Optimizing Living Donor Kidney Graft Function by Donor-Recipient Pair Selection

Longevity Matching for Living Donor Renal Transplantation

INTRODUCTION

This study identifies the effect of individual donor and recipient characteristics on graft survival in living-donor kidney transplantation (LDKT) using a recently described novel measure, kidney life years (KLYs).

MATERIALS AND METHODS

The Organ Procurement and Transplantation Network/United Network for Organ Sharing database was used to identify first-time kidney-only LDKT recipients between 1987 and 2020 who did not experience death with a functioning graft (DWFG) and were not missing relevant information (n = 87,290). Patient characteristics were evaluated using Cox and multiple regression analyses, with the dependent variable being KLYs. An equation for expected KLYs based on patient characteristics was created using regression coefficients. The equation was validated using bootstrapped Pearson correlations and then applied to the DWFG group for comparison.

RESULTS

Based on statistical significance from Cox and multiple linear regression analyses, 9 of the original 18 variables were selected for inclusion in the equation. Variables with notable impact included HLA match points (0.021 KLYs; 95% CI: [0.019,0.024]; P ≤ .001), Donor Age (-0.030 KLYs; 95% CI: [-0.035,-0.025]; P ≤ .001), and Donor African American Ethnicity (-2.356 KLYs; 95% CI: [-2.552,-2.159]; P ≤ .001). Equation validation was supported, given a negative correlation (r = -0.071; P ≤ .001) between expected KLY change and observed graft failure. Expected KLY change was found to be greater in those who eventually DWFG when compared with all other LDKTs (t = -5.735, P ≤ .001).

CONCLUSIONS

Increasing HLA match points may be more beneficial for graft longevity than minimizing donor age in comparisons using realistic between-donor differences. Additionally, greater average expected KLYs in those who ultimately DWFG may illustrate an opportunity for improved donor-recipient matching.

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.

Rethinking incompatibility in kidney transplantation

Donor/recipient incompatibility in kidney transplantation classically refers to ABO/HLA-incompatibility. Kidney paired donation (KPD) was historically established to circumvent ABO/HLA-incompatibility, with the goal of identifying ABO/HLA-compatible matches. However, there is a broad range of donor factors known to impact recipient outcomes beyond ABO/HLA-incompatibility, such as age and weight, and quantitative tools are now available to empirically compare potential living donors across many of these factors, such as the living donor kidney donor profile index (LKDPI). Moreover, the detrimental impact of mismatch at other HLA antigens (such as DQ) and epitope mismatching on posttransplant outcomes has become increasingly recognized. Thus, it is time for a new paradigm of incompatibility that considers all of these risks factors together in assessing donor/recipient compatibility and the potential utility for KPD. Under this new paradigm of incompatibility, we show how the LKDPI and other tools can be used to identify donor/recipient incompatibilities that could be improved through KPD, even for those with a traditionally "compatible" living donor.

Living-Donor Kidney Transplantation: Donor-Recipient Function Correlation

BACKGROUND

With the rising prevalence of living-donor kidney transplantation, evaluation of factors correlated with renal function in the donor-recipient pair constitutes a main goal for kidney transplantation clinicians. Our objective was to analyze the more relevant donor characteristics that contribute to donor and recipient estimated glomerular filtration rates (eGFR) after 1 year.

METHODS

We evaluated 48 consecutive donor-recipient pairs from our unit.

RESULTS

Mean donor age was 46 ± 11 years, with 71% being women. Mean recipient age was 35 ± 12 years, with 54% being men. Mean duration of donor hospitalization was 7 ± 2 days. Donor eGFR was 104 ± 11 mL/min/1.73 m² before donation and 70 ± 14 mL/min/1.73 m² at discharge. After 1 year, donor eGFR was 71 ± 12 mL/min/1.73 m² and recipient eGFR was 69 ± 10 mL/min/1.73 m². Donor eGFR <100 mL/min/1.73 m² before donation and age >50 years correlated with 17.7- and 8.9-fold increased risks, respectively, of recipient eGFR <60 mL/min/1.73 m² after 1 year. Donor being female, although statistically associated with worse graft function, compared with a male donor (P = .020), did not represent a significantly increased risk of recipient eGFR <60 mL/min/1.73 m². Higher donor body mass index (BMI) also associated with a lower kidney function for donors (P = .048). In multivariate linear regression to predict pairs' eGFRs after 1 year, only donor eGFR before donation and at discharge retained statistical significance (P ≤ .001 and P = .045, respectively).

CONCLUSIONS

Excluding unpredictable complications in the post-transplantation period, donor eGFR before donation, eGFR at discharge, and age were the best parameters to predict recipient and donor eGFRs after 1 year and can be used as a tool for managing expectations regarding the post-transplantation period.

HLA Matching Trumps Donor Age: Donor-Recipient Pairing Characteristics That Impact Long-Term Success in Living Donor Kidney Transplantation in the Era of Paired Kidney Exchange

BACKGROUND

We sought to identify donor characteristics influencing long-term graft survival, expressed by a novel measure, kidney life years (KLYs), in living donor kidney transplantation (LDKT).

METHODS

Cox and multiple regression analyses were applied to data from the Scientific Registry for Transplant Research from 1987 to 2015. Dependent variable was KLYs.

