Live kidney donation: are concerns about long-term safety justified?-A methodological review

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.

Donor‐reported barriers to living kidney donor follow‐up

BACKGROUND

Despite regulations mandating follow-up laboratory testing for living kidney donors, less than half of transplant centers are in compliance. We sought to understand barriers to follow-up testing from the donors' perspective.

METHODS

We surveyed our center's living kidney donors. Binary logistic regression was used to assess factors associated with follow-up testing completion.

RESULTS

Of 185 living kidney donors, 110 (59.4%) participated. Among them, 82 (74.5%) completed 6-month laboratory testing, 76 (69.1%) completed 12-month testing, 68 (61.8%) completed both, and 21 (19.0%) completed neither. Six-month testing completion was strongly associated with 12-month testing completion (OR 9.74, 95%CI: 2.23-42.50; p = .002). Those who disagreed with the statements, "Getting labs checked wasn't a priority for me," (OR for completing 6-month testing: 15.05, 95%CI: 3.70-61.18; p < .001; OR for completing 12-month testing: 5.85, 95%CI: 1.94-17.63; p = .002); and, "I forgot to get labs drawn [until I was reminded]" (OR for completing 6-month testing: 6.93, 95%CI: 1.59-30.08; p = .01; OR for completing 12-month testing: 6.55, 95%CI: 1.98-21.63; p = .002) were more likely to complete testing.

CONCLUSIONS

To our knowledge, this is the only study providing perspective on donor insights regarding the need for follow-up testing post donation. Interventions to influence living donor attitudes toward follow-up testing may improve follow-up.

Outcomes of Living Kidney Donor Candidate Evaluations in the Living Donor Collective Pilot Registry

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Background.

Gaps in our knowledge of long-term outcomes affect decision making for potential living kidney donors.

Methods.

The Scientific Registry of Transplant Recipients was asked to determine the feasibility of a candidate registry.

Results.

Ten living kidney donor programs evaluated 2107 consecutive kidney donor candidates; 2099 of 2107 (99.6%) completed evaluations, 1578 of 2099 (75.2%) had a decision, and 790 of 1578 (50.1%) were approved to donate as of March 12, 2020. By logistic regression, candidates most likely to be approved were married or had attended college or technical school; those least likely to be approved had ≥1 of the following characteristics: Black race, history of cigarette smoking, and higher blood pressure, higher triglycerides, or higher urine albumin-to-creatinine ratios. Reasons for 617 candidates not being approved included medical issues other than chronic kidney disease risk (25.3%), chronic kidney disease risk (18.5%), candidate withdrawal (15.2%), recipient reason (13.6%), anatomical risk to the recipient (10.3%), noneconomic psychosocial (10.3%), economic (0.5%), and other reasons (6.4%).

Conclusions.

These results suggest that a comprehensive living donor registry is both feasible and necessary to assess long-term outcomes that may inform decision making for future living donor candidates. There may be socioeconomic barriers to donation that require more granular identification so that active measures can address inequities. Some candidates who did not donate may be suitable controls for discerning the appropriateness of acceptance decisions and the long-term outcomes attributable to donation. We anticipate that these issues will be better identified with modifications to the data collection and expansion of the registry to all centers over the next several years.

How Does the Remaining Single Kidney Cope After Contralateral Nephrectomy of the Kidney Donor? A Single-Center Cohort Study

Introduction

Immediately after kidney donation, the remaining kidney will undergo hyperfiltration and work at a higher level to compensate for the other kidney's loss. It is estimated that 70% of the baseline renal function before the donation is recovered post-donation. However, factors that determine the post-donation renal compensation are not well understood.

Methods

We conducted a retrospective study of 190 consecutive kidney donors who completed a one-year follow-up in order to predict the factors affecting the function of the remaining kidney post-contralateral nephrectomy.

