A Study of Renal Outcomes in Obese Living Kidney Donors

Impact of Age 70 years or Older on Donors for Living-Donor Kidney Transplantation

Introduction

Kidney transplantation (KT) involving elderly living kidney donors (LKDs) is becoming more frequent because of a profound organ shortage. The efficacy of KT involving grafts obtained from LKDs aged 70 years or older has been reported. However, the safety of donor nephrectomy in LKDs aged 70 years or older, including that associated with changes in the estimated glomerular filtration rate (eGFR), has not been investigated. This study investigated the outcomes of LKDs aged 70 years or older after donor nephrectomy.

Methods

This single-center, retrospective cohort study included 1226 LKDs who underwent donor nephrectomy between January 2008 and December 2020. LKDs were stratified into the following age groups: 30 to 49 years (244 LKDs), 50 to 69 years (803 LKDs), and 70 to 89 years (179 LKDs). Surgical outcomes, postoperative eGFR changes, end-stage renal disease (ESRD) rates, and mortality rates were compared among these groups.

Results

No significant difference in surgical outcomes was identified among the groups. LKDs aged 70 to 89 years experienced the lowest eGFR changes at all time points and the lowest eGFR improvement; however, ESRD was not identified in any group during the observation period. Mortality was the highest among LKDs aged 70 to 89 years compared to the other age groups.

Conclusion

Surgical outcomes, eGFR changes, and ESRD incidences can support the safety of donor nephrectomy in LKDs aged 70 years or older. Considering the advanced age, the high mortality rates in LKDs aged 70 years or older could be considered acceptable.

Patient-Level and Center-Level Factors Associated with Required Predonation Weight Loss among Obese Living Kidney Donors

Key Points

Among obese living kidney donors, year of donation, preoperative body mass index, hypertension, and center percent of living kidney donor transplants were associated with required predonation weight loss. There were no significant differences in the likelihood of predonation weight loss requirement by race, sex, or age or by markers of preoperative metabolic dysfunction.

Background

The proportion of overweight/mildly obese living kidney donors (OLKDs) has increased in the past few decades, with significant center variation in the body mass index (BMI) of LKDs. The purpose of this study was to examine factors associated with required predonation weight loss among OLKDs (BMI, ≥30 kg/m2).

Methods

This retrospective cohort study surveyed 1097 OLKDs (1979–2020) (mean BMI, 33 kg/m2) about their donation experience. Bivariate analyses compared donor demographic and center characteristics by whether the donor reported predonation weight loss requirement. Generalized estimating equations with logit link were used to estimate marginal effects of patient-level and center-level factors. Multiple imputation using chained equations was implemented to account for missing values.

Results

Of 1097 OLKDs surveyed, 340 (31.0%) reported predonation weight loss requirement. Donors with a predonation weight loss requirement had slightly higher predonation BMIs and donated in more recent years at centers performing a lower percentage of living donor nephrectomies and with a lower median BMI. In multivariable logistic regression analysis, we observed transplant year (odds ratio [OR], 1.04 per year donation; 95% confidence interval [CI], 1.01 to 1.07; P = 0.005), preoperative BMI (OR, 1.16; 95% CI, 1.05 to 1.28; P < 0.01), preoperative hypertension (OR, 1.61; 95% CI, 1.08 to 2.40; P = 0.02), and center percentage of living donor kidney transplants (OR, 0.99; 95% CI, 0.98 to 1.00; P = 0.02) as significantly associated with a predonation weight loss requirement. The study found no differences in the likelihood of predonation weight loss requirement by race, sex, age, preoperative creatinine, preoperative metabolic dysfunction, or center-level median BMI of living donors.

Conclusions

These results suggest that both center-level and patient-level factors influence whether OLKDs are required to lose weight before donation. Future study is needed to determine whether predonation weight loss is associated with improved long-term postdonation outcomes.

Prediction tool for renal adaptation after living kidney donation using interpretable machine learning

Introduction

Post-donation renal outcomes are a crucial issue for living kidney donors considering young donors' high life expectancy and elderly donors' comorbidities that affect kidney function. We developed a prediction model for renal adaptation after living kidney donation using interpretable machine learning.

Methods

The study included 823 living kidney donors who underwent nephrectomy in 2009-2020. AutoScore, a machine learning-based score generator, was used to develop a prediction model. Fair and good renal adaptation were defined as post-donation estimated glomerular filtration rate (eGFR) of ≥ 60 mL/min/1.73 m² and ≥ 65% of the pre-donation values, respectively.

Results

The mean age was 45.2 years; 51.6% were female. The model included pre-donation demographic and laboratory variables, GFR measured by diethylenetriamine pentaacetate scan, and computed tomography kidney volume/body weight of both kidneys and the remaining kidney. The areas under the receiver operating characteristic curve were 0.846 (95% confidence interval, 0.762-0.930) and 0.626 (0.541-0.712), while the areas under the precision-recall curve were 0.965 (0.944-0.978) and 0.709 (0.647-0.788) for fair and good renal adaptation, respectively. An interactive clinical decision support system was developed.

Conclusion

The prediction tool for post-donation renal adaptation showed good predictive capability and may help clinical decisions through an easy-to-use web-based application.

Preoperative Comorbidities and Outcomes of Medically Complex Living Kidney Donors

Introduction

Recent reports have described an increased risk of renal disease in living kidney donors compared with the general population. However, these reports do not detail the outcomes of medically complex living donors (MCLDs) with preoperative comorbidities (PCs), such as hypertension, dyslipidemia, glucose intolerance, and obesity. Analysis of living donors with end-stage renal disease (ESRD) has shown that these PCs may contribute significantly to the development of ESRD. We aimed to evaluate the effect of PCs on postoperative renal function and mortality in MCLDs.

Methods

Between January 2008 and December 2016, 807 living-donor kidney transplants were performed in our unit. Of these, 802 donors completed postoperative follow-up of >5 months. Donors were stratified into 4 groups based on the number of PCs present: healthy living donors (HLDs) with no PCs (n = 214) or MCLDs with 1 PC (n = 302), 2 PCs (n = 196), or 3 PCs (n = 90) (denoted MCLD [PC 1], MCLD [PC 2], or MCLD [PC 3], respectively). We compared pathology observation data from baseline biopsy, postoperative estimated glomerular filtration rate (eGFR), postoperative urinary protein concentration, and mortality between HLD and MCLD groups.

