Summary of Kidney Disease: Improving Global Outcomes (KDIGO) Clinical Practice Guideline on the Evaluation and Care of Living Kidney Donors

Medical Suitability and Willingness for Living Kidney Donation Among Older Adults

RATIONALE & OBJECTIVE

The benefits of kidney transplantation compared with treatment with dialysis, including in older adults, are primarily limited by the number of donated kidneys. We studied the potential to expand the use of older living kidney donors.

STUDY DESIGN

Secondary analysis of the Berlin Initiative Study, a population-based cohort.

SETTING & PARTICIPANTS

2,069 adults aged≥70 years in Germany.

EXPOSURE

Age and sex.

OUTCOME

Suitability for living donation assessed by the absence of kidney-related exclusions for donation including albuminuria and low estimated glomerular filtration rate (eGFR) as well as absence of other medical exclusions. Willingness for living and deceased kidney donation assessed by participant survey.

ANALYTICAL APPROACH

Descriptive analysis.

RESULTS

Among the 2,069 participants (median age 80 years, 53% women, median eGFR 63mL/min/1.73m2), 93% had≥1 medical contraindication for living donation at study entry unrelated to eGFR or albuminuria. Using 2 published eGFR and albuminuria thresholds for donor acceptance, 38% to 54% of participants had kidney-related exclusions for donation. Among the 5% to 6% of participants with neither medical nor kidney-related exclusions for living donation at baseline, 11% to 12% remained suitable for donation during 8 years of follow-up. Willingness for living or deceased donation was high (73% and 60%, respectively).

LIMITATIONS

GFR was not measured, and medical exclusions unrelated to eGFR and albuminuria were assessed using a cohort database complemented by claims data.

CONCLUSIONS

One in 20 older adults were potentially suitable for living kidney donation, and willingness for living donation was high. Further studies are warranted to define the feasibility of expanding living kidney donation among older adults.

PLAIN-LANGUAGE SUMMARY

Although potentially beneficial, kidney transplantation remains infrequent among older adults aged≥70 years with kidney failure. Study evaluated the potential to increase living kidney donation among older adults, including their medical suitability as well as willingness to donate. Among 2,069 community-dwelling older adults (median age 80 years), 5% to 6% had no exclusion to donation. Among these individuals, 11% to 12% remained suitable for donation during 8 years of follow-up. Most exclusions were not related to eGFR and albuminuria. Willingness to living donation was high (73%). These findings highlight the potential benefits from expanding the pool of transplantable kidneys through the use of living donation in older adults.

Identifying the Views and Needs of Family Physicians on Providing Care to Living Kidney Donors: A Cross-Sectional Survey

Optimizing the long-term care and follow-up of living kidney donors (LKDs) has been challenging, and prior LKDs have reported suboptimal healthcare experiences. Long-term care of LKDs is largely undertaken by primary care practitioners such as family physicians (FPs). We conducted a cross-sectional survey of Canadian FPs (n = 151). In our sample, 21.9% of participants reported that ≥1 patient had expressed interest in becoming a LKD, and 39.9% provided care to prior LKDs. While 55.5% knew how to find information on living kidney donation, 75.5% reported that information was not available in their practice. Only a minority had formal training in living kidney donation (<5%), and self-reported knowledge was low (median = 3 [scale 1 = not strong to 10 = very strong]). Knowledge improved significantly with educational activities, resources, experience, and practice needs. Attitudes toward living kidney donation were generally favorable with 71.5% stating that FPs should be involved in post-donation care. Clinical care guidelines (78.8%) were the most desired resource, followed by clear communication and reliable contact at transplant centers. Our findings inform the transplant community of an avenue to optimize LKD care by better-supporting FPs, who provide care to LKDs. This may enhance data collection on LKD outcomes and potentially increase donation rates.

Fewer medullary pyramids in the living kidney donor associate with graft failure in the recipient

This study aimed to identify the parenchymal structural features by both CT and histology that associate with death-censored graft failure in recipients of living donor kidneys. We analyzed kidney recipients of ABO-compatible living donor kidneys from 2000-2020 with follow-up through 2023. Cortical volume and thickness, individual medullary pyramid volume and count, glomerular volume, nephrosclerosis, and nephron number were assessed by deep learning models applied to the predonation CT and by morphometric histology analysis from the biopsy at the time of transplantation. There were 3098 recipients followed a median 5 years with 346 graft failure events. In adjusted analyses, the only structural measures associated with graft failure were fewer medullary pyramids on CT and a higher fraction of interstitial fibrosis and tubular atrophy (IFTA) on histology. Having ≤15 pyramids donated occurred in 9% and was associated with a graft failure incidence of 2.5 per 100 person-years compared to 1.6 per 100 person-years in the 17% with ≥26 pyramids donated. Fewer medullary pyramids were associated with a lower 1-year eGFR, which mediated the subsequent risk of graft failure. IFTA >1% is also associated with graft failure. Medullary pyramid count is a potentially useful predonation prognostic biomarker for graft failure in transplant recipients.

Genetic Assessment of Living Kidney Transplant Donors: A Survey of Canadian Practices

Background

Kidney failure is a prevalent condition with tendency for familial clustering in up to 27% of the affected individuals. Living kidney donor (LKD) transplantation is the optimal treatment option; however, in Canada, more than 45% of LKDs are biologically related to their recipients which subjects recipients to worse graft survival and donors to higher future risk of kidney failure. Although not fully understood, this observation could be partially explained by genetic predisposition to kidney diseases. Genetic testing of potential LKDs may improve risk assessment and inform the safety of donation. The strategies to evaluate these donors are still evolving. In Canada, little is known about the practice of assessing for genetic conditions among LKDs.

Aim

The aim was to examine the Canadian practices regarding LKDs genetic assessment.

Methods

Questionnaires were sent to 23 Canadian adult transplant centers to examine their protocols for LKDs genetic assessment.

Design

The questionnaire comprised of 10 sections and 21 questions including case scenarios of different LKD encounters. Major domains of the survey addressed general demographics, information sharing practices, effect of mode of inheritance on candidacy decision, having a policy for LKD genetic evaluation, and case scenarios covering the following conditions: autosomal dominant polycystic kidney disease (ADPKD), Alport syndrome, Fabry disease, familial focal and segmental glomerulosclerosis (FSGS), atypical hemolytic uremic syndrome (aHUS), autosomal dominant tubulointerstitial kidney disease (ADTKD), sickle cell, and apolipoprotein L1 mutation (APOL1).

Participants

The questionnaire was sent to the living-donor assessment committee representative (nephrologist) in adult and pediatric kidney transplant centers across Canada.

Results

In total, 16 of 23 Canadian centers responded to the survey. Of the 8 surveyed genetic conditions, ADPKD, Alport syndrome, and aHUS were the most frequently encountered. More centers have specific policies for donor evaluation for ADPKD (25%) and aHUS (21.4%) vs none to very few for other genetic conditions. The most cited guidelines are Kidney Disease Improving Global Outcomes (KDIGO), Canadian Society of Nephrology/Canadian Society of Transplantation (CSN/CST), and the Canadian Blood Services' Kidney Paired Donation Protocol.

Conclusions

Canadian transplant centers follow a case-by-case approach rather than a standard protocol for genetic assessment of LKDs given that current guideline recommendations are based on expert opinion due to a lack of a reliable body of evidence. With the expected rise in utilization of the increasingly available genetic testing, early multidisciplinary assessment including medical geneticists has the potential to improve personalized management. Studies examining long-term donor and graft outcomes are needed to construct the basis for evidence-based recommendations and inform the safety of donations.

Isolated microhematuria in potential kidney donors: evaluating kidney biopsy findings with dipstick urinalysis and urine microscopy results

Background

Isolated microhematuria (IMH) can signal hidden glomerular disease, necessitating detailed evaluations for potential kidney donors, including kidney biopsies. The optimal strategy for deciding on kidney biopsies remains unclear. While the British Transplant Society supports dipstick analysis, KDIGO focuses solely on urine microscopy. This study explored the correlation between kidney biopsy outcomes and results from dipstick urinalysis and urine microscopy in potential kidney donors.

Methods

This retrospective study encompassed all potential kidney donors who received kidney biopsies following a positive urine dipstick result for IMH, irrespective of whether red blood cells (RBCs) were found on urine microscopy. We performed sensitivity and specificity analyses to assess the effectiveness of microscopy and dipstick urinalysis in identifying histological abnormalities in the kidney biopsies.

Results

Approximately 49% of potential donors-133 out of 271-who had kidney biopsies due to positive dipstick tests showed negative results in urine microscopy for RBCs. In total, 168 donor candidates, or 62%, had abnormal findings in their biopsies, with nearly half of those diagnosed with immunoglobulin A nephropathy having negative urine microscopy results. Furthermore, 58% of potential donors with negative urine microscopy results-77 out of 133-also exhibited abnormal biopsy findings. The urine microscopy test displayed a sensitivity of 54.2% (95% confidence interval 46.6-61.5) and a specificity of 54.4% (95% confidence interval 44.8-63.7) for detecting abnormal biopsy results.

