term outcomes after kidney transplantation. As a noninvasive and widely available diagnostic tool, it may facilitate early identification of high-risk transplant recipients and support personalized post-transplant care strategies.