Results

Interstitial fibrosis, tubular atrophy, glomerulosclerosis, and arteriolosclerosis were more frequent in MCLDs (PC 3) than in HLDs. No significant differences were identified between HLDs and MCLDs in terms of postoperative eGFR and short-term mortality. Overt proteinuria and ESRD were not observed.

Conclusions

Appropriate postdonation management of MCLDs with PCs may result in similar outcomes as for HLDs.

Bariatric surgery for prospective living kidney donors with obesity?

The obesity epidemic has gripped the transplant community. With nearly 40% of adults in the United States being obese (BMI ≥30 kg/m² ) and 20% being morbidly obese (BMI ≥35 kg/m² ), the implications for both donors and recipients of solid organs continue to grow.¹ Nowhere is this more impactful than the candidacy of living kidney donors (LKDs). As increasing numbers of obese adults present for LKD consideration and evidence of inferior outcomes among obese LKDs grows, transplant surgeons will become progressively challenged by how to manage these patients in the clinic. Therefore, we offer this Personal Viewpoint to the transplant surgery community in order to review the current impact of obesity on living kidney donation, highlight what weight-loss interventions have already been attempted, and discuss the role that referral for weight-loss interventions including bariatric surgery might have going forward.

Kidney transplantation for the primary care provider

Advancement in kidney transplantation has led to prolonged survival in our population with kidney disease. Newer agents of immunosuppression have made this possible with less rejections and lesser opportunistic infections and transplant related deaths. Preventative care like timely vaccines, cancer screenings, aggressive blood pressure, blood sugar, lipid control, timely referral to consultants is required in these patient population to provide quality care and to prolong their survival. Primary care physicians are the best advocate for our transplant populations. To care for these complex transplant patients, it is vital for primary care physicians to be familiar with the overall approach on our patients.

Hand-Assisted Nephrectomy Predisposes Incisional Herniation in Obese Living Donors

BACKGROUND

Living kidney donation from donors with a body mass index (BMI) over 30 can bring risks for the donor and the recipients. In this retrospective study, we evaluated the effect of a donor's obesity on a donor's long-term surveillance and the recipient outcomes.

METHOD

We performed hand-assisted retroperitoneoscopic donor nephrectomy in 565 living kidney transplantations between February 2009 and December 2015. One hundred fifty-two donors (26.9%) had a BMI > 30 and were described as the obese group. Four hundred thirteen donors (73.1%) were described as the nonobese group and had a BMI < 30. Incision to kidney removal time, mean follow-up period, postoperative complications, weight gained after surgery, and serum creatinine level (postop day 1-end of follow-up) were recorded for the donors. Serum creatinine level (postop day 5-end of follow-up) and immediate function of transplanted kidney were recorded for the recipients.

RESULTS

The obese donors were older, and the female sex was dominant. Mean incision to kidney removal period was longer in the obese patients (P = .012). The mean follow-up period was 49.97 ± 28.40 months for the donors. There was no significant difference in donor kidney function between the groups. The incidence of herniation was significantly higher in the obese group (P = .021). There was no significant difference between the recipient early and late serum creatinine levels and slow and delayed graft functions after the transplantation.

CONCLUSION

Postoperative kidney functions concerning the outcomes of the obese and nonobese living donors were similar in our series. Donor BMI had no influence on early and late kidney functions of the recipients. There was no difference in postoperative complications, except incisional hernia, that was statistically more significant in the obese donors.

Early Hypertension and Diabetes After Living Kidney Donation: A National Cohort Study

BACKGROUND

Living kidney donors have an increased risk of end-stage renal disease, with hypertension and diabetes as the predominant causes. In this study, we sought to better understand the timeline when these diseases occur, focusing on the early postdonation period.

METHODS

We studied 41 260 living kidney donors in the United States between 2008 and 2014 from the Scientific Registry of Transplant Recipients and modeled incidence rates and risk factors for hypertension and diabetes.

RESULTS

At 6 months, 1 year, and 2 years postdonation, there were 74, 162, and 310 cases, respectively, of hypertension per 10 000 donors. Donors who were older (per 10 y, adjusted incidence rate ratio [aIRR], 1.40; 95% confidence interval [CI], 1.29-1.51), male (aIRR, 1.31; 95% CI, 1.14-1.50), had higher body mass index (per 5 units, aIRR, 1.29; 95% CI, 1.17-1.43), and were related to their recipient (first-degree relative: aIRR, 1.28; 95% CI, 1.08-1.52; spouse: aIRR, 1.34; 95% CI, 1.08-1.66) were more likely to develop hypertension, whereas donors who were Hispanic/Latino were less likely (aIRR, 0.71; 95% CI, 0.55-0.93). At 6 months, 1 year, and 2 years, there were 2, 6, and 15 cases of diabetes per 10 000 donors. Donors who were older (per 10 y: aIRR, 1.42; 95% CI, 1.11-1.82), had higher body mass index (per 5 units: aIRR, 1.52; 95% CI, 1.04-2.21), and were Hispanic/Latino (aIRR, 2.45; 95% CI, 1.14-5.26) were more likely to develop diabetes.

CONCLUSIONS

In this national study, new-onset diabetes was rare, but 3% of donors developed hypertension within 2 years of nephrectomy. These findings reaffirm that disease pathways for kidney failure differ by donor phenotype and estimate the population most at-risk for later kidney failure.

Clinical Impact of a Protocolized Kidney Donor Follow-up System

BACKGROUND

Adequate kidney donor management after donation is increasingly emphasized due to concerns of renal function impairment after nephrectomy with increasing life expectancy. In this study, the clinical impact of a protocolized kidney donor follow-up system by nephrologists was evaluated.

METHODS

A total of 427 living kidney donors underwent nephrectomy from January 2010 to December 2014 and were followed for at least 2 years at the Samsung Medical Center. Donors were followed-up by nephrologists after the establishment of a donor clinic with systemized protocols in January 2013. The primary outcomes were incidence of post-donation low estimated glomerular filtration rate (eGFR) and renal function adaptability. Secondary outcomes were changes in compliance and incidence of hyperuricemia and microalbuminuria.