Conclusion

This study highlighted a significant presence of donors with IMH with underlying glomerular lesions. Using urine microscopy showed limited sensitivity and specificity in identifying abnormal histopathological results. Relying solely on urine microscopy may miss critical pathologies like IgAN in prospective kidney donors. The persistence of IMH during dipstick urinalysis calls for kidney biopsy in potential donors. These findings suggest that our results be incorporated into future global guideline formulations.

Obesity-Related Kidney Disease in Bariatric Surgery Candidates

BACKGROUND

Obesity has a negative impact in kidney health. However, the hallmarks of kidney dysfunction in bariatric surgery candidates are poorly characterized. To address this knowledge gap, we used a propensity score-matched analysis to compare kidney lesion biomarkers in bariatric surgery candidates and living kidney donors.

METHODS

Bariatric surgery candidates attending a single center for obesity treatment were pair-matched for sex and age to potential living kidney transplant donors (PLKD) using a 1:1 nearest-neighbor approach (N = 400, n = 200/group). A 24-h urine collection was used to analyze proteinuria and creatinine clearance.

RESULTS

Patients with obesity (PWO) had higher creatinine clearance when compared to PLKD (143.35 ± 45.50 mL/min vs 133.99 ± 39.06 mL/min, p = 0.03), which was underestimated when correction for body surface area (BSA) was used (creatinine clearance corrected for BSA of 115.25 ± 33.63 mL/min/1.73 m2 in PWO vs 135.47 ± 35.56 mL/min/1.73 m2 in PLKD). Proteinuria was also higher in PWO compared to PLKD (139.82 ± 353.258 mg/day vs 136.35 ± 62.24 mg/day, p < 0.0001). Regression analysis showed that creatinine clearance was strongly correlated with proteinuria in PWO (HR 1.522, p = 0.005), but it was less evident in PLKD (HR 0.376, p = 0.001).

CONCLUSION

Hyperfiltration and disproportionate proteinuria are frequent in patients with obesity. Since hyperfiltration can be underestimated by adjusting creatinine clearance for BSA, this should not be used when evaluating kidney function in bariatric surgery candidates.

Expanding Opportunities for Living Donation: Recommendations From the 2023 Santander Summit to Ensure Donor Protections, Informed Decision Making, and Equitable Access

A strategic vision toward global convergence in transplantation must encourage and remove barriers to living organ donation and transplantation. Here, we discuss deliberations of a working group of the 2023 Santander Summit charged with formulating recommendations for the safe expansion of living donor kidney transplantation and living donor liver transplantation worldwide. Living donor kidney transplantation has grown to be the preferred treatment for advanced kidney failure. Living donor liver transplantation emerged more recently as a strategy to reduce waitlist mortality, with adoption influenced by cultural factors, regional policies, clinical team experience, and the maturity of regional deceased donor transplant systems. Barriers to living donor transplantation span domains of education, infrastructure, risk assessment/risk communication, and financial burden to donors. Paired donor exchange is a growing option for overcoming incompatibilities to transplantation but is variably used across and within countries. Effectively expanding access to living donor transplantation requires multifaceted strategies, including improved education and outreach, and measures to enhance efficiency, transparency, and shared decision making in donor candidate evaluation. Efforts toward global dissemination and vigilant oversight of best practices and international standards for the assessment, informed consent, approval, and monitoring of living donors are needed. Fostering greater participation in paired exchange requires eliminating disincentives and logistical obstacles for transplant programs and patients, and establishing an ethical and legal framework grounded in World Health Organization Guiding Principles. Sharing of best practices from successful countries and programs to jurisdictions with emerging practices is vital to safely expand the practice of living donation worldwide and bring the field together globally.

Understanding the Healthcare Needs of Living Kidney Donors Using the Picker Principles of Patient-centered Care: A Scoping Review

Living kidney donors (LKDs) undertake a complex and multifaceted journey when pursuing donation and have several unmet healthcare needs. A comprehensive understanding of these needs across their entire donation trajectory can help develop a patient-centered care model. We conducted a scoping review to synthesize empirical evidence, published since 2000, on LKDs' experiences with healthcare from when they decided to pursue donation to postdonation care, and what they reported as their care needs. We categorized them according to the 8 Picker principles of patient-centered care. Of the 4514 articles screened, 47 were included. Ample literature highlighted the need for (1) holistic, adaptable, and linguistically appropriate approaches to education and information; (2) systematic, consistent, and proactive coordination and integration of care; and (3) self-management and preparation to optimize perioperative physical comfort. Some literature highlighted the need for (4) better continuity and transition of care postdonation. Two key unmet needs were the lack of (5) a holistic psychosocial evaluation predonation and predischarge to provide emotional support and alleviation of fear and anxiety; and (6) access to specialty and psychosocial services postdonation especially when adverse events occurred. Limited literature explored the principles of (7) respect for patients' values, preferences, and expressed needs; and (8) involvement of family and friends as caregivers. We summarize several unmet healthcare needs of LKDs throughout their donation journey and highlight knowledge gaps. Addressing them can improve their well-being and experiences, and potentially address inequities in living kidney donation and increase living donor kidney transplantation.

Higher abdominal fat area associates with lower donor kidney function before and after living kidney donation

Central body fat distribution affects kidney function. Abdominal fat measurements using computed tomography (CT) may prove superior in assessing body composition-related kidney risk in living kidney donors. This retrospective cohort study including 550 kidney donors aimed to determine the association between CT-measured abdominal fat areas and kidney function before and after donor nephrectomy. Donors underwent glomerular filtration rate measurements (125I-Iothalamate, mGFR) before and 3 months after donation. Linear regression analyses with body surface area (BSA)-standardized and crude mGFR were performed to assess the association of height-indexed tomographic fat measurements with kidney function. In age-, and sex-adjusted analyses higher levels of total abdominal, visceral, subcutaneous, and intramuscular adipose tissue index were significantly associated with lower mGFR levels before donation (BSA-standardized mGFR: visceral adipose tissue index: Βeta=-0.11, p < 0.001, subcutaneous: Βeta=-0.10, p < 0.001, intramuscular: Βeta=-1.18, p < 0.001, total abdominal: Βeta=-0.07, p < 0.001). Higher tomographic abdominal fat is associated with lower BSA-standardized mGFR after donation and a greater decrease in mGFR between screening and 3 months post-donation. This study shows that CT-measured abdominal fat area is associated with kidney function before and after living kidney donation.

Dickkopf 3 as a New Monitoring Tool for Kidney Function After Living Kidney Donation

Background: Even today, a non-invasive biomarker to identify donors with enhanced risk for renal impairment is missing. Dickkopf 3 (DKK3) can cause tubulointerstitial fibrosis and is associated with rapid eGFR loss. The aim of our work was to analyze whether DKK3 can be used as a non-invasive alert marker for an increased risk of loss of kidney function in living kidney donors (LKDs). Methods: All donors who were examined between July 2022 and June 2023 (n = 117) were included. DKK3 was measured in the urine. The collected patient-related data were compared with parameters before donation. The study cohort was stratified by DKK3 values ( Collapse

Key Words

• DKK3
• living kidney transplantation
• non-invasive monitoring

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Affiliation(s)

Antonia Schuster Department of Nephrology, University Hospital Regensburg, Franz-Josef-Strauß-Allee 11, 93053 Regensburg, Germany
Louisa Steines Department of Nephrology, University Hospital Regensburg, Franz-Josef-Strauß-Allee 11, 93053 Regensburg, Germany
Bernhard Banas Department of Nephrology, University Hospital Regensburg, Franz-Josef-Strauß-Allee 11, 93053 Regensburg, Germany
Tobias Bergler Department of Nephrology, University Hospital Regensburg, Franz-Josef-Strauß-Allee 11, 93053 Regensburg, Germany Medical Clinic III-Nephrology, Hospital Ingolstadt, Krumenauerstr. 25, 85049 Ingolstadt, Germany

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Nested Semi-Transparent Isosurface Simulated Volume-Rendering (NESTIS-VR) - An efficient on-device rendering approach for Augmented Reality headsets increasing surgeon confidence of kidney donor arterial anatomy

BACKGROUND AND OBJECTIVE

Volume-renderings of computed tomography or magnetic resonance angiograms (MRAs) are routinely used by surgeons in the preoperative assessment of vascular anatomy in kidney donors. Stereoscopic headsets (OST-HMD) like Microsoft HoloLens allow intuitive interaction with three-dimensional content for more intuitive comprehension, but do not allow real-time ray-casting volume-rendering of medical volume datasets on-device due to computational limitations.