Results

We enrolled 190 living kidney donors who had completed at least one year of follow-up after nephrectomy. Among the participants, 149 (78.4%) were males and 41 (21.6%) were females. The mean age of the participants was 31.33 ±7.9 years and the mean body mass index (BMI) was 25.6 ±3.9 kg/m². Before kidney donation, the mean estimated glomerular filtration rate (eGFR) and serum creatinine were 114.31 ±15.94 ml/min/1.73 m² and 71.60 ±10.62 mmol/min, respectively. At the one-year follow-up, the mean eGFR was 77.97 ±14.44 ml/min/1.73 m² and serum creatinine was 100.84 ±20.15 mmol/min. The female gender [odds ratio (OR): 20.6, 95% CI: 3.9-107.7, p: <0.001] and having a higher baseline eGFR (OR: 8.8, 95% CI: 1.6-45.8, p = 0.01) were found to be significant predictors of having a better eGFR at one year post-nephrectomy.

Conclusions

Female gender and pre-donation low serum creatinine and high eGFR were the significant predictors of better kidney function at one year post-contralateral nephrectomy. However, further studies with longer follow-up durations are needed to better assess the factors that could predict renal compensation and the renal compensation rate's suitability as a prognostic measure for long-term renal outcomes.

Long-term prognosis after kidney donation: a propensity score matched comparison of living donors and non-donors from two population cohorts

Background

Live donor nephrectomy is a safe procedure. However, long-term donor prognosis is debated, necessitating high-quality studies.

Methods

A follow-up study of 761 living kidney donors was conducted, who visited the outpatient clinic and were propensity score matched and compared to 1522 non-donors from population-based cohort studies. Primary outcome was kidney function. Secondary outcomes were BMI (kg/m²), incidences of hypertension, diabetes, cardiovascular events, cardiovascular and overall mortality, and quality of life.

Results

Median follow-up after donation was 8.0 years. Donors had an increase in serum creatinine of 26 μmol/l (95% CI 24–28), a decrease in eGFR of 27 ml/min/1.73 m² (95% CI − 29 to − 26), and an eGFR decline of 32% (95% CI 30–33) as compared to non-donors. There was no difference in outcomes between the groups for ESRD, microalbuminuria, BMI, incidence of diabetes or cardiovascular events, and mortality. A lower risk of new-onset hypertension (OR 0.45, 95% CI 0.33–0.62) was found among donors. The EQ-5D health-related scores were higher among donors, whereas the SF-12 physical and mental component scores were lower.

Conclusion

Loss of kidney mass after live donation does not translate into negative long-term outcomes in terms of morbidity and mortality compared to non-donors.

Trial registration

Dutch Trial Register NTR3795.

Electronic supplementary material

The online version of this article (10.1007/s10654-020-00647-y) contains supplementary material, which is available to authorized users.

A prospective controlled study of metabolic and physiologic effects of kidney donation suggests that donors retain stable kidney function over the first nine years

While there have been numerous studies of living kidney donors, most have been retrospective without suitable controls and have yielded conflicting results. To clarify this we studied 205 living donor candidates and 203 controls having no medical conditions precluding donation. Before and at six months, one, two, three, six, and nine years after donation we measured iohexol glomerular filtration rate, clinic blood pressure, urine protein excretion and metabolic parameters reported to be affected by kidney function. We measured 24 hour ambulatory blood pressure at three, six, and nine years and at six and nine years blood pressure after treadmill exercise, carotid-femoral pulse wave velocity and arterial elasticity. Between six months and nine years, the mean (95% confidence interval) change in glomerular filtration rate was significantly different among 133 donors 0·02 (-0·16-0·20) mL/min/1·73m²/year versus -1·26 (-1·52--1·00) mL/min/1·73m²/year in 113 healthy controls. Blood pressure, urine protein, urine albumin, glucose, hemoglobin A1c, insulin, and lipoproteins were not different in controls versus donors; but parathyroid hormone, homocysteine and uric acid remained higher at nine years. At six and nine years carotid-femoral pulse wave velocity was not different, but the mean small artery elasticity was significantly lower in 141 donors 6·1 mL/mmHg x100, versus 113 controls 7·1 mL/mmHg x100, and 6·1 mL/mmHg x100 in 137 donors versus 7·6 mL/mmHg x100 in 112 controls at six and nine years, respectively [significant adjusted difference of 1·1 mL/mmHg x100]. Thus, donors remain healthy with stable kidney function for the first nine years, but differences in metabolic and vascular parameters could be harbingers of adverse outcomes requiring future interventions.