RESULTS

The patients were divided into 2 groups according to the time of nephrectomy: the pre-donor clinic period (n = 182) and the donor clinic period (n = 172). Preoperative eGFR in patients in the pre-donor clinic period was higher than that in patients in the donor clinic period. After donation, poor renal adaptation was less frequent in the donor clinic period compared to the pre-donor clinic period. Low eGFR tended to be less common during the donor clinic period. Shorter mean outpatient clinic visit intervals with more visits within 6 months after donation and earlier detection of de novo hyperuricemia were found during the donor clinic period.

CONCLUSION

A protocolized donor clinic run by nephrologists may improve post-nephrectomy renal outcomes and compliance and facilitate better management of potential risk factors of chronic kidney disease in donors.

Living donor postnephrectomy kidney function and recipient graft loss: A dose-response relationship

Development of end-stage renal disease (ESRD) in living kidney donors is associated with increased graft loss in the recipients of their kidneys. Our goal was to investigate if this relationship was reflected at an earlier stage postdonation, possibly early enough for recipient risk prediction based on donor response to nephrectomy. Using national registry data, we studied 29 464 recipients and their donors from 2008-2016 to determine the association between donor 6-month postnephrectomy estimated GFR (eGFR) and recipient death-censored graft failure (DCGF). We explored donor BMI as an effect modifier, given the association between obesity and hyperfiltration. On average, risk of DCGF increased with each 10 mL/min decrement in postdonation eGFR (adjusted hazard ratio [aHR] 1.06, 95% confidence interval [CI] 1.02-1.10, P = .007). The association was attenuated with higher donor BMI (interaction P = .049): recipients from donors with BMI = 20 (aHR 1.12, 95% CI 1.04-1.19, P = .002) and BMI = 25 (aHR 1.07, 95% CI 1.03-1.12, P = .001) had a higher risk of DCGF with each 10 mL/min decrement in postdonation eGFR, whereas recipients from donors with BMI = 30 and BMI = 35 did not have a higher risk. The relationship between postdonation eGFR, donor BMI, and recipient graft loss can inform counseling and management of living donor kidney transplant recipients.

Long-Term Consequences of Complex Living Renal Donation: Is It Safe?

INTRODUCTION

As there is a paucity of literature regarding the long-term outcomes of complex living donors, we conducted this study to assess the effect of kidney donation on the complex living kidney donor.

MATERIALS AND METHODS

This retrospective study was conducted in Narayan Health Hospital, Kolkata, Eastern India. The cohort consisted of complex living kidney donors who donated kidneys between the years 2007 and 2012. All donors were 60 years old or older, or were younger than 60 years and had comorbidities like hypertension and obesity. After a minimum follow-up of 5 years, all donors underwent evaluation. Data pertaining to hypertension, new-onset diabetes, body mass index (BMI), estimated glomerular filtration rate (eGFR) and albuminuria, and cardiac events were compared from the time of donation till 5 years post-transplant.

RESULTS AND DISCUSSION

We found a statistically significant increase in blood pressure, number of antihypertensives used, and mean BMI at follow-up. Diabetes mellitus was developed in 22.3% of donors. The mean GFR also decreased significantly at follow-up. There were 42 elderly donors (≥60 years) and 23 ≤ 59 years of age. There was a significant fall of eGFR in both groups, but the percentage fall was similar in both groups. A significant percentage of donors developed proteinuria, the majority being hypertensives.

CONCLUSION

Procurement of kidneys from marginal donors should be done cautiously, and donors should be assessed for morbidity and mortality in the future, as we found a statistically significant deterioration in renal function, blood pressure, and BMI over long-term follow-up.

Impact of Preoperative Abdominal Visceral Adipose Tissue Area and Nutritional Status on Renal Function After Donor Nephrectomy in Japanese Living Donors for Renal Transplantation

BACKGROUND Living kidney donors face the risk of renal dysfunction, resulting in end-stage renal disease, cardiovascular disease, or cerebrovascular disease, after donor nephrectomy. Reducing this risk is important to increasing survival of living donors. In this study, we investigated the effect of preoperative distribution of abdominal adipose tissue and nutritional status on postoperative renal function in living donors. MATERIAL AND METHODS Seventy-five living donors were enrolled in this retrospective study. Preoperative unenhanced computed tomography images were used to measure abdominal adipose tissue parameters. Prognostic nutritional index (PNI) was used to assess preoperative nutritional status. Donors were divided into 2 groups according to abdominal visceral adipose tissue (VAT) area at the level of the fourth and fifth lumbar vertebrae (<80 or ≥80 cm²). Postoperative renal function was compared in the 2 groups, and prognostic factors for development of chronic kidney disease (CKD) G3b were identified using multivariate analysis. RESULTS Donors with a VAT area ≥80 significantly more often had hypertension preoperatively. Although there was no significant difference in preoperative estimated glomerular filtration rate (eGFR) between the 2 groups, postoperative renal function was significantly decreased in donors with a VAT area ≥80 compared to those with a VAT area <80. In multivariate analysis, VAT area ≥80 and PNI <54 were independent factors predicting the development of CKD G3b after 12 months. CONCLUSIONS Our findings suggest that preoperative VAT and PNI affect postoperative renal function. Further research is required to establish appropriate exercise protocols and nutritional interventions during follow-up to improve outcomes in living donors.

A multicenter cohort study of potential living kidney donors provides predictors of living kidney donation and non-donation

This multicenter prospective potential living kidney donor cohort study investigated which sociodemographic and other factors predict progression to living kidney donation or donor withdrawal as little is known on this topic. Therefore, we examined data on individuals undergoing living donor assessment at seven hospitals in the United Kingdom. Multivariable logistic regression was used to explore the relationships between donor and recipient characteristics and likelihood of kidney donation. A total of 805 individuals presented for directed donation to 498 intended recipients, of which 112 received a transplant from a living donor. Potential donors were less likely to donate if their intended recipient was female rather than male with an odds ratio of 0.60, a friend rather than relative 0.18, or had renal failure due to a systemic disease rather than another cause 0.41. The most socioeconomically deprived quintile was less likely to donate than the least 0.49, but the trend with deprivation was consistent with chance. Higher body mass index was associated with a lower likelihood of donation (odds ratio per each kg/m² increase, 0.92). Younger potential donors (odds ratio per each year increase 0.97), those of nonwhite ethnicity 2.98, and friend donors 2.43 were more likely to withdraw from work-up. This is the first study in the United Kingdom of potential living kidney donors to describe predictors of non-donation. Qualitative work with individuals who withdraw might identify possible ways of supporting those who wish to donate but experience difficulties doing so.

