Obesity and long-term mortality risk among living kidney donors

doi:10.1016/j.surg.2019.03.016

Surgery

Volume 166, Issue 2, August 2019, Pages 205-208

https://doi.org/10.1016/j.surg.2019.03.016 Get rights and content

Abstract

Background

Body mass index of living kidney donors has increased substantially. Determining candidacy for live kidney donation among obese individuals is challenging because many donation-related risks among this subgroup remain unquantified, including even basic postdonation mortality.

Methods

We used data from the Scientific Registry of Transplant Recipients linked to data from the Centers for Medicare and Medicaid Services to study long-term mortality risk associated with being obese at the time of kidney donation among 119,769 live kidney donors (1987–2013). Donors were followed for a maximum of 20 years (interquartile range 6.0–16.0). Cox proportional hazards estimated the risk of postdonation mortality by obesity status at donation. Multiple imputation accounted for missing obesity data.

Results

Obese (body mass index ≥ 30) living kidney donors were more likely male, African American, and had higher blood pressure. The estimated risk of mortality 20 years after donation was 304.3/10,000 for obese and 208.9/10,000 for nonobese living kidney donors. Adjusting for age, sex, race/ethnicity, blood pressure, baseline estimated glomerular filtration rate, relationship to recipient, smoking, and year of donation, obese living kidney donors had a 30% increased risk of long-term mortality compared with their nonobese counterparts (adjusted hazard ratio: 1.32, 95% CI: 1.09–1.60, P = .006). The impact of obesity on mortality risk did not differ significantly by sex, race or ethnicity, biologic relationship, baseline estimated glomerular filtration rate, or among donors who did and did not develop postdonation kidney failure.

Conclusion

These findings may help to inform selection criteria and discussions with obese persons considering living kidney donation.

Introduction

Since the year 2004, there has been a 13% decline in living kidney donation in the United States,¹ and this observed trend differs significantly from recent increases in living donation seen in other parts of the world, including the United Kingdom, Japan, the Netherlands, Mexico, and Australia.¹ The reasons for declining rates of living donation in the United States are likely multifactorial¹ but correspond with an increasingly unhealthy US general population2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 and questions surrounding donation-related health risks, particularly among living kidney donors with isolated medical abnormalities at the time of donation, such as obesity (body mass index [BMI] ≥ 30kg/m²).¹³

The prevalence of obesity in the United States has increased from 27.5% in 1999 to 36.5% in 2014,² and, along with the general population, the BMI of living kidney donors has also risen, with more than 25% of all contemporary living kidney donors with obesity at time of donation compared with fewer than 8% in the 1970s.¹⁴ As newer data emerge on donation-related health risks, the transplant community continues to debate the optimal acceptable BMI threshold for living donors. Guidelines have suggested that live donor candidates with BMI ≥ 35kg/m² should be discouraged from donating,¹⁵ and others have suggested that patients with BMI > 30kg/m² should reduce their weight before donation.¹⁶ Currently, the 2017 Kidney Disease Improving Global Outcomes clinical practice guidelines suggest that the decision to approve living donor candidates with BMI > 30kg/m² should be individualized based on patients’ demographic and health profiles in relation to the transplant program’s acceptable risk threshold.¹⁷

Within the general population, obesity is strongly associated with an increased risk for cardiovascular disease, diabetes, chronic kidney disease, end-stage renal disease (ESRD)3, 4, 5, 6, 7, 11, 18 and mortality.19, 20 Studies among obese living donors, however, have primarily focused on the risk of ESRD, demonstrating a 1.16-fold and a 1.86-fold higher ESRD risk among obese potential living donor candidates (adjusted hazard ratio [aHR]: 1.16; 95% CI: 1.04–1.29)²¹ and actual obese living kidney donors (aHR: 1.86; 95% CI: 1.05–3.30),²² respectively. The 2 major studies addressing mortality risk among living donors failed to risk-stratify by BMI23, 24 and therefore no study to date has specifically quantified the long-term mortality risks faced by obese donors.

