A Case-Based Analysis of Whether Living Related Donors Listed for Transplant Share ESRD Causes with Their Recipients

Development and Validation of a Hypertension Risk Calculator for Living Kidney Donors

BACKGROUND

Ideally, when deciding whether to donate, kidney donor candidates would understand their long-term risks. Using single-center data (N = 4055; median [quartiles] follow-up: 18 [9-28] y), we developed a calculator for postdonation hypertension and validated it using long-term data from an external single-center cohort (N = 1189, median [quartiles] follow-up: 9 [5-17] y).

METHODS

Risk factors considered were routinely obtained at evaluation from donor candidates. Two modeling approaches were evaluated: Cox proportional hazards and random survival forest models. Cross-validation prediction error and Harrell's concordance-index were used to compare accuracy for model development. Top-performing models were assessed in the validation cohort using the concordance-index and net reclassification improvement.

RESULTS

In the development cohort, 34% reported hypertension at a median (quartiles) of 16 (8-24) y postdonation; and in the validation cohort, 29% reported hypertension after 17 (10-22) y postdonation. The most accurate model was a Cox proportional hazards model with age, sex, race, estimated glomerular filtration rate, systolic and diastolic blood pressure, body mass index, glucose, smoking history, family history of hypertension, relationship with recipient, and hyperlipidemia (concordance-index, 0.72 in the development cohort and 0.82 in the validation cohort).

CONCLUSIONS

A postdonation hypertension calculator was developed and validated; it provides kidney donor candidates, their family, and care team a long-term projection of hypertension risk that can be incorporated into the informed consent process.

The Minnesota attributable risk of kidney donation (MARKD) study: a retrospective cohort study of long-term (> 50 year) outcomes after kidney donation compared to well-matched healthy controls

BACKGROUND

There is uncertainty about the long-term risks of living kidney donation. Well-designed studies with controls well-matched on risk factors for kidney disease are needed to understand the attributable risks of kidney donation.

METHODS

The goal of the Minnesota Attributable Risk of Kidney Donation (MARKD) study is to compare the long-term (> 50 years) outcomes of living donors (LDs) to contemporary and geographically similar controls that are well-matched on health status. University of Minnesota (n = 4022; 1st transplant: 1963) and Mayo Clinic LDs (n = 3035; 1st transplant: 1963) will be matched to Rochester Epidemiology Project (REP) controls (approximately 4 controls to 1 donor) on the basis of age, sex, and race/ethnicity. The REP controls are a well-defined population, with detailed medical record data linked between all providers in Olmsted and surrounding counties, that come from the same geographic region and era (early 1960s to present) as the donors. Controls will be carefully selected to have health status acceptable for donation on the index date (date their matched donor donated). Further refinement of the control group will include confirmed kidney health (e.g., normal serum creatinine and/or no proteinuria) and matching (on index date) of body mass index, smoking history, family history of chronic kidney disease, and blood pressure. Outcomes will be ascertained from national registries (National Death Index and United States Renal Data System) and a new survey administered to both donors and controls; the data will be supplemented by prior surveys and medical record review of donors and REP controls. The outcomes to be compared are all-cause mortality, end-stage kidney disease, cardiovascular disease and mortality, estimated glomerular filtration rate (eGFR) trajectory and chronic kidney disease, pregnancy risks, and development of diseases that frequently lead to chronic kidney disease (e.g. hypertension, diabetes, and obesity). We will additionally evaluate whether the risk of donation differs based on baseline characteristics.

DISCUSSION

Our study will provide a comprehensive assessment of long-term living donor risk to inform candidate living donors, and to inform the follow-up and care of current living donors.