Laparoscopic vs open donor nephrectomy: Lessons learnt from single academic center experience

AIM

To compare laparoscopic and open living donor nephrectomy, based on the results from a single center during a decade.

METHODS

This is a retrospective review of all living donor nephrectomies performed at the Massachusetts General Hospital, Harvard Medical School, Boston, between 1/1998 - 12/2009. Overall there were 490 living donors, with 279 undergoing laparoscopic living donor nephrectomy (LLDN) and 211 undergoing open donor nephrectomy (OLDN). Demographic data, operating room time, the effect of the learning curve, the number of conversions from laparoscopic to open surgery, donor preoperative glomerular filtration rate and creatinine (Cr), donor and recipient postoperative Cr, delayed graft function and donor complications were analyzed. Statistical analysis was performed.

RESULTS

Overall there was no statistically significant difference between the LLDN and the OLDN groups regarding operating time, donor preoperative renal function, donor and recipient postoperative kidney function, delayed graft function or the incidence of major complications. When the last 100 laparoscopic cases were analyzed, there was a statistically significant difference regarding operating time in favor of the LLDN, pointing out the importance of the learning curve. Furthermore, another significant difference between the two groups was the decreased length of stay for the LLDN (2.87 d for LLDN vs 3.6 d for OLDN).

CONCLUSION

Recognizing the importance of the learning curve, this paper provides evidence that LLDN has a safety profile comparable to OLDN and decreased length of stay for the donor.

Clinical assessment of lipid profiles in live kidney donors

BACKGROUND

Abnormal serum lipid profiles are an issue in chronic kidney disease (CKD), but the clinical ramifications of dyslipidemia in live kidney donors are unclear. Thus, we explored the relationship between serum lipids and residual renal function in living donors post-nephrectomy.

METHODS

Charts of living donors who underwent nephrectomy between January 2010 and March 2013 were reviewed, targeting those with 6-month follow-up examinations at minimum. Altogether, 282 donors were studied, examining total cholesterol (TC), triglyceride (TG), low-density lipoprotein (LDL), and high-density lipoprotein (HDL) levels assayed before donation by standard techniques. Median follow-up time was 14 months. The relationship between postoperative renal function and allograft biopsy results was assessed. Recursive partitioning was applied to identify optimal cut-off points for each parameter.

RESULTS

Median (interquartile range) serum TC, TG, LDL, and HDL levels were 183 (161-205) mg/dL, 86 (63-131) mg/dL, 108 (92-128) mg/dL, and 53 (44-62) mg/dL, respectively. The glomerular filtration rate at last follow-up was associated with TC (r = -0.187; P = .002) and LDL (r = -0.172; P = .005) levels, but showed no correlation with TG and HDL. Root nodes of TC and LDL determinations in recursive partitioning were 170.5 mg/dL and 80.5 mg/dL, respectively, serving as thresholds for further evaluation. On logistic regression analysis, the likelihood of CKD (glomerular filtration rate < 60 mL/min/1.73 m(2)) at last follow-up was greater in donors with elevated TC and LDL levels (odds ratio = 1.96 and 3.33; P = .021 and .029, respectively).

CONCLUSION

Kidney donors with serum TC and LDL elevations require close observation, given their demonstrable predisposition to CKD after donation.

Weight trends in United States living kidney donors: Analysis of the UNOS database

AIM: To analyze the national trends associated with body mass index (BMI) and living kidney donation.

METHODS: Forty-seven thousand seven hundred and five adult living kidney donors as reported to the Organ Procurement and Transplantation Network from 1999 to 2011 were analyzed using their pre-donation BMI. Predictor variables of interest included age, gender, ethnicity, relationship, education status, and transplant region.

RESULTS: Sixteen thousand nine hundred and seventy-one of the living kidney donors were normal weight (35.6%); 19337 were overweight (40.5%); 9007 were mildly obese (18.9%); 1992 were moderate to morbidly obese (4.2%). Overweight and mildly obese kidney donors have increased through time by 12% and 20% every 5 years, respectively (P < 0.05). Donors 35-49 years of age, hispanic males or females and black females, those with high school diploma or general Education Degree, and biologically related or partner/spouses were more likely to be obese.

CONCLUSION: Over the past 13 years, the majority of living kidney donors have spanned the overweight to obese categories. Paralleling the national rise is an increase in overweight and mildly obese kidney donors. A fair number of moderate to morbidly obese living kidney donors are still allowed to donate.

Evaluating the Impact of Performance Improvement Initiatives on Transplant Center Reporting Compliance and Patient Follow-Up After Living Kidney Donation

With the changing demographics of the living donor population and increased regulatory oversight, it is important that transplant centers report outcomes accurately. The aim of our retrospective cohort study of 312 living donors who underwent nephrectomy between 2008 and 2013 was to evaluate the impact of living donor program performance improvement initiatives on: (i) transplant center program reporting compliance; (ii) patient compliance with postdonation follow-up and its associated factors; and (iii) overall financial costs to the transplant center. The effect of the initiatives (donation eras 2008-2010 and 2011-2013) on compliance at key reporting points (6 months, 1 year, 2 years) was analyzed using correlation coefficients, χ(2) and Fisher's exact tests. Multivariable logistic regression models tested the initiatives' effect on the likelihood of patient follow-up. The initiatives were associated with significant improvement in form reporting compliance (r ≥ 0.862, p ≤ 0.027; 1 and 2 year Fisher's Exact p ≤ 0.002) and patient follow-up (χ(2) p ≤ 0.009) with acceptable transplant center costs. Multivariable analyses demonstrated that donation era was consistently and significantly (p < 0.001) associated with increased likelihood of postdonation patient follow-up. Institution of performance improvement initiatives with dedicated program resources is financially feasible and leads to more accurate and complete form reporting and improved patient follow-up after nephrectomy.

Renal blood flow using arterial spin labelling MRI and calculated filtration fraction in healthy adult kidney donors Pre-nephrectomy and post-nephrectomy

OBJECTIVES

Renal plasma flow (RPF) (derived from renal blood flow, RBF) and glomerular filtration rate (GFR) allow the determination of the filtration fraction (FF), which may have a role as a non-invasive renal biomarker. This is a hypothesis-generating pilot study assessing the effect of nephrectomy on renal function in healthy kidney donors.

