Extracellular Fluid Volume and Mortality after Kidney Transplantation

Background: High extracellular fluid volume (ECV) is associated with an increased risk of death in non-transplanted patients with chronic kidney disease (CKD). By contrast, both the determinants and the prognosis value of ECV in kidney transplant recipients (KTR) remain unclear.

Methods: We studied a bicentric prospective cohort of 2057 KTR, who underwent glomerular filtration rate measurement (mGFR) three months after transplantation. We calculated ECV from iohexol plasma disappearance curve and analyzed its association with patient's characteristics and outcomes.

Results: Mean ECV and mGFR were 14.6±2.6L/1.73m2 and 52±16mL/min/1.73m2, respectively. Multiple linear regression identified male gender, older donor and recipient ages, deceased donor, non-preemptive transplantation, diabetes, cardiac arrhythmia, heart failure, proteinuria and higher mGFR as independent factors associated with increased ECV. In multivariable cause specific cox analyzes, higher tertiles of ECV were associated with increased mortality [tertile 1 as reference; hazard ratio (95% confidence interval) for tertile 2: 1.65 (1.11-2.47); tertile 3: 1.80 (1.18-2.74)] but not graft loss. Increased ECV, 3 months after transplantation, was a predictor of reduced mGFR at 12 months after adjusting for three months mGFR and other confounding factors (β coefficient: -0.06; 95%CI [-0.09 to -0.02]).

Conclusion: an elevated ECV 3 months after KT is independently associated with increased mortality and decreased mGFR at 12 months, but not with graft loss.