Recommendations for living donor kidney transplantation

This Guide for Living Donor Kidney Transplantation (LDKT) has been prepared with the sponsorship of the Spanish Society of Nephrology (SEN), the Spanish Transplant Society (SET), and the Spanish National Transplant Organization (ONT). It updates evidence to offer the best chronic renal failure treatment when a potential living donor is available. The core aim of this Guide is to supply clinicians who evaluate living donors and transplant recipients with the best decision-making tools, to optimise their outcomes. Moreover, the role of living donors in the current KT context should recover the level of importance it had until recently. To this end the new forms of incompatible HLA and/or ABO donation, as well as the paired donation which is possible in several hospitals with experience in LDKT, offer additional ways to treat renal patients with an incompatible donor. Good results in terms of patient and graft survival have expanded the range of circumstances under which living renal donors are accepted. Older donors are now accepted, as are others with factors that affect the decision, such as a borderline clinical history or alterations, which when evaluated may lead to an additional number of transplantations. This Guide does not forget that LDKT may lead to risk for the donor. Pre-donation evaluation has to centre on the problems which may arise over the short or long-term, and these have to be described to the potential donor so that they are able take them into account. Experience over recent years has led to progress in risk analysis, to protect donors' health. This aspect always has to be taken into account by LDKT programmes when evaluating potential donors. Finally, this Guide has been designed to aid decision-making, with recommendations and suggestions when uncertainties arise in pre-donation studies. Its overarching aim is to ensure that informed consent is based on high quality studies and information supplied to donors and recipients, offering the strongest possible guarantees.

Long-term Medical Outcomes of Living Kidney Donors

Historically, to minimize risks, living kidney donors have been highly selected and healthy. Operative risks are well-defined, yet concern remains about long-term risks. In the general population, even a mild reduction in glomerular filtration rate (GFR) is associated with cardiovascular disease, chronic kidney disease, and end-stage kidney disease (ESKD). However, reduction in GFR in the general population is due to kidney or systemic disease. Retrospective studies comparing donors with matched general population controls have found no increased donor risk. Prospective studies comparing donors with controls (maximum follow-up, 9 years) have reported that donor GFR is stable or increases slightly, whereas GFR decreases in controls. However, these same studies identified metabolic and vascular donor abnormalities. There are a few retrospective studies comparing donors with controls. Each has limitations in selection of the control group, statistical analyses, and/or length of follow-up. One such study reported increased donor mortality; 2 reported a small increase in absolute risk of ESKD. Risk factors for donor ESKD are similar to those in the general population. Postdonation pregnancies are also associated with increased risk of hypertension and preeclampsia. There is a critical need for long-term follow-up studies comparing donors with controls from the same era, geographic area, and socioeconomic status who are healthy, with normal renal function on the date matching the date of donation, and are matched on demographic characteristics with the donors. These data are needed to optimize donor candidate counseling and informed consent.

The Living Kidney Donor Safety Study: Protocol of a Prospective Cohort Study

Background

Living kidney donation is considered generally safe in healthy individuals; however, there is a need to better understand the long-term effects of donation on blood pressure and kidney function.

Objectives

To determine the risk of hypertension in healthy, normotensive adults who donate a kidney compared with healthy, normotensive non-donors with similar indicators of baseline health. We will also compare the 2 groups on the rate of decline in kidney function, the risk of albuminuria, and changes in health-related quality of life.

Design Participants and Setting

Prospective cohort study of 1042 living kidney donors recruited before surgery from 17 transplant centers (12 in Canada and 5 in Australia) between 2004 and 2014. Non-donor participants (n = 396) included relatives or friends of the donor, or donor candidates who were ineligible to donate due to blood group or cross-match incompatibility. Follow-up will continue until 2021, and the main analysis will be performed in 2022. The anticipated median (25th, 75th percentile, maximum) follow-up time after donation is 7 years (6, 8, 15).

Measurements

Donors and non-donors completed the same schedule of measurements at baseline and follow-up (non-donors were assigned a simulated nephrectomy date). Annual measurements were obtained for blood pressure, estimated glomerular filtration rate (eGFR), albuminuria, patient-reported health-related quality of life, and general health.

Outcomes

Incident hypertension (a systolic/diastolic blood pressure ≥ 140/90 mm Hg or receipt of anti-hypertensive medication) will be adjudicated by a physician blinded to the participant's donation status. We will assess the rate of change in eGFR starting from 12 months after the nephrectomy date and the proportion who develop an albumin-to-creatinine ratio ≥3 mg/mmol (≥30 mg/g) in follow-up. Health-related quality of life will be assessed using the 36-item RAND health survey and the Beck Anxiety and Depression inventories.

Limitations

Donation-attributable hypertension may not manifest until decades after donation.

Conclusion

This prospective cohort study will estimate the attributable risk of hypertension and other health outcomes after living kidney donation.

Pre-kidney Donation Pregnancy Complications and Long-term Outcomes

BACKGROUND

Hypertension and diabetes are contraindications for living kidney donation in young candidates. However, little is known about the long-term outcomes of women who had these pregnancy-related complications and subsequently became donors. In the general population, gestational hypertension (GHtn), preeclampsia/eclampsia, and gestational diabetes (GDM) are associated with long-term risks.