METHODS

We introduce NEsted Semi-Transparent Isosurface Simulated Volume-Rendering (NESTIS-VR), as an on-device alternative to ray-casting volume-rendering and developed an application for HoloLens to render kidney donor MRAs with interactive control of fundamental rendering parameters. We compared NESTIS-VR with current standard pre-calculated 2D ray-cast volume-renderings in an observational study with 2 expert kidney transplant surgeons, measuring their confidence in pre-operatively assessing the kidney pedicle arterial anatomy in 20 potential donors. We also compared it against other 3D rendering techniques to understand which features contributed most to any improvements.

RESULTS

Real-time stereoscopic three-dimensional (3D) NESTIS-VR in Augmented Reality significantly improves surgeons' confidence compared with pre-calculated conventional two-dimensional (2D) ray-casting volume-rendered images (p = 0.0415/p = 0.00003). 2D non-stereoscopic NESTIS-VR was significantly superior to pre-calculated 2D ray-casting volume-rendered images for both surgeons (p = 0.044/p = 0.0003). Single isosurface 2D rendering was significantly superior than pre-calculated 2D volume-rendered images for one surgeon. There was no significant difference between binocular 3D display over 2D views with NESTIS-VR or between constrained and unconstrained vantage points for 2D viewing.

CONCLUSION

NESTIS-VR provides a new approach to rendering medical datasets in computationally limited OST-HMD headsets and significantly increases surgeons' confidence of kidney donor arterial anatomy. The principal confidence benefit arises from providing surgeons interactive control over rendering parameters compared to pre-calculated renderings at preset parameters whilst rendering on-device and keeping the OST-HMD untethered from a workstation.

Renal function outcomes in living kidney donors in a transplant center in Colombia

Introduction

Living kidney donation is currently low in Colombia, and this is associated with the lack of knowledge of the risks and renal function outcomes of potential donors; there are no studies that evaluate these outcomes. The objective of this study is to evaluate the outcomes of renal function, the incidence of metabolic diseases, arterial hypertension, as well as the finding of albuminuria and/or proteinuria in living kidney donors with a 2-year follow-up post donation.

Methods

Observational study in living kidney donor patients, in which renal function outcomes were evaluated between the predonation period and up to 24 months postdonation.

Results

Ninety-one patients were included, with a median predonation glomerular filtration rate of 98 ml/min/1.73 m2, interquartile range (90.5-109), and 24-month postdonation of 66.3 ml/min/1.73 m2 interquartile range (57.9-75). A total of 60.26% of the population was in stage 2 at the end of follow-up and no patient had a glomerular filtration rate less than 30 ml/min/1.73 m2 or required renal support therapy.

Conclusion

A living donor evaluation process based on risk factor stratification and adequate assessment of renal function was found to generate safe renal function outcomes both in the perioperative period and in medium- and long-term follow-up.

Pregnancy Outcomes in Living Kidney Donors: Protocol of a Population-Based Cohort Study in Three Canadian Provinces

Background

A substantial proportion of living kidney donors are women of childbearing age. Some prior studies report a higher risk of gestational hypertension and pre-eclampsia in living kidney donors compared with nondonors. Further research is needed to better quantify the risk of adverse maternal, fetal/infant, and neonatal outcomes attributable to living kidney donation.

Objective

To determine the risk of hypertensive disorders of pregnancy, including gestational hypertension, pre-eclampsia, and eclampsia, and other maternal and fetal/infant outcomes in living kidney donors compared with a matched group of nondonors of similar baseline health.

Design and Setting

Protocol for a population-based, matched cohort study using Canadian administrative health care databases. The protocol will be run separately in 3 provinces, Ontario, Alberta, and British Columbia, and results will be combined statistically using meta-analysis.

Participants

The cohort will include women aged 18 to 48 years who donated a kidney between July 1992 and March 2022 and had at least one postdonation singleton pregnancy of ≥20 weeks gestation between January 1993 and February 2023. We expect to include at least 150 living kidney donors with over 200 postdonation pregnancies from Ontario and a similar number of donors and pregnancies across Alberta and British Columbia combined. Nondonors will include women from the general population with at least one pregnancy of ≥20 weeks gestation between January 1993 and February 2023. Nondonors will be randomly assigned cohort entry dates based on the distribution of nephrectomy dates in donors. The sample of nondonors will be restricted to those aged 18 to 48 years on their cohort entry dates with delivery dates at least 6 months after their assigned entry dates. A concern with donor and nondonor comparisons is that donors are healthier than the general population. To reduce this concern, we will also apply 30+ exclusion criteria to further restrict the nondonor group so that they have similar health measures at cohort entry as the donors. Donor and nondonor pregnancies will then be matched (1:4) on 5 potential confounders: delivery date, maternal age at delivery date, time between cohort entry and delivery date, neighborhood income quintile, and parity at delivery date.

Measurements

The primary outcome will be a composite of maternal gestational hypertension, preeclampsia, or eclampsia. Secondary maternal outcomes will include components of the primary outcome, early pre-eclampsia, severe maternal morbidity, cesarean section, postpartum hemorrhage, and gestational diabetes. Fetal/infant/neonatal outcomes will include premature birth/low birth weight, small for gestational age, neonatal intensive care unit admission, stillbirth, and neonatal death.

Methods

The primary unit of analysis will be the pregnancy. We will compute the risk ratio of the primary composite outcome in donors versus nondonors using a log-binomial mixed regression model with random effects to account for the correlation within women with multiple pregnancies and within matched sets of donors and nondonors. We will perform the statistical analyses within each province and then combine aggregated results using meta-analytic techniques to produce overall estimates of the study outcomes.

Limitations

Due to regulations that prevent individual-level records from being sent to other provinces, we cannot pool individual-level data from all 3 provinces.

Conclusion

Compared to prior studies, this study will better estimate the donation-attributable risk of adverse maternal, fetal/infant, and neonatal outcomes. Transplant centers can use the results to counsel female living donor candidates of childbearing age and to inform recommended practices for the follow-up and care of living kidney donors who become pregnant.

Performance of the New CKD-EPI Creatinine-and Cystatin C-based Glomerular Filtration Rate Estimation Equation in Living Kidney Donor Candidate

Background

Accurate preoperative evaluation of renal function in living kidney donor candidates (LKDCs) is crucial to prevent kidney failure after nephrectomy. We examined the performance of various estimated glomerular filtration rate (eGFR) equations, including the new chronic kidney disease epidemiology collaboration (CKD-EPI) equation in LKDCs.

Methods

We analyzed 752 LKDCs who were assessed for measured GFR by inulin clearance as part of routine pretransplant examination from 2006 to 2020. CKD-EPI2012 from cystatin C (CKD-EPI12cys), CKD-EPI2021 from creatinine (CKD-EPI21cr), CKD-EPI21cr-cys, Japanese modified (JPN) eGFRcr, and JPN eGFRcys were compared in determining the suitability for LKDCs.

Results

CKD-EPI12cys had the lowest absolute and relative biases, with higher P30 and P10, followed by JPN eGFRcys, CKD-EPI21cr, and CKD-EPI21cr-cys. The root mean square error was least for CKD-EPI12cys, then JPN eGFRcys, CKD-EPI21cr-cys, CKD-EPI21cr, and JPN eGFRcr. CKD-EPI21cr, CKD-EPI12cys, and CKD-EPI21cr-cys estimated GFR higher, whereas JPN eGFRcr estimated GFR lower. At the threshold of 90 mL/min/1.73 m2, CKD-EPI21cr had the highest percentage of misclassification at 37.37%, whereas JPN eGFRcr had the lowest percentage of misclassification at 6.91%. Using the age-adapted approach, JPN eGFRcr had the lowest percentage of misclassification into overestimation at 7.31%. All eGFR had >5.0%, and CKD-EPI21cr had the highest percentage of misclassification at 21.94%. Conversely, CKD-EPI21cr-cys had the lowest percentage of misclassification into underestimation at 3.19%, both at the threshold of 90 mL/min/1.73 m2 and the age-adapted approach. JPN eGFRcr had the highest percentage at 33.38% and 40.69%, respectively.

Conclusions

In evaluating the renal function of Japanese LKDCs, the new CKD-EPI equation had a lower rate of underestimation but a relatively high rate of overestimation. New GFR estimation formulas are needed to be tailored to each ethnic group to enhance the accuracy and reliability of donor selection processes.

Relmapirazin, a new exogenous filtration marker, and more widespread use of measured GFR

Plasma or urinary clearance of exogenous filtration markers is required for assessment of measured glomerular filtration rate. Although multiple methods are available, none is widely used because of their complexity, each has measurement error, and standardization is limited. Recently, a study validated the plasma clearance of a new exogenous filtration marker, relmapirazin, which can be detected by its transdermal fluorescence, potentially simplifying the procedure and increasing access to measured glomerular filtration rate.