METHODS

Eight living kidney donors underwent arterial spin labelling (ASL) magnetic resonance imaging (MRI) and GFR measurement prior to and 1 year after nephrectomy. Chromium-51 labelled ethylenediamine tetraacetic acid ((51)Cr-EDTA) with multi-blood sampling was undertaken and GFR calculated. The RBF and GFR obtained were used to calculate FF.

RESULTS

All donors showed an increase in single kidney GFR of 24 - 75 %, and all but two showed an increase in FF (-7 to +52 %) after nephrectomy. The increase in RBF, and hence RPF, post-nephrectomy was not as great as the increase in GFR in seven out of eight donors. As with any pilot study, the small number of donors and their relatively narrow age range are potential limiting factors.

CONCLUSIONS

The ability to measure RBF, and hence RPF, non-invasively, coupled with GFR measurement, allows calculation of FF, a biomarker that might provide a sensitive indicator of loss of renal reserve in potential donors.

KEY POINTS

• Non-invasive MRI measured renal blood flow and calculated renal plasma flow. • Effect of nephrectomy on blood flow and filtration in donors is presented. • Calculated filtration fraction may be a useful new kidney biomarker.

Obesity Correlates With Glomerulomegaly But Is Not Associated With Kidney Dysfunction Early After Donation

BACKGROUND

Body mass index (BMI) is a convenient measure used to assess obesity and is used to select candidates for kidney donation. Glomerulomegaly is an early indicator of obesity-related kidney disease. Whether obesity assessment by BMI best reflects underlying glomerulomegaly and is predictive of adverse changes in renal function postdonation is unclear.

METHODS

We performed a retrospective study on a cohort of 1065 living donors at the Mayo Clinic in Rochester; obesity measures by BMI and by computed tomography were compared between 20 donors with largest to 20 donors with the smallest glomerular volumes (on implantation biopsy). In addition, the change in kidney function postdonation (mean 7 months) was compared across BMI groups (<25, 25-29, 30-34, ≥35 kg/m²) in about 500 donors.

RESULTS

We observed that larger glomerular volume was more strongly associated with BMI per standard deviation (SD) (odds ratio [OR] =5.0, P = 0.002) than waist circumference/height² per SD (OR = 3.9, P = 0.02), visceral fat/height² per SD (OR = 2.4, P = 0.02), subcutaneous fat/height² per SD (OR = 2.0, P = 0.06), renal hilar fat/height² per SD (OR = 1.6, P = 0.19), or peri/pararenal fat/height² per SD (OR = 1.5, P = 0.23). Postdonation changes in glomerular filtration rate, blood pressure, and albuminuria were similar across BMI categories.

CONCLUSIONS

The BMI outperforms various computed tomography measures of abdominal fat in detecting obesity-related glomerulomegaly. Despite this strong association with glomerulomegaly, short-term renal function outcomes are similar across BMI categories. Long-term follow-up is required to definitively define the impact of obesity on kidney function after donation.

Consistency of racial variation in medical outcomes among publicly and privately insured living kidney donors

BACKGROUND

Racial disparities in health outcomes after living donation have been reported, but generalizability is not known.

METHODS

We linked Organ Procurement and Transplantation Network (OPTN) registry data for 4,007 living kidney donors in 1987 to 2008 with Medicare billing claims (2000-2008). Cox regression with left and right censoring was used to estimate the frequencies and relative risks of postdonation medical diagnoses according to race. Patterns were compared with findings from a previous linkage of OPTN donor records and private insurance claims.

RESULTS

Among the Medicare-insured donors, 8% were African American and 5.7% were Hispanic. Diagnosis frequencies at 5 years after donation in the Medicare- versus privately insured donors included the following: malignant hypertension, 5.0% versus 0.9%; diabetes, 18.5% versus 4.1%; and chronic kidney disease, 21.8% versus 4.9%. After age and sex adjustment in the Medicare sample, African Americans, as compared with white donors, experienced higher risks of any hypertension diagnosis, including 2.4 times the likelihood of malignant hypertension (adjusted hazard ratio [aHR], 2.35; 95% confidence interval [CI], 1.40-3.93), and more common diabetes (aHR, 1.50; 95% CI, 1.12-2.04), chronic kidney disease (aHR, 1.84; 95% CI, 1.37-2.47), and proteinuria (aHR, 2.44; 95% CI, 1.45-4.11) diagnoses. Relative patterns for privately insured African American versus white donors were similar, including approximately three times the risk of malignant hypertension (aHR, 3.27; 95% CI, 1.82-5.88) and twice the relative risks of chronic kidney disease and proteinuria.

CONCLUSIONS

Consistent demonstration of racial variation in postdonation medical conditions regardless of sample/payer source supports the need for continued study of mediators and consequences of outcomes in non-white donors.

Nutrition assessment and counseling of the medically complex live kidney donor

Kidney transplantation is the preferred option for patients with end-stage renal disease facing the need for dialysis because it provides maximum survival benefit. The number of people seeking kidney transplantation greatly exceeds available deceased donor organs. Organs from live donors provide a survival advantage over organs from deceased donors while also broadening the pool of available organs. The purpose of this review is to discuss the clinical guidelines that pertain to live kidney organ donation and to describe the nutrition evaluation and care of live kidney donors. The process for living kidney donation is dictated by policies centered on protecting the donor. In a perfect world, the living donor would present with a flawless medical examination and a benign family health history. The obesity epidemic has emerged as a major health concern. Live donor programs are faced with evaluating increasing numbers of obese candidates. These "medically complex donors" may present with obesity and its associated comorbid conditions, including hypertension, impaired glycemic control, and kidney stone disease. The dietitian's role in the live donor program is not well defined. Participation in the living donor selection meeting, where details of the evaluation are summarized, provides a platform for risk stratification and identification of donors who are at increased lifetime risk for poor personal health outcomes. Guiding the donor toward maintenance of a healthy weight through diet and lifestyle choices is a legitimate goal to minimize future health risks.

