Factors affecting eGFR 5-year post-deceased donor renal transplant: analysis and predictive model

Prediction models for the recipients' ideal perioperative estimated glomerular filtration rates for predicting graft survival after adult living-donor kidney transplantation

Introduction

The impact of the perioperative estimated glomerular filtration rate (eGFR) on graft survival in kidney transplant recipients is yet to be evaluated. In this study, we developed prediction models for the ideal perioperative eGFRs in recipients.

Methods

We evaluated the impact of perioperative predicted ideal and actual eGFRs on graft survival by including 1,174 consecutive adult patients who underwent living-donor kidney transplantation (LDKT) between January 2008 and December 2020. Prediction models for the ideal perioperative eGFR were developed for 676 recipients who were randomly assigned to the training and validation sets (ratio: 7:3). The prediction models for the ideal best eGFR within 3 weeks and those at 1, 2, and 3 weeks after LDKT in 474 recipients were developed using 10-fold validation and stepwise multiple regression model analyzes. The developed prediction models were validated in 202 recipients. Finally, the impact of perioperative predicted ideal eGFRs/actual eGFRs on graft survival was investigated using Fine-Gray regression analysis.

Results

The correlation coefficients of the predicted ideal best eGFR within 3 weeks and the predicted ideal eGFRs at 1, 2, and 3 weeks after LDKT were 0.651, 0.600, 0.598, and 0.617, respectively. Multivariate analyzes for graft loss demonstrated significant differences in the predicted ideal best eGFR/actual best eGFR within 3 weeks and the predicted ideal eGFRs/actual eGFRs at 1, 2, and 3 weeks after LDKT.

Discussion

The predicted ideal best eGFR/actual best eGFR within 3 weeks and the predicted ideal eGFRs/actual eGFRs at 1, 2, and 3 weeks after LDKT were independent prognostic factors for graft loss. Therefore, the perioperative predicted ideal eGFR/actual eGFR may be useful for predicting graft survival after adult LDKT.

Dominant predictors of early post-transplant outcomes based on the Korean Organ Transplantation Registry (KOTRY)

Data for Asian kidney transplants are very limited. We investigated the relative importance of prognostic markers in Asian kidney transplants by using Korean Organ Transplantation Registry (KOTRY) cohort. Prediction models were developed by data-driven variable selection approach. The relative importance of the selected predictors was measured by dominance analysis. A total of 4854 kidney transplant donor-recipient pairs were analyzed. Overall patient survival rates were 99.8%, 98.8%, and 91.8% at 1, 3, and 5 years, respectively. Death-censored graft survival rates were 98.4%, 97.0%, and 95.8% at 1, 3, and 5 years. Biopsy-proven acute rejection free survival rates were 90.1%, 87.4%, and 87.03% at 1, 3, and 5 years. The top 3 dominant predictors for recipient mortality within 1 year were recipient cardiovascular disease history, deceased donor, and recipient age. The dominant predictors for death-censored graft loss within 1 year were acute rejection, deceased donor, and desensitization. The dominant predictors to acute rejection within 1 year were donor age, HLA mismatched numbers, and desensitization. We presented clinical characteristics of patients enrolled in KOTRY during the last 5 years and investigated dominant predictors for early post-transplant outcomes, which would be useful for clinical decision-making based on quantitative measures.

Ultrasound elastography correlations between anthropometrical parameters in kidney transplant recipients

Ultrasound elastography (USE) is a method to assess the stiffness of parenchymatous organs. Shear wave elastography (SWE) is considered to be the most suitable elastography method for the non-invasive kidney transplant (KTx) elasticity assessment. The aim of this study was to assess the implementability of SWE for the evaluation of kidney transplant elasticity measurement depending on the depth of an allograft, body mass index (BMI) and donor age. Secondly, to investigate the associations between SWE stiffness measurements and the clinical parameters. This cross-sectional prospective study involved consecutive 100 KTx patients were grouped according to time from transplantation and their BMI (in BMI<25 group the mean was 22.1±2.4, n=42 and in BMI≥25 group the mean BMI was 29.9±3.3, n=58). Mean estimated glomerular filtration rate was almost similar in both groups: <25 group 54.3 and ≥25 group 53.4 mL/min. Mean elastography results were found statistically different (p=0.006) BMI<25 (8.95±5.84 kPa) and BMI≥25 (5.95±3.16 kPa) groups. Significant correlation was found between SWE and the depth of the measurement (r=-0.4, p<0.05). The variations in USE stiffness values were smallest in patients group with lower BMI. In conclusion, we demonstrated that the non-invasive USE measurement stiffness result depends on a patient's BMI, the depth of renal allograft and donor age.