Thirty-Year Trends in Perioperative Mortality Risk for Living Kidney Donors

This study uses a national registry study to characterize temporal trends in perioperative mortality in donors and risk factors associated with this event.

WT1-related disorders: more than Denys-Drash syndrome

Historically, specific mutations in WT1 gene have been associated with distinct syndromes based on phenotypic characteristics, including Denys-Drash syndrome (DDS), Frasier syndrome (FS), Meacham syndrome, and WAGR syndrome. DDS is classically defined by the triad of steroid-resistant nephrotic syndrome (SRNS) onset in the first year of life, disorders of sex development (DSD), and a predisposition to Wilms tumor (WT). Currently, a paradigm shift acknowledges a diverse spectrum of presentations beyond traditional syndromic definitions. Consequently, the concept of WT1-related disorders becomes more precise. A genotype-phenotype correlation has been established, emphasizing that the location and type of WT1 mutations significantly influence the clinical presentation, the condition severity, and the chronology of patient manifestations. Individuals presenting with persistent proteinuria, with or without nephrotic syndrome, and varying degrees of kidney dysfunction accompanied by genital malformations should prompt suspicion of WT1 mutations. Recent genetic advances enable a more accurate estimation of malignancy risk in these patients, facilitating a conservative nephron-sparing surgery (NSS) approach in select cases, with a focus on preserving residual kidney function and delaying nephrectomies. Other key management strategies include kidney transplantation and addressing DSD and gonadoblastoma. In summary, recent genetic insights underscore the imperative to implement individualized, integrated, and multidisciplinary management strategies for WT1-related disorders. This approach is pivotal in optimizing patient outcomes and addressing the complexities associated with these diverse clinical manifestations.

Longitudinal Trajectories of Estimated Glomerular Filtration Rate in a European Population of Living Kidney Donors

A living donor (LD) kidney transplant is the best treatment for kidney failure, but LDs safety is paramount. We sought to evaluate our LDs cohort's longitudinal changes in estimated glomerular filtration rate (eGFR). We retrospectively studied 320 LDs submitted to nephrectomy between 1998 and 2020. The primary outcome was the eGFR change until 15 years (y) post-donation. Subgroup analysis considered distinct donor characteristics and kidney function reduction rate (%KFRR) post-donation [-(eGFR6 months(M)-eGFRpre-donation)/eGFRpre-donation*100]. Donors had a mean age of 47.3 ± 10.5 years, 71% female. Overall, LDs presented an average eGFR change 6 M onward of +0.35 mL/min/1.73 m2/year. The period with the highest increase was 6 M-2 Y, with a mean eGFR change of +0.85L/min/1.73 m2/year. Recovery plateaued at 10 years. Normal weight donors presented significantly better recovery of eGFR +0.59 mL/min/1.73 m2/year, compared to obese donors -0.18L/min/1.73 m2/year (p = 0.020). Noteworthy, these results only hold for the first 5 years. The subgroup with a lower KFRR (<26.2%) had a significantly higher decrease in eGFR overall of -0.21 mL/min/1.73 m2/year compared to the groups with higher KFRR (p < 0.001). These differences only hold for 6 M-2 Y. Moreover, an eGFR<50 mL/min/1.73 m2 was a rare event, with ≤5% prevalence in the 2-15 Y span, correlating with eGFR pre-donation. Our data show that eGFR recovery is significant and may last until 10 years post-donation. However, some subgroups presented more ominous kidney function trajectories.

Donor Perceptions and Preferences of Telemedicine and In-Person Visits for Living Kidney Donor Evaluation

Introduction

Living kidney donor evaluation is a lengthy and complex process requiring in-person visits. Access to transplant centers, travel costs, lost wages, and dependent care arrangements are barriers to willing donors initiating evaluation. Telemedicine can help streamline and epedite the evaluation process. We aimed to deeply understand donor experiences and preferences using hybrid telemedicine video/in-person visits to ease access to donor evaluation or counseling.

Methods

We conducted in-depth, semistructured interviews with donors or donor candidates who completed their evaluation through telemedicine/in-person, or in-person only visits at a tertiary transplant center between November 27, 2019 and March 1, 2021. Enrollment continued until data saturation was reached (interviews with 20 participants) when no new information emerged from additional interviews. Transcripts were analyzed using inductive thematic analysis.

Results

Eight themes were identified as follows: (i) reducing financial and logistical burdens (minimizing travel time and travel-related expenses), (ii) enhancing flexibility with scheduling (less time off work and child or family caregiver arrangements), (iii) importance of a walkthrough and establishing shared understanding, (iv) supporting information with technology and visual aids, (v) key role of the coordinator, (vi) preferred visit by provider role (meeting donor surgeon in-person to create rapport and engaging primary care provider in donor evaluation/follow-up), (vii) comparing modality differences in human connection, and (viii) opportunity for family and support network engagement (allowing loved ones to be involved in telemedicine visits irrespective of geographic locations and pandemic restrictions).

Conclusion

Telemedicine/in-person hybrid model can make donor evaluation more accessible and convenient. Our findings help inform about determinants that influence the adoption of telemedicine to initiate donor evaluation to motivate willing donors. In addition, our results call for policy and legislation that support telemedicine services for living donor kidney transplantation across states.

Integrating Machine Learning into Statistical Methods in Disease Risk Prediction Modeling: A Systematic Review

Background: Disease prediction models often use statistical methods or machine learning, both with their own corresponding application scenarios, raising the risk of errors when used alone. Integrating machine learning into statistical methods may yield robust prediction models. This systematic review aims to comprehensively assess current development of global disease prediction integration models. Methods: PubMed, EMbase, Web of Science, CNKI, VIP, WanFang, and SinoMed databases were searched to collect studies on prediction models integrating machine learning into statistical methods from database inception to 2023 May 1. Information including basic characteristics of studies, integrating approaches, application scenarios, modeling details, and model performance was extracted. Results: A total of 20 eligible studies in English and 1 in Chinese were included. Five studies concentrated on diagnostic models, while 16 studies concentrated on predicting disease occurrence or prognosis. Integrating strategies of classification models included majority voting, weighted voting, stacking, and model selection (when statistical methods and machine learning disagreed). Regression models adopted strategies including simple statistics, weighted statistics, and stacking. AUROC of integration models surpassed 0.75 and performed better than statistical methods and machine learning in most studies. Stacking was used for situations with >100 predictors and needed relatively larger amount of training data. Conclusion: Research on integrating machine learning into statistical methods in prediction models remains limited, but some studies have exhibited great potential that integration models outperform single models. This study provides insights for the selection of integration methods for different scenarios. Future research could emphasize on the improvement and validation of integrating strategies.

Non-contrast preoperative MRI for determining renal perfusion and visualizing renal arteries in potential living kidney donors at 1.5 Tesla

Background

The aim of this work was to create and evaluate a preoperative non-contrast-enhanced (CE) magnetic resonance imaging (MRI)/angiography (MRA) protocol to assess renal function and visualize renal arteries and any abnormalities in potential living kidney donors.

Methods

In total, 28 subjects were examined using scintigraphy to determine renal function. In addition, 3D-pseudocontinuous arterial spin labeling (pCASL), a 2D-non-CE electrocardiogram-triggered radial quiescent interval slice-selective (QISS-MRA), and 4D-CE time-resolved angiography with interleaved stochastic trajectories (CE-MRA) were performed to assess renal perfusion, visualize renal arteries and detect any abnormalities. Two glomerular filtration rates [described by Gates (GFRG) and according to the Chronic Kidney Disease Epidemiology Collaboration formula (GFRCKD-EPI)]. The renal volumes were determined using both MRA techniques.

Results

The mean value of regional renal blood flow (rRBF) on the right side was significantly higher than that on the left. The agreements between QISS-MRA and CE-MRA concerning the assessment of absence or presence of an aberrant artery and renal arterial stenosis were perfect. The mean renal volumes measured in the right kidney with QISS-MRA were lower than the corresponding values of CE-MRA. In contrast, the mean renal volumes measured in the left kidney with both MRA techniques were similar. The correlation between the GFRG and rRBF was compared in the same manner as that between GFRCKD-EPI and rRBF.

Conclusion

The combination of pCASL and QISS-MRA constitute a reliable preoperative protocol with a total measurement time of <10 min without the potential side effects of gadolinium-based contrast agents or radiation exposure.

Robotic versus laparoscopic versus open nephrectomy for live kidney donors

BACKGROUND

Waiting lists for kidney transplantation continue to grow. Live kidney donation significantly reduces waiting times and improves long-term outcomes for recipients. Major disincentives to potential kidney donors are the pain and morbidity associated with surgery. This is an update of a review published in 2011.

OBJECTIVES

To assess the benefits and harms of open donor nephrectomy (ODN), laparoscopic donor nephrectomy (LDN), hand-assisted LDN (HALDN) and robotic donor nephrectomy (RDN) as appropriate surgical techniques for live kidney donors.

