Donor factors predictive for poor outcomes of living donor kidney transplantation

Risk factors for delayed graft function and their impact on graft outcomes in live donor kidney transplantation

BACKGROUND

Delayed graft function (DGF) is a manifestation of acute kidney injury uniquely framed within the transplant process and a predictor of poor long-term graft function1. It is less common in the setting of living donor (LD) kidney transplantation. However, the detrimental impact of DGF on graft survival is more pronounced in LD2.

PURPOSE

To study the effects of DGF in the setting of LD kidney transplantation.

METHODS

We performed a retrospective analysis of LD kidney transplantations performed between 2010 and 2018 in the UNOS/OPTN database for DGF and its effect on graft survival.

RESULTS

A total of 42,736 LD recipients were identified, of whom 1115 (2.6%) developed DGF. Recipient dialysis status, male gender, diabetes, end-stage renal disease, donor age, right donor nephrectomy, panel reactive antibodies, HLA mismatch, and cold ischemia time were independent predictors of DGF. Three-year graft survival in patients with and without DGF was 89% and 95%, respectively. DGF was the greatest predictor of graft failure at three years (hazard ratio = 1.766, 95% CI: 1.514-2.059, P = 0.001) and was associated with higher rates of rejection (9% vs. 6.28%, P = 0.0003). Among patients with DGF, the graft survival rates with and without rejection were not different.

CONCLUSION

DGF is a major determinant of poor graft functional outcomes, independent of rejection.

K121Q polymorphism in the Ectonucleotide Pyrophosphatase/Phosphodiesterase 1 gene is associated with acute kidney rejection

The identification of risk factors for acute rejection (AR) may lead to strategies to improve success of kidney transplantation. Ectonucleotidases are ectoenzymes that hydrolyze extracellular nucleotides into nucleosides, modulating the purinergic signaling. Some members of the Ectonucleotidase family have been linked to transplant rejection processes. However, the association of Ectonucleotide Pyrophosphatase / Phosphodiesterase 1 (ENPP1) with AR has not yet been evaluated. The aim of this study was to evaluate the association between the K121Q polymorphism of ENPP1 gene and AR in kidney transplant patients. We analyzed 449 subjects without AR and 98 with AR from a retrospective cohort of kidney transplant patients from Southern Brazil. K121Q polymorphism was genotyped using allelic discrimination-real-time PCR. Cox regression analysis was used to evaluate freedom of AR in kidney transplant patients according to genotypes. Q allele frequency was 17.6% in recipients without AR and 21.9% in those with AR (P = 0.209). Genotype frequencies of the K121Q polymorphism were in Hardy-Weinberg equilibrium in non-AR patients (P = 0.70). The Q/Q genotype (recessive model) was associated with AR (HR = 2.83, 95% CI 1.08–7.45; P = 0.034) after adjusting for confounders factors. Our findings suggest a novel association between the ENPP1 121Q/Q genotype and AR in kidney transplant recipients.

Tubular maximum phosphate reabsorption capacity in living kidney donors is independently associated with one-year recipient GFR

The donor glomerular filtration rate (GFR) measured before kidney donation is a strong determinant of recipient graft outcome. No tubular function markers have been identified that can similarly be used in donors to predict recipient outcomes. In the present study we investigated whether the pre-donation tubular maximum reabsorption capacity of phosphate (TmP-GFR), which may be considered a functional tubular marker in healthy kidney donors, is associated with recipient GFR at 1 yr after transplantation, a key determinant of long-term outcome. We calculated the pre-donation TmP-GFR from serum and 24-h urine phosphate and creatinine levels in 165 kidney donors, and recipient ¹²⁵I-iothalamate GFR and eGFR (CKD-EPI) at 12 mo after transplantation. Kidney donors were 51 ± 10 yr old, 47% were men, and mean GFR was 118 ± 26 ml/min. The donor TmP-GFR was associated with recipient GFR 12 mo after transplantation (GFR 6.0 ml/min lower per 1 mg/dl decrement of TmP-GFR), which persisted after multivariable adjustment for donor age, sex, pre-donation GFR, and blood pressure and other potential confounders. Results were highly similar when eGFR at 12 mo was taken as the outcome. Tubular damage markers kidney injury molecule-1 and neutrophil gelatinase-associated lipocalin were low and not associated with recipient GFR. A lower donor TmP-GFR before donation, which may be considered to represent a functional measure of tubular phosphate reabsorption capacity, is independently associated with a lower recipient GFR 1 yr after transplantation. These data are the first to link donor tubular phosphate reabsorption with recipient GFR post-transplantation.