METHODS

Donors with the specified predonation complication were matched to contemporary control donors with pregnancies without the complication using nearest neighbor propensity score matching. Propensity scores were estimated using logistic regression with covariates for gravidity, blood pressure, glucose, body mass index, age, and creatinine at donation, donation year, race, relationship with recipient, and family history of disease. Long-term incidence of hypertension, diabetes, cardiovascular disease, and reduced renal function (estimated glomerular filtration rate [eGFR] <30, eGFR <45 mL/min/1.73 m 2 ) were compared between groups using proportional hazards models.

RESULTS

Of 1862 donors with predonation pregnancies, 48 had preeclampsia/eclampsia, 49 had GHtn without preeclampsia, and 43 had GDM. Donors had a long interval between first pregnancy and donation (median, 18.5 y; interquartile range, 10.6-27.5) and a long postdonation follow-up time (median, 18.0; interquartile range, 9.2-27.7 y). GHtn was associated with the development of hypertension (hazard ratio, 1.89; 95% confidence interval, 1.26-2.83); GDM was associated with diabetes (hazard ratio, 3.04; 95% confidence interval, 1.33-6.99). Pregnancy complications were not associated with eGFR <30 or eGFR <45 mL/min/1.73 m 2 .

CONCLUSIONS

Our data suggest that women with predonation pregnancy-related complications have long-term risks even with a normal donor evaluation. Donor candidates with a history of pregnancy-related complications should be counseled about these risks.

Assessing Renal Function for Kidney Donation. How Low Is Too Low?

Kidney transplantation (KT) is the treatment of choice for patients with end-stage kidney disease (ESKD) with decreased morbi-mortality, improved life quality, and reduced cost. However, the shortage of organs from deceased donors led to an increase in KT from living donors. Some stipulate that living donors have a higher risk of ESKD after donation compared with healthy non-donors. The reason for this is not clear. It is possible that ESKD is due to the nephrectomy-related reduction in glomerular filtration rate (GFR), followed by an age-related decline that may be more rapid in related donors. It is essential to assess donors properly to avoid rejecting suitable ones and not accepting those with a higher risk of ESKD. GFR is a central aspect of the evaluation of potential donors since there is an association between low GFR and ESKD. The methods for assessing GFR are in continuous debate, and the kidney function thresholds for accepting a donor may vary according to the guidelines. While direct measurements of GFR (mGFR) provide the most accurate evaluation of kidney function, guidelines do not systematically use this measurement as a reference. Also, some studies have shown that the GFR decreases with age and may vary with gender and race, therefore, the lower limit of GFR in patients eligible to donate may vary based on these demographic factors. Finally, it is known that CrCl overestimates mGFR while eGFR underestimates it, therefore, another way to have a reliable GFR could be the combination of two measurement methods.

Hypertension and renal outcomes in normotensive kidney donors with multiple renal arteries

Having multiple renal arteries (MRA) has been linked to hypertension development. Whether kidney donors who are left with MRA in the nondonated kidney incur a higher risk of hypertension has not been studied. We compared the development of hypertension, reduced estimated glomerular filtration rate (eGFR), cardiovascular disease, and mortality in 2624 normotensive kidney donors with MRA in the nondonated kidney and to 2624 propensity score matched normotensive donor controls with a single renal artery. In total, 35% of donors had MRA. Donors with MRA were less likely to have undergone a left nephrectomy (51% vs. 83%). Postdonation hypertension was associated with age, male gender, non-White ethnicity, obesity, and family history of hypertension. Having MRA was not associated with risk of hypertension; aHR 0.92 (95% CI 0.82-1.03), P = 0.16. After 17 ± 11 years from donation, a similar proportion of donors with and without MRA developed cardiovascular disease, proteinuria and eGFR <30, <45 and <60 mL/min/1.73 m² and the multivariable risks of developing these outcomes were similar in the two groups. Our study did not show increased risk for hypertension, reduced eGFR, proteinuria or cardiovascular disease in donors with MRA in the remaining kidney and without hypertension at donation.

Risk of kidney disease after living kidney donation

Living donor kidney transplantation benefits the recipient. However, kidney failure can occur in a small fraction of donors — the risk is not uniform but varies according to donor characteristics. Studies to date have failed to match on important factors, such as era, environment or family history. Long-term studies with well-matched healthy controls are therefore needed.