SEARCH METHODS

We contacted the Information Specialist and searched the Cochrane Kidney and Transplant Register of Studies up to 31 March 2024 using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Registry Platform (ICTRP) Search Portal, and ClinicalTrials.gov.

SELECTION CRITERIA

Randomised controlled trials (RCTs) comparing LDN with ODN, HALDN, or RDN were included.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened titles and abstracts for eligibility, assessed study quality, and extracted data. We contacted study authors for additional information where necessary. Summary estimates of effect were obtained using a random-effects model, and results were expressed as risk ratios (RR) and their 95% confidence intervals (CI) for dichotomous outcomes and mean difference (MD) or standardised mean difference (SMD) and 95% CI for continuous outcomes. Confidence in the evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach.

MAIN RESULTS

Thirteen studies randomising 1280 live kidney donors to ODN, LDN, HALDN, or RDN were included. All studies were assessed as having a low or unclear risk of bias for selection bias. Five studies had a high risk of bias for blinding. Seven studies randomised 815 live kidney donors to LDN or ODN. LDN was associated with reduced analgesia use (high certainty evidence) and shorter hospital stay, a longer procedure and longer warm ischaemia time (moderate certainty evidence). There were no overall differences in blood loss, perioperative complications, or need for operations (low or very low certainty evidence). Three studies randomised 270 live kidney donors to LDN or HALDN. There were no differences between HALDN and LDN for analgesia requirement, hospital stay (high certainty evidence), duration of procedure (moderate certainty evidence), blood loss, perioperative complications, or reoperations (low certainty evidence). The evidence for warm ischaemia time was very uncertain due to high heterogeneity. One study randomised 50 live kidney donors to retroperitoneal ODN or HALDN and reported less pain and analgesia requirements with ODN. It found decreased blood loss and duration of the procedure with HALDN. No differences were found in perioperative complications, reoperations, hospital stay, or primary warm ischaemia time. One study randomised 45 live kidney donors to LDN or RDN and reported a longer warm ischaemia time with RDN but no differences in analgesia requirement, duration of procedure, blood loss, perioperative complications, reoperations, or hospital stay. One study randomised 100 live kidney donors to two variations of LDN and reported no differences in hospital stay, duration of procedure, conversion rates, primary warm ischaemia times, or complications (not meta-analysed). The conversion rates to ODN were 6/587 (1.02%) in LDN, 1/160 (0.63%) in HALDN, and 0/15 in RDN. Graft outcomes were rarely or selectively reported across the studies. There were no differences between LDN and ODN for early graft loss, delayed graft function, acute rejection, ureteric complications, kidney function or one-year graft loss. In a meta-regression analysis between LDN and ODN, moderate certainty evidence on procedure duration changed significantly in favour of LDN over time (yearly reduction = 7.12 min, 95% CI 2.56 to 11.67; P = 0.0022). Differences in very low certainty evidence on perioperative complications also changed significantly in favour of LDN over time (yearly change in LnRR = 0.107, 95% CI 0.022 to 0.192; P = 0.014). Various different combinations of techniques were used in each study, resulting in heterogeneity among the results.

AUTHORS' CONCLUSIONS

LDN is associated with less pain compared to ODN and has comparable pain to HALDN and RDN. HALDN is comparable to LDN in all outcomes except warm ischaemia time, which may be associated with a reduction. One study reported kidneys obtained during RDN had greater warm ischaemia times. Complications and occurrences of perioperative events needing further intervention were equivalent between all methods.

Clinical Impacts of Implementing the 2021 Race-Free Chronic Kidney Disease Epidemiology Collaboration Estimated Glomerular Filtration Rate

BACKGROUND

Estimated glomerular filtration rate (eGFR) has become incorporated into multiple clinical management situations. Historically, equations included a Black race coefficient, which lacked biological plausibility and created potential to exacerbate health disparities. A new equation created in 2021 changed the weighting of age, sex, and creatinine by modeling against a diverse cohort and removing the Black race coefficient.

CONTENT

A variety of clinical outcomes including kidney disease risk stratification, medication dosing, patient eligibility for clinical trials, and kidney donation are impacted by implementation of the new equation. Nearly 2 years after its initial publication, many studies have reported on observed analytical performance of the 2021 eGFR determined as diagnostic concordance and percentage of estimates within 30% of measured GFR. Additionally, the potential clinical impacts following adoption of the new eGFR among different patient populations has also been reported. Here we review these studies with a focus on assessing the data associated with the transition from 2009 to 2021 Chronic Kidney Disease Epidemiology Collaboration equations.

SUMMARY

The reported interindividual variation in eGFR performance is significantly larger than any potential benefit derived from race coefficients. Both the 2021 eGFR and the 2009 eGFR analytical performance fall short of the validation cohort performance in most cohorts. However, the 2021 analytical is similar or better than the 2009 eGFR in most cohorts. Implementing the 2021 eGFR will remove a systematic overestimation of kidney function among Black patients.

Bariatric surgery in prospective obese living kidney donors: scoping review and management decision algorithm

INTRODUCTION

Global chronic kidney disease is now epidemic, with substantial health and economic consequences. While scientific support for living donor renal transplants (LDRT) is strong, donor shortages necessitate consideration of expanded criteria, including obese individuals. Bariatric surgery (BS) may mitigate obesity-related risks, but research on living donor candidates is scarce. Our scoping review aims to compile evidence, identify gaps, and formulate an algorithm to guide healthcare professionals in evaluating BS for obese living donors.

EVIDENCE ACQUISITION

We did a systematic search of studies on living kidney donors and obesity. We searched the MEDLINE Ovid, Embase Ovid, CENTRAL and Web of Science databases for studies from database inception to March 30, 2023. All English-language articles available in full text have been considered. Excluded are commentaries, editorials, letters, and abstracts.

EVIDENCE SYNTHESIS

Obesity in LDRT raises long-term ESRD risk. Current high BMI donor admission raises ethical and clinical concerns. Encouraging timely weight loss can make obese candidates suitable donors, reducing risks. Sleeve gastrectomy is the most reported and preferable approach, since it minimizes hyperoxaluria risk. Re-evaluation for donation is possible 6-12 months post-BS, with BMI<35 for three months. Cost-benefit analysis favors BS over nephrectomy in obese donors (cost-benefit ratio: 3.64) when graft survival is equal.

CONCLUSIONS

BS shows promise with short-term effectiveness and potential long-term outcomes. However, it should not be perceived as a means to expand the donor pool but rather as a personalized approach to address obesity and improve individuals' health.

Prediction models for postoperative renal function after living donor nephrectomy: a systematic review

INTRODUCTION

Living-donor nephrectomy (LDN) is the most valuable source of organs for kidney transplantation worldwide. The current preoperative evaluation of a potential living donor candidate does not take into account formal estimation of postoperative renal function decline after surgery using validated prediction models. The aim of this study was to summarize the available models to predict the mid- to long-term renal function following LDN, aiming to support both clinicians and patients during the decision-making process.

EVIDENCE ACQUISITION

A systematic review of the English-language literature was conducted following the principles highlighted by the European Association of Urology (EAU) guidelines and following the PRISMA 2020 recommendations. The protocol was registered in PROSPERO on December 10, 2022 (registration ID: CRD42022380198). In the qualitative analysis we selected the models including only preoperative variables.

EVIDENCE SYNTHESIS

After screening and eligibility assessment, six models from six studies met the inclusion criteria. All of them relied on retrospective patient cohorts. According to PROBAST, all studies were evaluated as high risk of bias. The models included different combinations of variables (ranging between two to four), including donor-/kidney-related factors, and preoperative laboratory tests. Donor age was the variable more often included in the models (83%), followed by history of hypertension (17%), Body Mass Index (33%), renal volume adjusted by body weight (33%) and body surface area (33%). There was significant heterogeneity in the model building strategy, the main outcome measures and the model's performance metrics. Three models were externally validated.

CONCLUSIONS

Few models using preoperative variables have been developed and externally validated to predict renal function after LDN. As such, the evidence is premature to recommend their use in routine clinical practice. Future research should be focused on the development and validation of user-friendly, robust prediction models, relying on granular large multicenter datasets, to support clinicians and patients during the decision-making process.

MSCTA imaging analysis of autologous arteriovenous fistula dysfunction in maintenance hemodialysis patients

OBJECTIVE

To observe the multi-slice spiral CT angiography (MSCTA) imaging features of arteriovenous fistula dysfunction in patients undergoing maintenance hemodialysis and analyze the significance of the imaging examination.

