Tubular MAG3 Extraction Rate is a Predictor of Short-Term and Long-Term Outcome After Kidney Transplantation: A Prospective Observational Study.

Abstract

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. 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. 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. 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.