Long-term kidney function and survival in recipients of allografts from living kidney donors with hypertension: a national cohort study

Allografts from living kidney donors with hypertension may carry subclinical kidney disease from the donor to the recipient and, thus, lead to adverse recipient outcomes. We examined eGFR trajectories and all-cause allograft failure in recipients from donors with versus without hypertension, using mixed-linear and Cox regression models stratified by donor age. We studied a US cohort from 1/1/2005 to 6/30/2017; 49 990 recipients of allografts from younger (<50 years old) donors including 597 with donor hypertension and 21 130 recipients of allografts from older (≥50 years old) donors including 1441 with donor hypertension. Donor hypertension was defined as documented predonation use of antihypertensive therapy. Among recipients from younger donors with versus without hypertension, the annual eGFR decline was -1.03 versus -0.53 ml/min/m² (P = 0.002); 13-year allograft survival was 49.7% vs. 59.0% (adjusted allograft failure hazard ratio [aHR] 1.23; 95% CI 1.05-1.43; P = 0.009). Among recipients from older donors with versus without hypertension, the annual eGFR decline was -0.67 versus -0.66 ml/min/m² (P = 0.9); 13-year allograft survival was 48.6% versus 52.6% (aHR 1.05; 95% CI 0.94-1.17; P = 0.4). In secondary analyses, our inferences remained similar for risk of death-censored allograft failure and mortality. Hypertension in younger, but not older, living kidney donors is associated with worse recipient outcomes.

Outcomes of kidney donors with pre- and post-donation kidney stones

Roughly 25% of US transplant centers exclude donor candidates with kidney stones fearing future obstructive consequences and the possible association between stones and CKD. We compared the development of hypertension, proteinuria, and reduced eGFR in 227 kidney donors with kidney stones to 908 propensity score-matched donor controls without kidney stones using data from The Renal and Lung Donor Evaluation (RELIVE) Study which studied intermediate and long-term outcomes of 8922 donors who donated between 1963 and 2007. 200 donors had kidney stones prior to donation, 21 had post-donation stones, and 6 had pre- and post-donation stones. Donors with stones were older, more likely to be Caucasian, less likely to be related to the recipient and had a higher fasting glucose. After 16.5 ± 10.9 years (range 0-44 years) from donation to study close, no ESKD occurred in donors with stones. The multivariable risks of hypertension, proteinuria, and reduced GFR were similar in donors with and without kidney stones. We could not demonstrate an association between stones and adverse renal outcomes in kidney donors, and the occurrence of post-donation stones was distinctly rare. These data may provide a rationale for possibly a wider acceptance of donor candidates with low kidney stones burden.

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.

The present and future of transplant organ shortage: some potential remedies

Transplantation remains the modality of choice for patients with end stage renal disease (ESRD). However, while there has been a steady rise in the number of patients with ESRD the supply of donors (combine living and deceased) has fallen far behind the need, resulting in an increasing number of qualified patients remaining on the wait-list, and thousands being removed from the list every year because of death or becoming too sick for transplantation. This has also fed to transplant tourism around the world. Several countries have implemented a variety of policies to overcome their organ shortage that are presented in this article. There is an urgent need for developing policies geared to the cultural norms of different societies and universally accepted ethical principles to remedy this public health issue.

Kidney donor outcomes ≥ 50 years after donation

Many living kidney donors (LDs) are young at donation; yet there are little data on long-term LD follow-up. We report on 66 LDs who donated ≥50 years ago: 22 (33.3%) are still alive (current age, 78.5 ± 7.25 years); 39 (59%) died (mean age at death, 74.2 ± 12.3 years); and 5 are lost to follow-up (mean age at last contact, 68.7 ± 4.6 years). Those who died were older at donation (P < .001). Causes of death included 12 (30.8% of deaths) cardiovascular diseases, 9 (23.0%) respiratory failures, 5 (12.8%) malignancies and 4 (10.3%) infections, and 9 (23%) were unknown or miscellaneous. Forty-nine living donors (74%) developed hypertension at a mean age of 59.9 ± 14.0 years; 12 (18%) developed diabetes at a mean age of 62 ± 19.4 years; and 11 (16.7%) developed proteinuria at a mean age of 60.6 ± 18.2 years-each at a similar incidence as seen in the age-matched general population. At last follow-up, the eGFR by CKD-EPI (mean ± SD) for donors currently alive was 60.2 ± 13.4 mL/min/1.73 m² ; for those that died, 54.0 ± 21.5 mL/min/1.73 m² ; for those lost to follow-up, 55.6 ± 7.5 mL/min/1.73 m² . ESRD developed in 2 (3.3%). SF-36 quality of life health survey scores (n = 21) were similar to the age-matched general population.