Obesity and metabolic syndrome in kidney transplantation

The epidemic of obesity and metabolic syndrome (MS) contributes to the rapid growth of chronic kidney disease (CKD) and end-stage renal disease (ESRD). There is a reverse epidemiology, known as the "obesity paradox," in ESRD patients receiving maintenance dialysis. Obese patients are routinely referred for kidney transplant, and they have more surgical and medical complications than non-obese patients. However, compared to dialysis, kidney transplant provides a survival benefit for obese patients. After kidney transplant, obese patients tend to gain more body weight, and non-obese patients can develop new-onset obesity/MS. Obesity/MS is not only associated with serious morbidities, but also compromises the long-term graft and patient survival. The immunosuppressive drugs commonly used as maintenance therapy, including corticosteroids, calcineurin inhibitors and mammalian target-of-rapamycin inhibitors, contribute to obesity/MS. Development of novel immunosuppressive drugs free of metabolic adverse effects is needed, so that the full potential and benefits of kidney transplantation can be realized.

Health-related quality of life in kidney donors from the last five decades: results from the RELIVE study

Live donation benefits recipients, but the long-term consequences for donors remain uncertain. Renal and Lung Living Donors Evaluation Study surveyed kidney donors (N = 2455; 61% women; mean age 58, aged 24-94; mean time from donation 17 years, range 5-48 years) using the Short Form-36 Health Survey (SF-36). The 95% confidence intervals for White and African-American donors included or exceeded SF-36 norms. Over 80% of donors reported average or above average health for their age and sex (p < 0.0001). Donors' age-sex adjusted physical component summary (PCS) scores declined by half a point each decade after donation (p = 0.0027); there was no decline in mental component summary (MCS) scores. White donors' PCS scores were three points higher (p = 0.0004) than non-Whites'; this difference remained constant over time. Nine percent of donors had impaired health (PCS or MCS score >1 SD below norm). Obesity, history of psychiatric difficulties and non-White race were risk factors for impaired physical health; history of psychiatric difficulties was a risk factor for impaired mental health. Education, older donation age and a first-degree relation to the recipient were protective factors. One percent reported that donation affected their health very negatively. Enhanced predonation evaluation and counseling may be warranted, along with ongoing monitoring for overweight donors.

Obesity as a barrier to living kidney donation: a center-based analysis

BACKGROUND

Obesity is a major epidemic and may present a significant barrier to living kidney donation. The purpose of our study was to determine the frequency of obesity as an exclusion factor and assess how often these donors lose weight and donate.

METHODS

A single center, retrospective analysis of 104 potential living kidney donors between 2008 and 2012.

RESULTS

Of the 104 donors, 19 (18%) had a normal body mass index (BMI) of <25. Eighty-five of the 104 (82%) donors spanned the overweight to morbidly obese classifications. Thirty-eight (37%) were overweight (BMI 25-29.9). Twenty-four (23%) were categorized as class I obesity (BMI 30-34.9), 17 (16%) as class II obesity (BMI 35-39.9), and six (6%) as class III obesity (BMI >40). There were a total of 23 donors (22%) who were considered moderately and morbidly obese (BMI >35). Of these, only three (13%) succeeded at losing weight and donating.

CONCLUSIONS

Obesity may be a frequent barrier to living kidney donation, directly leading to exclusion as a potential kidney donor in about one in five instances. Successful weight loss leading to donation appears to be infrequent, suggesting need to address obesity in the donor population.

Renal function and cardiovascular outcomes after living donor nephrectomy in the UK: quality and safety revisited

OBJECTIVE

To determine renal function and cardiovascular outcomes after living donor nephrectomy (LDN). Living donor kidney transplantation has become established as the treatment of choice for end-stage renal failure. Benefits to the recipient have to be balanced against perioperative and long-term health risks to the donor.

SUBJECTS/PATIENTS AND METHODS

The UK Transplant Registry (UKTR) was used to identify 4586 living donors who had donated a kidney for transplantation in the UK between 2001 and 2008. This study was conducted with the consent and support of the NHS Blood and Transplant (NHSBT) Kidney and Pancreas Research Group.

RESULTS

The mean glomerular filtration rate (GFR) fell from 103 mL/min/1.73 m(2) before LDN to 58 mL/min/1.73 m(2) 1 year after LDN. At 1 year after LDN 60% of donors had a GFR of <60 mL/min/1.73 m(2). A GFR of <60 mL/min/1.73 m(2) after LDN was associated with older age, females, lower GFR before LDN, White ethnicity, earlier LDN period, unrelated donor type and body mass index of >25 kg/m(2). Over a 2-year period after LDN there was an overall mortality rate of 0.39%, cardiovascular death in one patient (mortality rate of 0.02%) and a major cardiovascular event rate of 0.44%.

CONCLUSION

In this study we show that mild renal dysfunction is common after LDN; however, due to the short duration of follow-up we are unable to comment on whether this subsequently leads to an increased risk of developing of cardiovascular disease.

Does a nephron deficit exacerbate the renal and cardiovascular effects of obesity?

It has been hypothesized that a reduced nephron endowment exacerbates the hypertensive and renal effects of obesity. We therefore examined the impact of diet-induced obesity on renal structure and function, and arterial pressure in a genetic model of reduced nephron endowment, the GDNF Heterozygous (HET) mouse. 6wk-old male GDNF WT and HET mice were placed on control or high fat (HFF) diet for 20 weeks. 24 hr arterial pressure, heart rate and activity (radiotelemetry), creatinine clearance and albumin excretion were measured, and kidneys collected (histopathology, collagen content). Bodyweights of HFF WT (50.6±1.2 g) and HET (48.8±1.4 g) mice were ∼14 g greater than control mice (37.3±1.3 g, 36.4±1.1 g respectively; Pdiet<0.001). Obesity led to significantly greater 24 hr MAP (Pdiet<0.001), heart rate (Pdiet<0.01) and lower locomotor activity (Pdiet<0.01) in HET and WT mice. Whilst there was no significant impact of genotype on 24 hr MAP response to obesity, night-time MAP of obese HET mice was significantly greater than obese WT mice (122.3±1.6 vs 116.9±1.3 mmHg; P<0.05). 24 hr creatinine clearance was 50%, and albumin excretion 180% greater in obese WT and HET mice compared to controls (Pdiet<0.05) but this response did not differ between genotypes. Obesity induced glomerulomegaly, glomerulosclerosis, tubulointerstitial expansion and increased collagen accumulation (total, collagen I, V and IV; Pdiet<0.001). Obese GDNF HET mice had exacerbated total renal collagen (P<0.01), and greater levels of the collagen I subtype compared to kidneys of obese WT mice. In summary, obese nephron-deficient GDNF HET mice were able to maintain the high creatinine clearances of obese WT mice but at the expense of higher MAP and greater renal fibrosis. Whilst modest, our findings support the hypothesis that a reduced nephron endowment increases the susceptibility to obesity-induced kidney disease and hypertension.