METHODS

Altogether 90 patients with end-stage renal disease treated by maintenance hemodialysis in General Hospital of China Resources & Wisco from June 2020 to February 2023 were divided into a normal function group (n=68) and a dysfunction group (n=22) according to the function of autogenous arteriovenous fistula. The clinical data of the two groups were recorded. The MSCTA was performed in each patient, and the manifestations of arteriovenous fistula dysfunction were analyzed. Additionally, the vascular access stenosis, vascular access lumen stenosis, arteriovenous diameter, blood flow, and hemodynamic indices were tested, and the value of MSCTA in predicting arteriovenous fistula function was analyzed by Logistic regression.

RESULTS

The degree of vascular access stenosis and vascular access lumen stenosis in the normal group were less than those in the dysfunctional group (P<0.05). The arteriovenous diameter, blood flow, blood flow velocity at anastomotic vein end, dialysis adequacy (spKt/V), and von Willebrand factor (vWF) function in the normal group were larger than those in the dysfunction group, and the radial artery shear force was lower than in the dysfunction group, with statistical significance (P<0.05). Among the arteriovenous fistula dysfunction, there were 3 patients with anastomotic + outflow vein stenosis, 4 patients with outflow vein stenosis, 9 patients with inflow artery + anastomosis + outflow vein stenosis, and 6 patients with superior vena cava stenosis. Logistic regression analysis showed that slow blood flow velocity at the venous end of anastomosis and high shear force of radial artery were influencing factors of arteriovenous fistula dysfunction, and the area under ROC curve of blood flow velocity at the venous end of anastomosis plus shear force of radial artery was 0.93, with a sensitivity of 0.87 and a specificity of 0.85.

CONCLUSION

MSCTA can be used to evaluate the dysfunction of autologous arteriovenous fistula in patients undergoing maintenance hemodialysis, and provide important reference information for the formulation of the next best clinical treatment plan.

Clinical performance of the iPREDICTLIVING tool for the prediction of the post-transplant recipient and living donor outcomes in a European cohort

A living donor kidney transplant (LDKT) is the best treatment for ESRD. A prediction tool based on clinical and demographic data available pre-KT was developed in a Norwegian cohort with three different models to predict graft loss, recipient death, and donor candidate's risk of death, the iPREDICTLIVING tool. No external validations are yet available. We sought to evaluate its predictive performance in our cohort of 352 pairs LKDT submitted to KT from 1998 to 2019. The model for censored graft failure (CGF) showed the worse discriminative performance with Harrell's C of .665 and a time-dependent AUC of .566, with a calibration slope of .998. For recipient death, at 10 years, the model had a Harrell's C of .776, a time-dependent AUC of .773, and a calibration slope of 1.003. The models for donor death were reasonably discriminative, although with a poor calibration, particularly for 20 years of death, with a Harrell's C of .712 and AUC of .694 with a calibration slope of .955. These models have moderate discriminative and calibration performance in our population. The tool was validated in this Northern Portuguese cohort, Caucasian, with a low incidence of diabetes and other comorbidities. It can improve the informed decision-making process at the living donor consultation joining clinical and other relevant information.

Improving value delivery in living donor kidney transplant through process improvement

INTRODUCTION

Living donor kidney evaluation has substantial time variations with significant intercenter variation. One-day donor evaluation has shown to be clinically efficient and improve transplant rates. However, patients' perception of 1-day evaluation is unknown. We hypothesized that 1 day LKD evaluation will improve patient satisfaction and improve living donation rates.

METHODS

All interested LD candidates from April 2018 to May 2020 were enrolled in the study. Non-directed donors, donors greater than 60 years old, and recipients with more than three donors underwent multi-day evaluation (control group) while the rest underwent 1-day evaluation (intervention group). An anonymous survey was filled by both groups to assess their perceptions on different areas including time, communication, experience, information provided, and their preferences on living donor evaluation.

RESULTS

Donor candidates in the 1-day evaluation group selected that the time from the questionnaire to clinic evaluation took "under 1 month" or "less than 3 months" (62.5% vs. 15.8%, p = .002), with "excellent" for both scheduling process (65% vs. 31.6%, p = .03) and communication (82.5% vs. 57.9%, p = .09) when compared to candidates in the multiple-days evaluation group. One-day candidates felt "very satisfied" with the overall experience (95% vs. 68.4%, p = .02) and felt "extremely well" with the information provided regarding the living donor process (87.5% vs. 47.4%, p = .003) when compared to multiple-day evaluation group. Regardless of the group, 53 (89.8%) patients preferred 1-day evaluation.

CONCLUSION

We demonstrate 1-day living donor evaluation is efficient, patient preferred, and adds value through improved communication, and better overall patient satisfaction.

Performance of estimated glomerular filtration rate equations in Black living kidney donor candidates

INTRODUCTION

New estimated glomerular filtration rate (eGFR) equations using serum creatinine and/or cystatin C have been derived to eliminate adjustment by perceived Black ancestry. We sought to analyze the performance of newer eGFR equations among Black living kidney donor candidates.

METHODS

Black candidates (n = 64) who had measured iothalamate GFR between January 2015 and October 2021 were included, and eGFR was calculated using race adjusted (eGFRcr2009 and eGFRcr-cys2012) and race unadjusted (eGFRcys2012, eGFRcr2021, and eGFRcr-cys2021) CKD-EPI equations. Bias and accuracy were calculated.

RESULTS

The eGFRcr2021 equation had a negative bias of 9 mL/min/1.73 m2 , while other equations showed a modest positive bias. Accuracy within 10% and 30% was greatest using the eGFRcr-cys2021 equation. With the eGFRcr2021 equation, 9.4% of donors with an mGFR > 80 mL/min/1.73 m2 were misclassified as having an eGFR < 80 mL/min/1.73 m2 . eGFR was also compared among 18 kidney donors at 6-24 months post-donation. Post-donation, the percentage of donors with an eGFR < 60 mL/min/1.73 m2 was 44% using the eGFRcr2021 equation compared to 11% using the eGFRcr-cys2021 equation.

CONCLUSION

The CKD-EPICr2021 equation appears to underestimate true GFR in Black living donor candidates. Alternatively, compared to CKD-EPICr2021, the CKD-EPICr-CysC2021 equation appears to perform with less bias and improved accuracy.

No difference in follow-up estimated glomerular filtration rate between hypertensive and matched nonhypertensive kidney donors

BACKGROUND

According to current guidelines, kidney donor candidates with controlled hypertension using 1 or 2 antihypertensive drugs may be considered as donor. However, this recommendation is based on the study that antihypertensive drug was initiated in mainly "after donor registration" and this may be white-coat hypertension because of donation-related anxiety. We compared the follow-up eGFR between kidney donors with preexisting hypertension and matched nonhypertensive donors.

METHODS

This single-center retrospective study classified 97 living hypertensive donors previously receiving antihypertensive drugs into two groups: 1 drug group (61 donors) and 2 drugs group (36 donors). We compared the follow-up eGFR between each donor previously receiving antihypertensive drugs and three matched nonhypertensive donors in terms of age, sex, and follow-up duration.

RESULTS

At a mean (range) of 51 months (12-214) in the 1 drug group, and 54 months (12-175) in the 2 drugs group after donation, there was no significant difference in follow-up eGFR between hypertensive donors previously receiving antihypertensive drugs and matched controls in each group and in total donors. There was no difference in the incidence of the patients with follow-up eGFR<45mL/min/m2 in each group and their matched controls. Multiple linear regression analysis showed that baseline eGFR was the only independent predictor for the final follow-up eGFR in the total donors.

CONCLUSION

Our results support the current guidelines that donor candidates with controlled hypertension using 1 or 2 antihypertensive drugs may be considered as donors, and may increase the strength of this recommendation.

Glomerular Filtration Rate Measured Based on Iomeprol Clearance Assessed at CT Urography in Living Kidney Donor Candidates

Background Estimating glomerular filtration rate (GFR) from serum creatinine can be inaccurate, and current procedures for measuring GFR are time-consuming and cumbersome. Purpose To develop a method for measuring GFR based on iomeprol clearance assessed at CT urography in kidney donor candidates and compare this with iohexol clearance (reference standard for measuring GFR). Materials and Methods This cross-sectional retrospective study included data from kidney donor candidates who underwent both iohexol clearance and CT urography between July 2016 and October 2022. CT-measured GFR was calculated as the iomeprol excretion rate in the urinary system between arterial and excretory phases (Hounsfield units times milliliters per minute) divided by a surrogate for serum iomeprol concentration in the aorta at the midpoint (in Hounsfield units). Performance of CT-measured GFR was assessed with use of mean bias (mean difference between CT-measured GFR and iohexol clearance), precision (the distance between quartile 1 and quartile 3 of the bias [quartile 3 minus quartile 1], with a small value indicating high precision), and accuracy (percentage of CT-measured GFR values falling within 10%, 20%, and 30% of iohexol clearance values). Intraobserver agreement was assessed for 30 randomly selected individuals with the Lin concordance correlation coefficient. Results A total of 75 kidney donor candidates were included (mean age, 51 years ± 13 [SD]; 45 female). The CT-measured GFR was unbiased (1.1 mL/min/1.73 m2 [95% CI: -1.9, 4.1]) and highly precise (16.2 mL/min/1.73 m2 [quartiles 1 to 3, -6.6 to 9.6]). The accuracy of CT-measured GFR within 10%, 20%, and 30% was 61.3% (95% CI: 50.3, 72.4), 88.0% (95% CI: 80.7, 95.4), and 100%, respectively. Concordance between CT-based GFR measurements taken 2 months apart was almost perfect (correlation coefficient, 0.99 [95% CI: 0.98, 0.99]). Conclusion In living kidney donors, GFR measured based on iomeprol clearance assessed at CT urography showed good agreement with GFR measured based on iohexol clearance. © RSNA, 2023 Supplemental material is available for this article. See also the editorial by Davenport in this issue.