Hypertension after kidney donation: Incidence, predictors, and correlates

Incidence of postdonation hypertension, risk factors associated with its development, and impact of type of treatment received on renal outcomes were determined in 3700 kidney donors. Using Cox proportional hazard model, adjusted hazard ratios (HRs) for cardiovascular disease (CVD); estimated glomerular filtration rate (eGFR) <60, <45, <30 mL/min/1.73m2 ; end stage renal disease (ESRD); and death in hypertensive donors were determined. After a mean (standard deviation [SD]) of 16.6 (11.9) years of follow-up, 1126 (26.8%) donors developed hypertension and 894 with known antihypertensive medications. Hypertension developed in 4%, 10%, and 51% at 5, 10, and 40 years, respectively, and was associated with proteinuria, eGFR < 30, 45, and 60 mL/min/1.73m2 , CVD, and death. Blood pressure was <140/90 mm Hg at last follow-up in 75% of hypertensive donors. Use of angiotensin-converting enzyme inhibitors or angiotensin receptor blockers (compared to other antihypertensive agents) was associated with a lower risk for eGFR <45 mL/min/1.73m², HR 0.64 (95% confidence interval [CI] 0.45-0.9), P = .01, and also less ESRD; HR 0.03 (95% CI 0.001-0.20), P = .004. In this predominantly Caucasian cohort, hypertension is common after donation, well controlled in most donors, and factors associated with its development are similar to those in the general population.

Causes and timing of end-stage renal disease after living kidney donation

End-stage renal disease (ESRD) is a risk after kidney donation. We sought, in a large cohort of kidney donors, to determine the causes of donor ESRD, the interval from donation to ESRD, the role of the donor/recipient relationship, and the trajectory of the estimated GFR (eGFR) from donation to ESRD. From 1/1/1963 thru 12/31/2015, 4030 individuals underwent living donor nephrectomy at our center, as well as ascertainment of ESRD status. Of these, 39 developed ESRD (mean age ± standard deviation [SD] at ESRD, 62.4 ± 14.1 years; mean interval between donation and ESRD, 27.1 ± 9.8 years). Donors developing ESRD were more likely to be male, as well as smokers, and younger at donation, and to have donated to a first-degree relative. Of donors with a known cause of ESRD (n = 25), 48% was due to diabetes and/or hypertension; only 2 from a disease that would have affected 1 kidney (cancer). Of those 25 with an ascertainable ESRD cause, 4 shared a similar etiology of ESRD with their recipient. Almost universally, thechange of eGFR over time was stable, until new-onset disease (kidney or systemic). Knowledge of factors contributing to ESRD after living kidney donation can improve donor selection and counseling, as well as long-term postdonation care.

Renal Consequences of Diabetes After Kidney Donation

Whether diabetes after kidney donation is associated with an accelerated GFR decay in the remaining kidney has not been studied. We determined the incidence of diabetes in kidney donors, and compared GFR change over time in diabetic to nondiabetic donors, in addition to the effect of diabetes mellitus (DM) on the development of proteinuria, hypertension, and end-stage renal disease (ESRD). Of the 4014 donors, 309 (7.7%) developed diabetes at a median age of 56.0 years and after a median of 18 years after donation. The difference in annual estimated GFR (eGFR) change between diabetic and nondiabetic donors in the 7 years before the development of DM was -0.08 mL/min/year; p = 0.51. After DM development, the difference was -1.10 mL/min/year for diabetic donors with hypertension and proteinuria, p < 0.001; -0.19 for diabetic donors with hypertension but no proteinuria, p = 0.29; -0.75 mL/min/year for diabetic donors with proteinuria but no hypertension, p = 0.19; and -0.09 mL/min/year for diabetic donors without proteinuria or hypertension, p = 0.63. When DM was considered as a time-dependent covariate, it was associated with the development of proteinuria (hazard ratio [HR] 2.65, 95% confidence interval [CI] 1.89-3.70; p < 0.001) and hypertension (HR 2.19, 95% CI 1.74-2.75; p < 0.001). It was not, however, associated with ESRD. eGFR decline after DM development exceeds that of nondiabetic donors only in diabetic donors with concomitant proteinuria and hypertension.