Renal Allograft Rejection: Noninvasive Ultrasound- and MRI-Based Diagnostics

To date, allogeneic kidney transplantation remains the best available therapeutic option for patients with end-stage renal disease regarding overall survival and quality of life. Despite the advancements in immunosuppressive drugs and protocols, episodes of acute allograft rejection, a sterile inflammatory process, continue to endanger allograft survival. Since effective treatment for acute rejection episodes is available, instant diagnosis of this potentially reversible graft injury is imperative. Although histological examination by invasive core needle biopsy of the graft remains the gold standard for the diagnosis of ongoing rejection, it is always associated with the risk of causing substantial graft injury as a result of the biopsy procedure itself. At the same time, biopsies are not immediately feasible for a considerable number of patients taking anticoagulants due to the high risk of complications such as bleeding and uneven distribution of pathological changes within the graft. This can result in the wrong diagnosis due to the small size of the tissue sample taken. Therefore, there is a need for a tool that overcomes these problems by being noninvasive and capable of assessing the whole organ at the same time for specific and fast detection of acute allograft rejection. In this article, we review current state-of-the-art approaches for noninvasive diagnostics of acute renal transplant inflammation, i.e., rejection. We especially focus on nonradiation-based methods using magnetic resonance imaging (MRI) and ultrasound.

The impact of donor and recipient weight incompatibility on renal transplant outcomes

BACKGROUND

Donor/recipient size mismatching and correlation to allograft outcome remains poorly defined. This study assessed the impact of donor body weight (DBW) to recipient body weight (RBW) ratio on allograft function and survival.

METHODS

A total of 898 deceased donor renal transplant recipients were included in the study. Patients were divided into quartiles depending on the ratio of DBW/RBW: Q1 (≤ 0.88), Q2 (0.89-1.00), Q3 (1.01-1.22) and Q4 (> 1.22). Donor and recipient characteristics were obtained from the national kidney transplant service database. Serum creatinine and estimated glomerular filtration rate (eGFR) at 1 and 5 years after transplant were compared.

RESULTS

Q4 patients had a higher eGFR 1 year post-transplant (median 59.5 ml/min, IQR 46.8-76.2) compared to Q1-Q3 which had median eGFRs of 54.3, 54.8 and 55.3 ml/min, respectively (p < 0.001). At 5 years post-transplant, there were modest differences in the eGFR across the four quartiles, Q1-4 with median eGFRs of 56.9, 61.1, 61.2 and 58.6 ml/min, respectively (p = 0.02). However, there were no significant differences in 1- and 5-year allograft survival between groups.

CONCLUSIONS

In the setting of deceased donor renal transplantation, mismatching of donor to recipient weight had no impact on 5-year allograft survival, but a low DBW/RBW ratio is modestly associated with lower eGFR.

Outcomes of kidney transplantation in Alport syndrome compared with other forms of renal disease

Introduction: Alport syndrome is an inherited renal disease characterized by hematuria, renal failure, hearing loss and a lamellated glomerular basement membrane. Patients with Alport syndrome who undergo renal transplantation have been shown to have patient and graft survival rates similar to or better than those of patients with other renal diseases.

Methods: In this national case series, based in Beaumont Hospital Dublin, we studied the cohort of patients who underwent renal transplantation over the past 33 years, recorded prospectively in the Irish Renal Transplant Registry, and categorized them according to the presence or absence of Alport syndrome. The main outcomes assessed were patient and renal allograft survival.

Results: Fifty-one patients diagnosed with Alport syndrome in Beaumont Hospital received 62 transplants between 1982 and 2014. The comparison group of non-Alport patients comprised 3430 patients for 3865 transplants. Twenty-year Alport patient survival rate was 70.2%, compared to 44.8% for patients with other renal diseases (p = .01). Factors associated with patient survival included younger age at transplantation as well as differences in recipient sex, donor age, cold ischemia time, and episodes of acute rejection. Twenty-year graft survival was 46.8% for patients with Alport syndrome compared to 30.2% for those with non-Alport disease (p = .11).

Conclusions: Adjusting for baseline differences between the groups, patients with end-stage kidney disease (ESKD) due to Alport syndrome have similar patient and graft survival to those with other causes of ESKD. This indicates that early diagnosis and management can lead to favorable outcomes for this patient cohort.

Imaging-based diagnosis of acute renal allograft rejection

Kidney transplantation is the best available treatment for patients with end stage renal disease. Despite the introduction of effective immunosuppressant drugs, episodes of acute allograft rejection still endanger graft survival. Since efficient treatment of acute rejection is available, rapid diagnosis of this reversible graft injury is essential. For diagnosis of rejection, invasive core needle biopsy of the graft is the "gold-standard". However, biopsy carries the risk of significant graft injury and is not immediately feasible in patients taking anticoagulants. Therefore, a non-invasive tool assessing the whole organ for specific and fast detection of acute allograft rejection is desirable. We herein review current imaging-based state of the art approaches for non-invasive diagnostics of acute renal transplant rejection. We especially focus on new positron emission tomography-based as well as targeted ultrasound-based methods.