Expanding the donor pool: Kidney transplantation from serum HBV DNA or HBeAg-positive donors to HBsAg-negative recipients

BACKGROUND & AIMS

HBsAg-positive (HBsAg[+]) donors are rarely accepted for kidney transplantation (KT), especially when the donor is also HBV DNA-positive (HBV DNA[+]) or HBeAg-positive (HBeAg[+]) serologically. This study aimed to report kidney transplant outcomes from HBsAg(+) donors to HBsAg(-) recipients.

METHODS

Consecutive cases were retrospectively identified from 1 July 2017 to 31 December 2020. KTs from HBsAg(-)/HBcAb-positive (HBcAb[+]) donors to HBcAb(-) recipients were selected as the control group. The primary outcomes were de novo HBV infection (DNH), graft and patient survival.

RESULTS

We identified 105 HBsAg(-) recipients who received HBsAg(+) kidneys and 516 HBcAb(-) recipients who received HBcAb(+) kidneys. A higher DNH rate was observed after receiving HBsAg(+) kidneys than after receiving HBcAb(+) kidneys after a median follow-up of 23.0 months (4/105[3.8%] vs. 2/516[0.4%], p = .009). All four infected recipients receiving HBsAg(+) kidneys had HBsAg clearance after treatment. Graft and patient survival were comparable between the groups (p = .630, p = .910). The DNH rates were 0/22(0%), 3/70(4.3%) and 1/13(7.7%) after receiving HBsAg(+), HBV DNA(+) and HBeAg(+) kidneys, respectively (p = .455). The DNH rate was lower if the donor had received antiviral treatment (4/42[9.5%] vs. 0/63[0%], p = .023). HBsAb(-) recipients had a higher DNH incidence than HBsAb(+) recipients (3/25[12.0%] vs. 1/80[1.3%], p = .041).

CONCLUSIONS

The use of HBsAg(+) donors contributed to comparable graft and patient survival, but HBV DNA(+) or HBeAg(+) donors and HBsAb(-) recipients maybe associated with a higher risk of HBV infection. These findings help expand the donor pool and emphasize the role of donor antiviral treatment and recipient HBV immunity in establishing optimal prophylactic regimens.

Living Donors' Age Modifies the Impact of Pre-Donation Estimated Glomerular Filtration Rate on Graft Survival

BACKGROUND

The global scarcity of organs for kidney transplants (KTs) has led to the increased acceptance of living donors (LDs) with minor abnormalities to increase the donor pool.. We sought to evaluate the effects of some of these LDs' clinical characteristics (older age, borderline renal function, hypertension, dyslipidemia, smoking, and obesity) on graft outcomes.

METHODS

We studied 352 recipients of LDKTs (1998-2020). Firstly, considering the recipients and KT variables, we identified relevant predictors of overall and censored graft failure (GF). Then, adjusting for these predictors, we explored LD variables as predictors of overall and censored GF in a multivariable Cox model.

RESULTS

The recipients from LD with higher eGFR (≥90 mL/min/1.73 m2) had significantly better overall and censored graft survival GS) at 15 y after KT (respectively, 67 and 75% vs. 46 and 46%, p < 0.001). Importantly, none of the remaining LD factors which were evaluated (hypertension, dyslipidemia, smoking, proteinuria, and obesity) were independent predictors of GF. In recipients from LDs < 50 y, having an eGFR < 90 was an independent predictor of overall GF [adjusted HR (95%CI) of 2.578 (1.120-5.795)] and censored GF [adjusted HR (95%CI) of 3.216 (1.300-7.959)], compared to recipients from LDs with eGFR ≥ 90. Contrarily, when donors were older, no difference in the risk of GF was observed between eGFR categories.

CONCLUSION

In our cohort, lower pre-donation eGFR had an impact on GS only in younger LDs. An age-adjusted eGFR cutoff may be pursued for improved donor admissibility.

Predictive Value of Camera-based Donor Glomerular Filtration Rate Estimation on the Immediate Renal Allograft Outcome Following Live-related Renal Transplant: A Single-center Retrospective Study

Purpose of the Study

The purpose of this study was to assess the association of measured glomerular filtration rate (mGFR) using camera-based method with early transplant outcomes.

Methodology

Diethylenetriamine pentaacetate renograms of all voluntary kidney donors between January 2016 and December 2022 at Kasturba Hospital, Manipal, India, were retrieved for the study. Recipients' posttransplant biochemical parameters were collected and compared against donors with scaled mGFR >80 ml/min/1.73 m2 (Group 1) and with mGFR between 60 and 80 ml/min/1.73 m2 (Group 2). Donor-recipient pair age, anthropometric parameters, and their differences were also assessed against the immediate transplant outcome. Posttransplant immediate graft function was assessed by posttransplant nadir serum creatinine, day to achieve nadir serum creatinine, the incidence of slow graft or delayed graft function, and serum creatinine at 1-month posttransplantation. Recipients with serum creatinine of >2.5 mg/dl on posttransplant day 7 were taken as slow graft function.

Results

A total of 161 donor-recipient pairs were analyzed in the study. In recipients who showed persistently high serum creatinine posttransplant, older donor age(p < 0.001), higher difference in body mass index among the donor-recipient pair (p= 0.03), and mGFR <80ml/min (p < 0.001) were significantly associated. Slow graft function was significantly more in Group II recipients, with donors having mGFR <80ml/min as compared to Group I with mGFR >80 ml/min (37.3% vs. 10.6%) (P < 0.001).

Conclusions

Camera-based mGFR using Gates' formula is a reliable tool to predict inferior graft outcomes in the immediate posttransplant period. Kidneys from donors with mGFR of 60-80 mL/min/1.73 m2 are likely to experience slow graft function in the immediate posttransplant period.

Accuracy-Based Glomerular Filtration Rate Assessment by Plasma Iohexol Clearance in Kidney Transplant Donors

BACKGROUND

An accurate measurement of the glomerular filtration rate (GFR) is essential for detecting renal insufficiency in living kidney donors. Iohexol is a "near-ideal" exogenous filtration marker for GFR measurements that has attracted increasing interest in clinical practice because it is non-toxic, non-radioactive, readily available, and easy to measure. In this study, we aimed to set up a laboratory test to conveniently assess the plasma clearance of iohexol in living kidney donors.

METHODS

A workflow was established in the institution's infusion clinic to administer iohexol and to collect three timed blood samples from renal transplant donors. Iohexol was thereafter measured by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The serum proteins were precipitated and the supernatant containing iohexol was diluted prior to the LC-MS/MS analysis. The LC-MS/MS method was developed on a Thermo Vanquish UHPLC coupled with a TSQ Endura triple quadruple mass spectrometer with a total run time of 2.5 min. The analytical performance of the method was assessed.

RESULTS

The LC-MS/MS method demonstrated a good analytical performance. To calculate the iohexol clearance rate and the GFR, automated data integration and a result calculation were accomplished by using a custom Python script. Automated result reporting was achieved using a laboratory informatics system (LIS) vendor's direct media interface.

CONCLUSIONS

We developed and implemented a laboratory test to assess the plasma clearance of iohexol. A workflow was established in the hospital to reliably measure the GFR in living kidney donors, with a potential to be further expanded into other areas where an accurate GFR measurement is needed.

