Reassessing medical risk in living kidney donors

Consequences of low estimated glomerular filtration rate either before or early after kidney donation

In the general population, decreases in glomerular filtration rate (GFR) are associated with subsequent development of chronic kidney disease (CKD), cardiovascular disease (CVD), and death. It is unknown if low estimated GFR (eGFR) before or early after kidney donation was also associated with these risks. One thousand six hundred ninety-nine living donors who had both predonation and early (4-10 weeks) postdonation eGFR were included. We studied the relationships between eGFR, age at donation, and the time to sustained eGFR<45 (CKD stage 3b) and <30 mL/min/1.73m2 (CKD stage 4), hypertension, diabetes mellitus (DM), CVD, and death. Median follow-up was 12 (interquartile range, 6-21) years. Twenty-year event rates were 5.8% eGFR<45 mL/min/1.73m2; 1.2% eGFR<30 mL/min/1.73m2; 29.0% hypertension; 7.8% DM; 8.0% CVD; and 5.2% death. The median time to eGFR<45 mL/min/1.73m2 (N = 79) was 17 years, and eGFR<30 mL/min/1.73m2 (N = 22) was 25 years. Both low predonation and early postdonation eGFR were associated with eGFR<45 mL/min/1.73m2 (P < .0001) and eGFR<30 mL/min/1.73m2 (P < .006); however, the primary driver of risk for all ages was low postdonation (rather than predonation) eGFR. Predonation and postdonation eGFR were not associated with hypertension, DM, CVD, or death. Low predonation and early postdonation eGFR are risk factors for developing eGFR<45 mL/min/1.73m2 (CKD stage 3b) and <30 mL/min/1.73m2 (CKD stage 4), but not CVD, hypertension, DM, or death.

Implementation of a culturally competent APOL1 genetic testing programme into living donor evaluation: A two-site, non-randomised, pre-post trial design

INTRODUCTION

While living donor (LD) kidney transplantation is the optimal treatment for patients with kidney failure, LDs assume a higher risk of future kidney failure themselves. LDs of African ancestry have an even greater risk of kidney failure post-donation than White LDs. Because evidence suggests that Apolipoprotein L1 (APOL1) risk variants contribute to this greater risk, transplant nephrologists are increasingly using APOL1 genetic testing to evaluate LD candidates of African ancestry. However, nephrologists do not consistently perform genetic counselling with LD candidates about APOL1 due to a lack of knowledge and skill in counselling. Without proper counselling, APOL1 testing will magnify LD candidates' decisional conflict about donating, jeopardising their informed consent. Given cultural concerns about genetic testing among people of African ancestry, protecting LD candidates' safety is essential to improve informed decisions about donating. Clinical 'chatbots', mobile apps that provide genetic information to patients, can improve informed treatment decisions. No chatbot on APOL1 is available and no nephrologist training programmes are available to provide culturally competent counselling to LDs about APOL1. Given the shortage of genetic counsellors, increasing nephrologists' genetic literacy is critical to integrating genetic testing into practice.

METHODS AND ANALYSIS

Using a non-randomised, pre-post trial design in two transplant centres (Chicago, IL, and Washington, DC), we will evaluate the effectiveness of culturally competent APOL1 testing, chatbot and counselling on LD candidates' decisional conflict about donating, preparedness for decision-making, willingness to donate and satisfaction with informed consent and longitudinally evaluate the implementation of this intervention into clinical practice using the Reach, Effectiveness, Adoption, Implementation and Maintenance framework.

ETHICS AND DISSEMINATION

This study will create a model for APOL1 testing of LDs of African ancestry, which can be implemented nationally via implementation science approaches. APOL1 will serve as a model for integrating culturally competent genetic testing into transplant and other practices to improve informed consent. This study involves human participants and was approved by Northwestern University IRB (STU00214038). Participants gave informed consent to participate in the study before taking part.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT04910867. Registered 8 May 2021, https://register.

CLINICALTRIALS

gov/prs/app/action/SelectProtocol?sid=S000AWZ6&selectaction=Edit&uid=U0001PPF&ts=7&cx=-8jv7m2 ClinicalTrials.gov Identifier: NCT04999436. Registered 5 November 2021, https://register.

CLINICALTRIALS

gov/prs/app/action/SelectProtocol?sid=S000AYWW&selectaction=Edit&uid=U0001PPF&ts=11&cx=9tny7v.

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.

Long-term compensation of renal function after donor nephrectomy

Background

Living donors are the major source of kidneys in countries with a shortage of deceased donors. Kidney donation after careful donor selection is generally accepted as a safe procedure, but the physiologic consequences after donor nephrectomy are not fully verified. In this study we retrospectively reviewed the renal function of the residual kidney in living donors.

Methods

Post-nephrectomy laboratory data of 1,175 living donors (60.7%) from 1,933 living donors who received uninephrectomy from January 1999 to December 2017 at Yonsei University, Severance Hospital, Korea were retrospectively collected. Post-nephrectomy renal function was monitored by the relative ratio of estimated glomerular filtration rate (e-GFR; pre-nephrectomy e-GFR ratio vs. post-nephrectomy e-GFR) that was calculated by the Modification of Diet in Renal Disease formula.