RESULTS

Living donor kidney transplantation (129 273) were performed from 1987 to 2013 in the United States. To allow sufficient time to assess long-term results, outcomes of LDKTs between 1987 and 2001 were analyzed. After excluding cases where a patient died with a functioning graft (8301) or those missing HLA data (9), 40 371 cases were analyzed. Of 18 independent variables, the focus became the 4 variables that were the most statistically and clinically significant in that they are potentially modifiable in donor selection (P <0.0001; ie, HLA match points, donor sex, donor biological sibling and donor age). HLA match points had the strongest relationship with KLYs, was associated with the greatest tendency toward graft longevity on Cox regression, and had the largest increase in KLYs (2.0 year increase per 50 antigen Match Points) based on multiple regression.

CONCLUSIONS

In cases when a patient has multiple potential donors, such as through paired exchange, graft life might be extended when a donor with favorable matching characteristics is selected.

Live Donor Renal Anatomic Asymmetry and Posttransplant Renal Function

BACKGROUND

Relationship between live donor renal anatomic asymmetry and posttransplant recipient function has not been studied extensively.

METHODS

We analyzed 96 live kidney donors, who had anatomical asymmetry (>10% renal length and/or volume difference calculated from computerized tomography angiograms) and their matching recipients. Split function differences (SFD) were quantified with technetium-dimercaptosuccinic acid renography. Implantation biopsies at time 0 were semiquantitatively scored. A comprehensive model using donor renal volume adjusted to recipient weight (Vol/Wgt), SFD, and biopsy score was used to predict recipient estimated glomerular filtration rate (eGFR) at 1 year. Primary analysis consisted of a logistic regression model of outcome (odds of developing eGFR>60 mL/min/1.73 m(2) at 1 year), a linear regression model of outcome (predicting recipient eGFR at one-year, using the chronic kidney disease-epidemiology collaboration formula), and a Monte Carlo simulation based on the linear regression model (N=10,000 iterations).

RESULTS

In the study cohort, the mean Vol/Wgt and eGFR at 1 year were 2.04 mL/kg and 60.4 mL/min/1.73 m(2), respectively. Volume and split ratios between 2 donor kidneys were strongly correlated (r = 0.79, P < 0.001). The biopsy scores among SFD categories (<5%, 5%-10%, >10%) were not different (P = 0.190). On multivariate models, only Vol/Wgt was significantly associated with higher odds of having eGFR > 60 mL/min/1.73 m (odds ratio, 8.94, 95% CI 2.47-32.25, P = 0.001) and had a strong discriminatory power in predicting the risk of eGFR less than 60 mL/min/1.73 m(2) at 1 year [receiver operating curve (ROC curve), 0.78, 95% CI, 0.68-0.89].

CONCLUSIONS

In the presence of donor renal anatomic asymmetry, Vol/Wgt appears to be a major determinant of recipient renal function at 1 year after transplantation. Renography can be replaced with CT volume calculation in estimating split renal function.

The Kidney Transplant Morbidity Index (KTMI): A Simple Prognostic Tool to Help Determine Outcome Risk in Kidney Transplant Candidates

Background

The Kidney Transplant Morbidity Index (KTMI) is a novel prognostic morbidity index to help determine the impact that pretransplant comorbid conditions have on transplant outcome.

Objective

To use national data to validate the KTMI.

Design

Retrospective analysis of the Organ Procurement and Transplant Network/United Network for Organ Sharing database.

Setting and Participants

The study sample consisted of 100 261 adult patients who received a kidney transplant between 2000 and 2008.

Main Outcome Measure

Kaplan-Meier survival curves were used to demonstrate 3-year graft and patient survival for each KTMI score. Cox proportional hazards regression models were created to determine hazards for 3-year graft failure and patient mortality for each KTMI score.

Results

A sequential decrease in graft survival (0 = 91.2%, 1 = 88.2%, 2 = 85.4%, 3 = 81.7%, 4 = 77.8%, 5 = 74.0%, 6 = 69.8%, and ≥7 = 68.7) and patient survival (0 = 98.2%, 1 = 96.6%, 2 = 93.7%, 3 = 89.7%, 4 = 84.8%, 5 = 80.8%, 6 = 76.0%, and ≥7 = 74.7%) is seen as KTMI scores increase. The differences in graft and patient survival between KTMI scores are all significant ( P < .001) except between 6 and ≥7. Multivariate regression analysis reveals that KTMI is an independent predictor of higher graft failure and patient mortality rates and that risk increases as KTMI scores increase.

Conclusion

The KTMI strongly predicts graft and patient survival by using pretransplant comorbid conditions; therefore, this easy-to-use tool can aid in determining outcome risk and transplant candidacy before listing, particularly in candidates with multiple comorbid conditions.

Size does matter: donor renal volume predicts recipient function following live donor renal transplantation

PURPOSE

With the now routine use of computerized tomography angiography with 3-dimensional reconstruction in the donor evaluation, renal volume can be easily determined using volume calculating software. We evaluated whether donor renal volume could predict recipient renal function.

MATERIALS AND METHODS

Clinical data of all donor and recipient pairs undergoing live donor kidney transplantation at our institution between January 2006 and October 2009 were reviewed. The volume of the kidney selected for transplant was determined using volume calculating software, and correlated to transplant recipient nadir and 1-year serum creatinine. Multivariate regression analysis was performed to adjust for demographic and clinical variables.

RESULTS

During the study period 114 patients underwent live donor renal transplantation. Recipient nadir and 1-year serum creatinine levels were significantly correlated with the volume of donated kidney even after adjusting for age, body mass index, body surface area and donor creatinine clearance. Kidney volume also retained significance after excluding recipients from analysis who experienced acute rejection episodes.

CONCLUSIONS

Larger kidney volumes calculated using 3-dimensional computerized tomography with volume calculating software are correlated with lower recipient nadir and 1-year serum creatinine levels.