Transplantation ethics: are we approaching the crossroads?

Ethical issues of organ transplantation are of extreme importance to involved physicians and to society. The basic principle is that the donor cannot be considered as a commodity; financial incentives must not occur. Regarding deceased-donor organ transplantations, ethical issues are related to the consent for donation, determination of death, and principles of organ allocation. Living donors should be healthy, giving free consent after being fully informed about the risks of the procedure. Transplant professionals have a double responsibility because they must remember about the rights of the organ recipient as well as of the donor. Because of the organ shortage we commonly use organ recovery from donors after cardiac arrest and extend the living-donor pool, practices that may influence some important ethical principles. A proper detailed determination of donor death is of utmost importance. The dead donor rule must be preserved. However category III non-heart-beating donors (so-called controlled cardiac arrest) raise doubts as to the time of the decision to transfer the dying (not yet dead) patient to the operating room to withhold supportive treatment. In certain centers, not quite healthy living donors are being used; they are called extended-criteria or complex donors. Although organ trade is condemned, some workers agree to use as complete strangers donors, obviously believing in pure altruistic motivation of such donors without the additional incentives. Finally, is the trend to consider utility in organ allocation justified? It seems that quite soon we may need a new transplantation ethics code that is not totally directed by transplant professionals exclusively to the needs of potential recipients.

Safety of nephrectomy in morbidly obese donors

OBJECTIVES

To satisfy donor organ shortage, overweight and obese donors are becoming a greater proportion of the kidney donor pool. Although good safety data exist in overweight and moderately obese individuals (body mass index = 25 to 35 kg/m²), there is little information about outcomes in morbidly obese donors (body mass index ≥ 40 kg/m²). The purpose of this study was to review the experience with morbidly obese donors in a single center and assist in the discussion about the feasibility of nephrectomy in such cases.

MATERIALS AND METHODS

Outcomes of nephrectomy in morbidly obese donors between January 2005 and June 2010 were reviewed retrospectively and compared with outcomes in nonobese donors.

RESULTS

Of 386 nephrectomies, 7 involved morbidly obese donors. Mortality and major complication rates were low in all body mass index categories. A high incidence of minor postoperative complications was observed in the morbidly obese, with 57% morbidly obese patients requiring treatment for complications including respiratory infection, compared with 30% in nonobese donors (P < .05). There were no significant differences in mean operative time, estimated blood loss, and length of hospital stay between all body mass index categories. Limited follow-up data (mean, 20 mo) showed similar renal function parameters between groups.

CONCLUSIONS

The limited data suggest that nephrectomy may be feasible in selected morbidly obese donors. Further study is needed before major conclusions can be made.

Living kidney donor follow-up: state-of-the-art and future directions

Long-term living kidney donor follow-up has not been considered necessary by many living kidney donor programs because a large number of single-center studies show that living kidney donation is associated with minimal mortality and morbidity. However, some transplant professionals and, more importantly, living donors disagree. To evaluate the need for more data on living kidney donor outcomes, a conference was held in September 2010 (Leichtman and colleagues: Am J Transplant 11: 2561-2568, 2011). Participants were health care professionals, living donors, members of the United Network for Organ Sharing, Health and Human Services, the National Institutes of Health, and insurance companies. This article will discuss the status of living donor follow-up in the context of the follow-up conference. It will also provide a slightly different viewpoint of provider responsibility for donor follow-up than that presented by the conference report.

Risks and outcomes of living donation

Living donors supply approximately 40% of renal allografts in the United States. Based on current data, perioperative mortality after donor nephrectomy is approximately 3 per 10,000 cases, and major and minor perioperative complications affect approximately 3% to 6% and 22% of donors, respectively. Donor nephrectomy does not appear to increase long-term mortality compared with controls, nor does it appear to increase ESRD risk among white donors. Within the donor population, the likelihood of postdonation chronic renal failure and medical comorbidities such as hypertension and diabetes appears to be relatively higher among some donor subgroups, such as African Americans and obese donors, but the impact of uninephrectomy on the lifetime risks of adverse events expected without nephrectomy in these subgroups has not yet been defined. As national follow-up of living donors in the United States is limited in scope, duration, and completeness, additional methods for quantifying risk among diverse living donors are needed. In addition to improved national collection of follow-up data, possible sources of information on donor outcomes may include focused studies with carefully defined control groups, and database integration projects that link national donor registration records to other data sources. Given the growth and evolving characteristics of the living donor population, as well as changes in surgical techniques, tracking of short- and long-term risks after living kidney donation is vital to support truly informed consent and to maintain public trust in living donation. The transplant community must persist in their efforts to accurately assess risk across demographically diverse living kidney donors.

Expanding the donor pool: living donor nephrectomy in the elderly and the overweight

BACKGROUND

Increasing demand for donor kidneys, in parallel with trends toward more elderly and obese populations, make it important to continuously review donor pool inclusion criteria. Acceptance of elderly and obese living donors remains controversial, with a higher incidence of comorbidity and the greater risk of postoperative complications sighted as reasons for caution. Drawing on our center's experience, we aim to determine whether older age and obesity are in fact associated with greater perioperative risk, and longer term complications in donors undergoing nephrectomy.

METHODS

Three hundred eighty-three living donor nephrectomies conducted at one of the United Kingdom's largest transplant units over the last 5 years were stratified into groups according to age and body mass index. Perioperative endpoints and postdonation follow-up data collected at 6-to-12-monthly intervals were analyzed and compared.

RESULTS

No significant differences in operative parameters, including operative time and estimated blood loss, were reported between groups. Rates of early postoperative complications were not significantly different, although subgroup analysis showed a higher incidence of respiratory complications at the extremes of obesity (body mass index ≥ 40 kg/m²). On follow-up, renal function parameters showed significant change postnephrectomy, but between-group variation was not significant. Mortality and major complication rates were comparably low in all groups of study.

CONCLUSIONS

In our unit's experience, nephrectomy in selected donors who may otherwise have been precluded from participation on account of their age or weight, is feasible and associated with perioperative and longer term outcomes comparable with their younger nonobese counterparts. It provides a basis for informed consent of "extended criteria" donors.