Results

During 36.3±37.6 months of mean follow-up, two cases (0.17%, 2/1,175) of renal failure developed. The mean e-GFR decreased to 64.3±14.2 mL/min/1.73 m2 immediately after nephrectomy from 99.2±19.9 mL/min/1.73 m2 of the pre-nephrectomy e-GFR. Early decrement of e-GFR was prominent in male and obese donors (body mass index >25 kg/m2, P<0.05). The e-GFR ratio increased according to post-nephrectomy duration, and the mean increment degree of e-GFR ratio after nephrectomy calculated by linear regression analysis was 1.94% per year. Unlike the early decrement of e-GFR ratio after nephrectomy, donor factors such as degree of obesity and donor sex did not affect the late increment of e-GFR ratio after nephrectomy (P>0.05).

Conclusions

Our data showed that long-term compensation of the renal function after nephrectomy occurs independently of preoperative donor characteristics.

Identifying Outcomes that Are Important to Living Kidney Donors: A Nominal Group Technique Study

BACKGROUND AND OBJECTIVES

Living kidney donor candidates accept a range of risks and benefits when they decide to proceed with nephrectomy. Informed consent around this decision assumes they receive reliable data about outcomes they regard as critical to their decision making. We identified the outcomes most important to living kidney donors and described the reasons for their choices.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Previous donors were purposively sampled from three transplant units in Australia (Sydney and Melbourne) and Canada (Vancouver). In focus groups using the nominal group technique, participants identified outcomes of donation, ranked them in order of importance, and discussed the reasons for their preferences. An importance score was calculated for each outcome. Qualitative data were analyzed thematically.

RESULTS

Across 14 groups, 123 donors aged 27-78 years identified 35 outcomes. Across all participants, the ten highest ranked outcomes were kidney function (importance=0.40, scale 0-1), time to recovery (0.27), surgical complications (0.24), effect on family (0.22), donor-recipient relationship (0.21), life satisfaction (0.18), lifestyle restrictions (0.18), kidney failure (0.14), mortality (0.13), and acute pain/discomfort (0.12). Kidney function and kidney failure were more important to Canadian participants, compared with Australian donors. The themes identified included worthwhile sacrifice, insignificance of risks and harms, confidence and empowerment, unfulfilled expectations, and heightened susceptibility.

CONCLUSIONS

Living kidney donors prioritized a range of outcomes, with the most important being kidney health and the surgical, lifestyle, functional, and psychosocial effects of donation. Donors also valued improvements to their family life and donor-recipient relationship. There were clear regional differences in the rankings.

Risk of ESRD in prior living kidney donors

We studied End-Stage Renal Disease (ESRD) in living kidney donors (LKDs) who donated in the United States between 1994 and 2016 (n = 123 526), using Organ Procurement and Transplantation Network and Centers for Medicare and Medicaid Services data. Two hundred eighteen LKDs developed ESRD, with a median of 11.1 years between donation and ESRD. Absolute 20-year risk was low but not uniform, with risk associated with race, age, and sex and increasing exponentially over time. LKDs had increased risk of ESRD if they were male (adjusted hazard ratio [aHR]: 1.75, 95% confidence interval [95%CI]: 1.33-2.31), had higher BMI (aHR: 1.34 per 5 kg/m² , 95%CI: 1.10-1.64) or lower estimated GFR (aHR: 0.89 per 10 mL/min, 95% CI: 0.80-0.99), were first-degree relatives of the recipient (parent: [aHR: 2.01, 95% CI: 1.26-3.21]; full sibling [aHR: 1.87, 95%CI: 1.23-2.84]; identical twin [aHR: 19.79, 95%CI: 7.65-51.24]), or lived in lower socioeconomic status neighborhoods at donation (aHR: 0.87 per $10k increase; 95%CI: 0.77-0.99). We found a significant interaction between donation age and race, with higher risk at older ages for white LKDs (aHR: 1.26 per decade, 95%CI: 1.04-1.54), but higher risk at younger ages for black LKDs (aHR: 0.75 per decade, 95%CI: 0.57-0.99). These findings further inform risk assessment of potential LKDs.

Organ Vouchers and Barter Markets: Saving Lives, Reducing Suffering, and Trading in Human Organs

The essays in this issue of The Journal of Medicine and Philosophy explore an innovative voucher program for encouraging kidney donation. Discussions cluster around a number of central moral and political/theoretical themes: (1) What are the direct and indirect health care costs and benefits of such a voucher system in human organs? (2) Do vouchers lead to more effective and efficient organ procurement and allocation or contribute to greater inequalities and inefficiencies in the transplantation system? (3) Do vouchers contribute to the inappropriate commodification of human body parts? (4) Is there a significant moral difference between such a voucher system and a market in human organs for transplantation? This paper argues that while kidney vouchers constitute a step in the right direction, fuller utilization of market-based incentives, including, but not limited to, barter exchanges (e.g., organ exchanges, organ chains, and organ vouchers), would save more lives and further reduce human suffering.