External Validation of Toulouse-Rangueil eGFR12 Prediction Model After Living Donor Nephrectomy

Decreased postdonation eGFR is associated with a higher risk of ESRD after living kidney donation, even when accounting for predonation characteristics. The Toulouse-Rangueil model (TRM) estimates 12 month postdonation eGFR (eGFR12) to inform counseling of candidates for living donation. The TRM was validated in several single-center European cohorts but has not been validated in US donors. We assessed the TRM in living kidney donors in the US using SRTR data 1/2000-6/2021. We compared the 2021 CKD-EPI equation eGFR12 observed estimates to the TRM eGFR12 predictions. Median (IQR) bias was -3.4 (-9.3, 3.4) mL/min/1.73 m2. Bias was higher for males vs. females (bias [IQR] -4.4 [-9.9, 1.8] vs. -2.9 [-8.8, 4.1]) and younger (31-40) vs. older donors (>50) (bias -4.9 [-10.6, 3.0] vs. -2.1 [-7.5, 4.0]). Bias was also larger for Black vs. White donors (bias (-6.7 [-12.1, -0.3], p < 0.001) vs. (-3.4 [-9.1, 3.1], p < 0.001)). Overall correlation was 0.71. In a sensitivity analysis using the 2009 CKD-EPI equation, results were generally consistent with exception to a higher overall bias (bias -4.2 [-9.8, 2.4]). The TRM overestimates postdonation renal function among US donors. Overestimation was greatest for those at higher risk for postdonation ESRD including male, Black, and younger donors. A new equation is needed to estimate postdonation renal function.

Pregnancy in Living Kidney Donors: An Evidence-Based Review

Purpose of review

To review the current studies and guidelines on the risk of adverse pregnancy outcomes in female kidney donors.

Recent findings

Living kidney donors include a significant amount of young women of child-bearing age. Safety and possible risks of pregnancy after donation are a concern for female kidney donor candidates. Many current studies indicate a higher risk of preeclampsia in women after kidney donation. Considering the increasing number of living kidney donors, the maternal outcomes of living kidney donation is an active area of research.

Summary

Guidelines and consensus statements on the risk of pregnancy in living kidney donors recommend close monitoring of blood pressure, weight gain, and proteinuria during pregnancy. Current studies indicate an increased risk of hypertensive disorders of pregnancy in living kidney donors. Counseling and informing donor candidates about the possible risks is important.

Medical-ethical guidelines: Living donation of solid organs

No abstract available.

Genomic testing in patients with renal disease

Inherited kidney disease accounts for a significant proportion of chronic kidney disease and end-stage renal failure. There is increasing evidence that genetic testing for inherited kidney disease should be integrated into clinical care pathways at the earliest opportunity so that patients and their families can maximally benefit from carefully tailored care. Despite increased availability of genetic testing, the proportion of patients with renal disease undergoing genetic investigations remains low. This article introduces key concepts of genetic and genomic testing to the renal physician and addresses some common barriers to the wider integration of genetic testing in routine clinical practice to fully capitalise on recent advances in genomic medicine and improve patient outcomes.

Pregnancy After Kidney Donation: The Experience in a Cohort of Portuguese Living Donors

BACKGROUND

Living kidney donation (LKD) is a preferred treatment option for end-stage chronic kidney disease, but it can also pose potential risks for the donor, including hypertension and end-stage renal disease. Many donors are women of reproductive age who may have concerns about the effects of donation on future pregnancies. The aim of this study was to determine fetal and maternal outcomes in a cohort of pregnancies after LKD and to compare them with pregnancies before LKD.

METHODS

We conducted a retrospective analysis of living kidney donors of childbearing age (<46 years old) at the time of donation who got pregnant after LKD in our center between 1987 and 2020 (N = 13). Clinical data were collected, including demographic characteristics and maternal and fetal outcomes.

RESULTS

We observed 16 pregnancies after LKD and 12 pregnancies before LKD in the same group of patients. The rate of gestational hypertension was 12.5% in pregnancies after LKD and 8.3% before LKD (P = .999). There were 13 successful pregnancies after LKD with a mean gestational age of 38.6 ± 1.7 weeks. There were no episodes of acute kidney injury or other complications.

CONCLUSION

The present study suggests that LKD does not have a negative effect on maternal and fetal outcomes. However, caution should be taken due to the small sample size. We agree with the guidelines recommending close monitoring of post-donation pregnancies.

Comparison of GFR measurement with a two-blood sample technique using [99mTc]Tc-DTPA vs. creatinine-based equations in potential kidney donors

INTRODUCTION

Accurate determination of glomerular filtration rate (GFR) is crucial for selection of kidney donors. Nuclear medicine methods are considered accurate in measuring GFR but are not always easily available. The four-variable Modification of Diet in Renal Disease (MDRD4), Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI), and Full Age Spectrum (FAS) formulas are common equations for estimating GFR and are recommended for initial assessment of kidney donors. The aim of this study was to evaluate the performance of these GFR estimation equations compared with technetium-99m diethylenetriaminepentaacetic acid ([99mTc]Tc-DTPA) clearance.

METHODS

We compared GFR estimation by [99mTc]Tc-DTPA clearance using a two-blood sample method with estimation by MDRD4, CKD-EPI, and FAS creatinine-based equations in a population of healthy potential kidney donors.

RESULTS

A total of 195 potential kidney donors (68.2% female; mean age 49 years, range 21-75 years) were included in this study. Mean [99mTc]Tc-DTPA measured GFR (mGFR) was 101.5 ± 19.1 mL/min/1.73 m2. All three equations underestimated the GFR value measured by [99mTc]Tc-DTPA (MDRD4: -11.5 ± 18.8 mL/min/1.73 m2; CKD-EPI: -5.0 ± 17.4 mL/min/1.73 m2; FAS: -8.3 ± 17.4 mL/min/1.73 m2). Accuracy within 30% and 10% of the measured GFR value was highest for CKD-EPI.

CONCLUSION

The CKD-EPI equation showed better performance in estimating GFR in healthy potential kidney donors, proving to be a more accurate tool in the initial assessment of kidney donors. However, creatinine-based equations tended to underestimate kidney function. Therefore, GFR should be confirmed by another method in potential kidney donors.

Comparison of Three Glomerular Filtration Rate Estimating Equations with 24-Hour Urine Creatinine Clearance Measurement in Potential Living Kidney Donors

Background

The accuracy of the measurement of renal function in potential living kidney donors (PLKD) is essential. The direct measurement of glomerular filtration rate (mGFR) has been considered the "gold standard." The estimated GFR (eGFR) with 24-hour urinary creatinine clearance (CrCl) is frequently used because of its availability. We aim to evaluate the correlation and agreement of eGFR using serum-based creatinine formulas (Cockcroft-Gault, MDRD, and CKD-EPI) and the eGFR based on 24-hour urinary CrCl to evaluate kidney function in PLKD.

Methods

We evaluated the kidney function in 799 PLKD using 24-hour urinary CrCl method and compared the correlation and agreement with the eGFR based on creatinine formulas (Cockcroft-Gault, MDRD, and CKD-EPI). We calculated the mean bias (difference), precision (SD of this difference), accuracy, and performed Bland-Altman plots.

Results

A total of 799 PLKD were analyzed. The age of the PLKD ranged from 18 to 73 years. Weak to mild correlation was observed between 24-hour urinary CrCl and all formulas (ranged from 0.31 to 0.49). The three equations underestimated the GFR. Using the Bland-Altman graphic, we observed that the CKD-EPI was the least scattered and most precise; however, mean bias and the interval range (limits of agreement) of all formulas were too big to assume equivalence between 24-hour urinary CrCl method and eGFR based on creatinine. Results of mean bias were similar when comparing the three equations in patients with CrCl GFR <60. However, the accuracy of all formulas was better for the female group and the youngest individuals (≤40 years old).

Conclusion

In this PLKD cohort, of all the three equations, the CKD-EPI was the least scattered and most precise. However, the correlation and the level of agreement between the three equations and 24-hour urinary CrCl were too low to assume the equivalence.

External Validation of the Toulouse-Rangueil Predictive Model to Estimate Donor Renal Function After Living Donor Nephrectomy

A predictive model to estimate post-donation glomerular filtration rate (eGFR) and risk of CKD at 1-year was developed from a Toulouse-Rangueil cohort in 2017 and showed an excellent correlation to the observed 1-year post-donation eGFR. We retrospectively analyzed all living donor kidney transplants performed at a single center from 1998 to 2020. Observed eGFR using CKD-EPI formula at 1-year post-donation was compared to the predicted eGFR using the formula eGFR (CKD-EPI, mL/min/1.73 m2) = 31.71+ (0.521 × preoperative eGFR) − (0.314 × age). 333 donors were evaluated. A good correlation (Pearson r = 0.67; p &lt; 0.001) and concordance (Bland-Altman plot with 95% limits of agreement −21.41–26.47 mL/min/1.73 m2; p &lt; 0.001) between predicted and observed 1-year post-donation eGFR were observed. The area under the ROC curve showed a good discriminative ability of the formula in predicting observed CKD at 1-year post-donation (AUC = 0.83; 95% CI: 0.78–0.88; p &lt; 0.001) with optimal cutoff corresponding to a predicted eGFR of 65.25 mL/min/1.73 m2 in which the sensibility and specificity to predict CKD were respectively 77% and 75%. The model was successfully validated in our cohort, a different European population. It represents a simple and accurate tool to assist in evaluating potential donors.