Progression of urinary protein excretion after kidney transplantation: A marker for poor long-term prognosis

INTRODUCTION

Post-transplantation proteinuria is a risk factor for graft failure. A progressive decline in renal graft function is a predictor for mortality in kidney transplant patients.

OBJECTIVES

To assess the development and the progression of urinary protein excretion (UPE) in the first year post-transplant in recipients of kidney transplants and its effect on patient and graft outcomes.

MATERIALS AND METHODS

We analysed 1815 patients with 24-h UPE measurements available at 3 and 12 months post-transplant. Patients were divided based on their UPE level: below 300 mg, 300-1000 mg and over 1000 mg (at 3 and 12 months), and changes over time were analysed.

RESULTS

At 3 months, 65.7% had UPE below 300 mg/24 h, 29.6% 300-1000 mg/24 h and 4.7% over 1000 mg/24h. At one year, 71.6% had UPE below 300 mg/24 h, 24.1% 300-1000 mg/24 h and 4.4% over 1000 mg/24 h. In 208 patients (12%), the UPE progressed, in 1233 (70.5%) it remained stable and in 306 (17.5%) an improvement was observed. We found that the level of UPE influenced graft survival, particularly if a progression occurred. Recipient's age and renal function at one year were found to be predictive factors for mortality, while proteinuria and renal function were predictive factors for graft survival.

CONCLUSIONS

Proteinuria after transplantation, essentially when it progresses, is a marker of a poor prognosis and a predictor for graft survival. Progression of proteinuria is associated with poorer renal function and lower graft survival rates.

Impact of donor kidney function and donor age on poor outcome of living-unrelated kidney transplantation (KT) in comparison with living-related KT

Living-unrelated donors (LURD) have been widely used for kidney transplantation (KT). We retrospectively reviewed 779 patients who underwent living-donor KT from 2000 to 2012, to compare outcomes of 264 KT from LURD and 515 from living-related donors (LRD), and to identify risk factors for living KT. Median follow-up was 67 months. Mean donor age, total human leukocyte antigen (HLA) mismatches, and HLA-DR mismatches were higher, and mean estimated glomerular filtration rate (eGFR) was lower in LURD. Acute rejection (AR)-free survival (p = 0.018) and graft survival (p = 0.025) were lower for LURD than LRD, whereas patient survival rate was comparable. Cox regression analysis showed HLA-DR mismatches (OR 1.75 for one mismatch; OR 2.19 for two mismatches), recipient age ≤ 42 yr, and donor age > 50 yr were significant risk factors for acute rejection. For graft survival, AR and donor eGFR (OR 1.90, p = 0.035) were significant. We also identified significant impact of recipient age > 50 yr and diabetes for patient survival. However, KT from LURD was not a significant risk factor for AR (p = 0.368), graft survival (p = 0.205), and patient survival (p = 0.836). Our data suggest that donor eGFR and donor age are independent risk factors for clinical outcomes of living KT, which can be related with poor outcome of KT from LURD.

The Outcomes of Living Kidney Donation from Medically Complex Donors: Implications for the Donor and the Recipient

Living kidney donation is an important option for patients with end-stage renal disease (ESRD), and has improved life expectancy and quality for patients otherwise requiring maintenance dialysis or deceased-donor transplantation. Given the favorable outcomes of live donation and the shortage of organs to transplant, individuals with potentially unfavorable demographic and clinical characteristics are increasingly being permitted to donate kidneys. While this trend has successfully expanded the live donor pool, it has raised concerns as to which acceptance criteria are safe. This review aims to summarize the existing literature on the outcomes of transplantation from medically complex, living kidney donors, including both donor and recipient outcomes when available.