Swaps and Chains and Vouchers, Oh My!: Evaluating How Saving More Lives Impacts the Equitable Allocation of Live Donor Kidneys

Live kidney donation involves a delicate balance between saving the most lives possible and maintaining a transplant system that is fair to the many thousands of patients on the transplant waiting list. Federal law and regulations require that kidney allocation be equitable, but the pressure to save patients subject to ever-lengthening waiting times for a transplant has been swinging the balance toward optimizing utility at the expense of justice. This article traces the progression of innovations created to make optimum use of a patient's own live donors. It starts with the simplest - direct donation by family members - and ends with voucher donations, a very recent and unique innovation because the donor can donate 20 or more years before the intended recipient is expected to need a kidney. In return for the donation, the intended recipient receives a voucher that can be redeemed for a live kidney when it is needed. Other innovations that are discussed include kidney exchanges and list paired donation, which are used to facilitate donor swaps when donor/recipient pairs have incompatible blood types. The discussion of each new innovation shows how the equity issues build on each other and how, with each new innovation, it becomes progressively harder to find an acceptable balance between utility and justice. The article culminates with an analysis of two recent allocation methods that have the potential to save many additional lives, but also affirmatively harm some patients on the deceased donor waiting list by increasing their waiting time for a life-saving kidney. The article concludes that saving additional lives does not justify harming patients on the waiting list unless that harm can be minimized. It also proposes solutions to minimize the harm so these new innovations can equitably perform their intended function of stimulating additional transplants and extending the lives of many transplant patients.

Neutrophil Gelatinase-Associated Lipocalin, Fibroblast Growth Factor 23, and Soluble Klotho in Long-Term Kidney Donors

Background

The best treatment for end-stage renal disease (ESRD) is kidney transplantation. Twenty-seven percent of transplantations in Norway are from living donors. Recent studies have shown an increased risk of ESRD and increased mortality in donors. The aim of this study was to determine if the levels of the new biomarkers neutrophil gelatinase-associated lipocalin (NGAL), soluble Klotho (sKlotho), and fibroblast growth factor 23 (FGF23) are changed in kidney donors with normal kidney function defined as an estimated glomerular filtration rate (eGFR) >60 ml/min/1.73 m² compared to patients with chronic kidney disease (CKD) stages 3-5 and healthy controls.

Methods

This is a cross-sectional, observational, single-center study including 35 kidney donors with an eGFR ≥60 ml/min/1.73 m² 5 years after donation, 22 patients with CKD stage 3 (eGFR 30-59 ml/min/1.73 m²), 18 patients with CKD stage 4 (eGFR 15-29 ml/min/1.73 m²), 20 patients with CKD stage 5 (eGFR <15 ml/min/1.73 m²), and 35 controls comparing levels of biomarkers in long-term kidney donors with those in CKD patients and healthy controls.

Results

The level of log NGAL was significantly higher in donors than in healthy controls (2.02 ± 0.10 vs. 1.89 ± 0.10 ng/ml; p < 0.001), and the level increased with declining kidney function. The log FGF23 level was nonsignificantly higher in donors than in controls, but it significantly increased with declining kidney function. The log sKlotho levels were significantly lower in patients with CKD stages 4 and 5 than in controls, but no difference was revealed between controls and donors.

Conclusion

Kidney donors have significantly higher levels of NGAL than healthy controls after a median of 15 years (range 5-38). NGAL could be a valuable diagnostic marker in the future. FGF23 and sKlotho were not significantly different between donors and controls.

Living kidney donation does not adversely affect serum calcification propensity and markers of vascular stiffness

Living kidney donors (LKDs) experience a decline in glomerular filtration rate (GFR) after donation. Calcification propensity (T50 ) can be determined by a blood test predicting all-cause mortality in patients with chronic kidney disease. We studied the impact of kidney donation on T50 and markers of arterial stiffness. We analyzed T50 prospectively before and 1 year after kidney donation in 21 LKDs along with fetuin-A, mineral metabolism markers, kidney length, pulse wave velocity (PWV), augmentation index (AI), and renal resistive index (RRI) as markers of arterial stiffness. We studied the impact of kidney donation on these parameters. LKDs were 54 ± 10 years old and had a GFR of 101 ± 18 ml/min/1.73 m(2) before donation, decreasing to 67 ± 8 ml/min/1.73 m(2) after donation (P < 0.001). Despite this, T50 improved after donation (290 ± 53 to 312 ± 38 min, P = 0.049). This change was inversely related to plasma phosphate (P = 0.03), which declined after donation (P = 0.002). Fetuin-A levels increased after donation (P = 0.01). Upon donation, the length of the remaining kidney increased (P < 0.001) while PWV, AI, and RRI remained unchanged. Calcification propensity was not adversely affected by kidney donation. This indicates that T50 is independent from GFR in LKDs and that kidney donation does neither worsen calcification propensity nor markers of vascular stiffness at 1 year.