Racial differences in outcomes of the evaluation of potential live kidney donors: a retrospective cohort study

BACKGROUND

In the USA, the lower rate of live donor kidney transplant among Black transplant candidates may stem from lower rates of donation among potential live donors who are Black. We determined whether outcomes of the evaluation of potential live kidney donors varied according to the potential donors' demographic characteristics.

METHODS

We performed a single-center, retrospective observational cohort study of 1,179 potential live kidney donors, who came forward between 2000 and 2007. Potential donors' intended recipients were first-time transplant recipients who were evaluated between 2000 and 2005.

RESULTS

There were 268 (22.7%) potential live kidney donors who were Black, of whom 93.7% were recruited by Black transplant candidates. Donor outcomes included actual donation (38.3%), exclusion due to blood group or crossmatch incompatibility (20.4%), exclusion due to medical contraindication to donation (13.7%), and lack of further donor interest (11.2%). Black (vs. non-Black) potential donors were less likely to actually donate (27.2 vs. 41.6%, p < 0.001). Black potential donors were more likely to stop pursuing live donation (p = 0.047) or be excluded from donation for medical reasons (p = 0.008) or blood group or crossmatch incompatibility (p = 0.01). These racial differences persisted in a multivariable multinomial logistic regression model of factors associated with outcomes of the donor evaluation.

CONCLUSIONS

Potential live kidney donors who are Black are less likely to actually donate. Future studies should determine whether paired exchange and desensitization programs decrease these racial differences and why Black potential donors appear more likely to stop pursuing live donation.

Long-term outcomes of kidney donors

PURPOSE OF REVIEW

Living kidney donors face a unique decision of self-sacrifice that is not without potential risk. The purpose of this review is to highlight existing research regarding the perioperative morbidity, mortality and long-term outcomes of living kidney donors.

RECENT FINDINGS

Recent studies of long-term donor survival have affirmed that the life expectancy for living kidney donors is excellent and their risk of end-stage renal disease (ESRD) is not increased. Long-term health outcomes for living donors representing minority groups, however, may not be as favorable. Recent studies conclude that African-American and Hispanic donors, similarly to nondonors of the same race, are at higher risk of developing chronic kidney disease (CKD), hypertension, and diabetes mellitus. Outcomes in medically complex donors have also generated considerable attention, and the evidence on outcomes among otherwise healthy obese and older donors appears to be reassuring.

SUMMARY

Living kidney donation is a superior transplantation option for many individuals with ESRD. The survival and health consequences of living donation have proven to be excellent. These favorable outcomes stem from careful screening measures, and further research endeavors are needed to ensure long-term living donor safety in high-risk donors.

99mTc-MAG3 scintigraphy for the longitudinal follow-up of kidney function in a mouse model of renal ischemia-reperfusion injury

Background

Experimental models are essential tools in the development and evaluation of novel treatment options, but the preclinical model of renal ischemia-reperfusion injury is limited to the retrieval of (very) early functional data, leaving the pivotal long-term outcome unknown. The present study applies technetium-99m-mercapto-acetyl-tri-glycine [^99mTc-MAG3] scintigraphy for the longitudinal follow-up examination of long-term kidney function after renal ischemia-reperfusion injury.

Methods

Unilateral warm ischemia was induced in scid beige mice by vascular clamping of the kidney hilum for 40 min. ^99mTc-MAG3 scintigraphy was performed prior to injury, 8 and 14 days post ischemia. The fractional uptake rate [FUR] was calculated from scintigraphy data as a measure of renal clearance.

Results

FUR demonstrated a significant functional impairment of the ischemic kidney 8 and 14 days after injury (P < 0.05 vs. baseline), while contralateral non-ischemic kidneys showed no significant changes. In histological analysis, ischemic kidneys exhibited tubular dilatation and cytoplasmic degeneration as signs of hypoxia without any evidence for necrosis.

Conclusions

FUR enables the detection of renal dysfunction and longitudinal long-term follow-up examination in the same individual. Our model may facilitate preclinical therapy evaluation for the identification of effective renoprotective therapies.

Controversies related to living kidney donors

Background

Increasing the living-donor pool by accepting donors with an isolated medical abnormality (IMA) can significantly decrease the huge gap between limited supply and rising demand for organs. There is a wide range of variation among different centres in dealing with these categories of donors. We reviewed studies discussing living kidney donors with IMA, including greater age, obesity, hypertension, microscopic haematuria and nephrolithiasis, to highlight the effect of these abnormalities on both donor and recipient sides from medical and surgical perspectives.

Methods

We systematically searched MEDLINE, ISI Science Citation Index expanded, and Google scholar, from the inception of each source to January 2011, using the terms ‘kidney transplant’, ‘renal’, ‘graft’, ‘living donor’, ‘old’, ‘obesity’, ‘nephrolithiasis’, ‘haematuria’ and ‘hypertension’. In all, 58 studies were found to be relevant and were reviewed comprehensively.

Results

Most of the reviewed studies confirmed the safety of using elderly, moderately obese and well-controlled hypertensive donors. Also, under specific circumstances, donors with nephrolithiasis can be accepted. However, persistent microscopic haematuria should be considered seriously and renal biopsy is indicated to exclude underlying renal disease.

Conclusion

Extensive examination and cautious selection with tailored immunosuppressive protocols for these groups can provide a satisfactory short- and medium-term outcome. Highly motivated elderly, obese, controlled hypertensive and the donor with a unilateral small stone (<1.5 cm, with normal metabolic evaluation) could be accepted. Donors with dysmorphic and persistent haematuria should not be accepted. A close follow-up after donation is crucial, especially for obese donors who developed microalbuminuria.

Living kidney donor follow-up: state-of-the-art and future directions, conference summary and recommendations

In light of continued uncertainty regarding postkidney donation medical, psychosocial and socioeconomic outcomes for traditional living donors and especially for donors meeting more relaxed acceptance criteria, a meeting was held in September 2010 to (1) review limitations of existing data on outcomes of living kidney donors; (2) assess and define the need for long-term follow-up of living kidney donors; (3) identify the potential system requirements, infrastructure and costs of long-term follow-up for living kidney donor outcomes in the United States and (4) explore practical options for future development and funding of United States living kidney donor data collection, metrics and endpoints. Conference participants included prior kidney donors, physicians, surgeons, medical ethicists, social scientists, donor coordinators, social workers, independent donor advocates and representatives of payer organizations and the federal government. The findings and recommendations generated at this meeting are presented.