Psychological Aspects of Living Kidney Donation in Poland: Experience of One Center

BACKGROUND

Living kidney transplantation is the optimal treatment of end-stage renal disease. The benefits for recipients are obvious. The psychological consequences for living kidney donors in Poland are not known.

OBJECTIVE

The objective of the study was to evaluate the psychological aspects of living kidney donation in Poland.

PATIENTS AND METHODS

A total of 66 living donor open nephrectomies were performed in our institution between 1995 and 2005. The psychological aspects were assessed in 40 donors after nephrectomy. The study applied the Satisfaction With Life Scale (SWLS), the Situation Assessment Questionnaire, the Health Behaviors Survey, and our own questionnaire. The mean observation period was 65.6 months.

RESULTS

There was a trend toward better life satisfaction in living kidney donors compared to Polish adults. Donor life satisfaction was significantly lower when the recipient was dead than when the recipient was alive. Most donors perceived the kidney donation as a challenge in cognitive judgment. The mean score of the Health Behaviors Survey was not significantly different than in the general population in Poland. The mean pain score after donation was 3.2 in a 5-item scale (1 = severe pain, 5 = mild pain). The mean time of return to work was 3.5 months. No donors regretted their decisions about kidney donation.

CONCLUSION

Living kidney donation in Poland has a positive impact on donors' quality of life. Among living kidney donors, the sense of danger concerning the risk of donation depends on the degree of the relationship with the recipient.

Adaptive Personality Traits and Psychosocial Correlates among Living Kidney Donors

Since living kidney donors have repeatedly been shown to be mentally more healthy compared to the general population, they might also exhibit more adaptive personality characteristics. We investigated the personality traits of 315 living kidney donors (202 female and 113 male donors) on average 7.1 years after donation using the NEO-Five Factor Inventory, a frequently used personality inventory measuring the "big five" dimensions of personality (neuroticism, extraversion, openness, agreeableness, and conscientiousness). In addition, levels of depression, anxiety, and fatigue were assessed with the Patient Health Questionnaire-Depression Scale, GAD-7, and Multidimensional Fatigue Inventory. Kidney donors showed more adaptive personality traits with higher agreeableness and lower neuroticism scores compared to the German general population. This was even more pronounced in living kidney donors with a high motivation to donate again (non-regreters). Scores for depression, anxiety, and fatigue did not differ from general population values and were significantly correlated with most personality dimensions. The more adaptive personality characteristics of living kidney donors might either be a selection effect or the consequence of the experience of donation and improved health of the close relative. Regardless of the causal relationship, adaptive personality traits might positively influence both physical and psychosocial well-being of the donor. Longitudinal studies should investigate if living donation might lead to persistent adaptive changes in personality traits.

Five-year follow-up after live donor nephrectomy - cross-sectional and longitudinal analysis of a prospective cohort within the era of extended donor eligibility criteria

To establish the outcome of live kidney donors 5 years after donation, we investigated the risk for progressive renal function decline and quality of life (QoL). Data on estimated glomerular filtration rate (eGFR), creatinine, hypertension, QoL and survival were assessed in a prospective cohort of 190 donors, who donated between 2008 and 2010. Data were available for >90%. The mean age predonation was 52.8 ± 11.5 years, 30 donors having pre-existent hypertension. The mean follow-up was 5.1 ± 0.9 years. Eight donors had died due to non-donation-related causes. After 5 years, the mean eGFR was 60.2 (95% CI 58.7-62.7) ml/min/1.73 m² , with a median serum creatinine of 105.1 (95% CI 102.5-107.8) μmol/l. eGFR decreased to 33.6% and was longitudinally lower among men than women and declining with age (P < 0.001), without any association on QoL. Donors with pre-existent and new-onset hypertension demonstrated no progressive decline of renal function overtime compared to nonhypertensives. No donors were found with proteinuria, microalbuminuria or at risk for end-stage renal disease. After an initial decline postdonation, renal function remained unchanged overtime. Men and ageing seem to affect renal function overtime, while decreased renal function did not affect QoL. These data support further stimulation of living kidney donation programmes as seen from the perspective of donor safety.