Not surprisingly, tremendous variation in BMI thresholds for living donation exist across US transplant centers, highlighting persistent knowledge gaps in our current understanding of living-donor risks among obese donors and the need for continued focused research among this at-risk subgroup.²⁵ To improve our understanding of the risk of mortality in obese living kidney donors to enhance donor selection practices, we utilized a national registry to examine the association between BMI and postdonation risk of long-term mortality among living kidney donors, adjusting for potential confounders and exploring the presence of effect modification.

Section snippets

Methods

The study used data from the Scientific Registry of Transplant Recipients (SRTR). The SRTR data system includes data on all donors, waitlisted candidates, and transplant recipients in the United States, submitted by members of the Organ Procurement and Transplantation Network (OPTN). The Health Resources and Services Administration of the US Department of Health and Human Services provides the oversight to the activities of the OPTN and SRTR contractors. We included all adult kidney-only living

Results

We identified 119,769 living kidney donors from October 1, 1987, to June 30, 2013. Of these, 78,592 had BMI data reported at donation. Obese living donors were more often male (43.1% vs 39.2%) and African American (16.4% vs 11.1%). Predonation blood pressures were higher in obese living donors (mean systolic 124.4 mmHg vs 119.9 mmHg and mean diastolic 75.6 mmHg vs 72.9 mmHg) than in nonobese donors. Obese donors did not differ significantly from nonobese donors regarding age, baseline eGFR,

Discussion

In this national study of 119,769 living kidney donors, we calculated a postdonation long-term death rate at 20 years of 209/10,000 among nonobese donors and 304/10,000 for obese living donors. Although the absolute risk for postdonation mortality remains low, the magnitude of the mortality risk difference between these 2 donor groups is significant. After adjusting for age, ethnicity, gender, baseline eGFR, baseline blood pressure, smoking history, year of donation, and relationship to the

Acknowledgments

The interpretation and reporting of these data are the responsibility of the authors and in no way should be seen as an official policy of or interpretation by the National Institutes of Health, SRTR, OPTN, or the American Society of Transplantation.

Conflict of interest

The authors have indicated that they have no conflict of interest regarding the content of this article.

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Cited by (21)

Antiobesity pharmacotherapy to facilitate living kidney donation
2024, American Journal of Transplantation
Obesity is a chronic, relapsing disease that increases the risks of living kidney donation; at the same time, transplant centers have liberalized body mass index constraints for donors. With the increasing number of antiobesity medications available, the treatment of obesity with antiobesity medications may increase the pool of potential donors and enhance donor safety. Antiobesity medications are intended for long-term use given the chronic nature of obesity. Cessation of treatment can be expected to lead to weight regain and increase the risk of comorbidity rebound/development. In addition, antiobesity medications are meant to be used in conjunction with—rather than in replacement of—diet and physical activity optimization. Antiobesity medication management includes selecting medications that may ameliorate any coexisting medical conditions, avoiding those that are contraindicated in such conditions, and being sensitive to any out-of-pocket expenses that may be incurred by the potential donor. A number of questions remain regarding who will and should shoulder the costs of long-term obesity treatment for donors. In addition, future studies are needed to quantify the degree of weight loss and duration of weight loss maintenance needed to normalize the risk of adverse kidney outcomes relative to comparable nondonors and lower-weight donors.
Recommendations for living donor kidney transplantation
2022, Nefrologia
Citation Excerpt :
Few studies have analysed the possible implications of obesity for donor mortality over the long-term. Recently, and although the level of absolute risk was low, an increase in mortality over the long-term has been described in donors with a BMI ≥30 Kg/m2 271. This datum underlines the need to insist on the importance of sufficient weight loss in potential donors, and during the subsequent follow-up, with lifestyle change programmes if necessary.
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.
Esta guía de recomendaciones para el TR de donante vivo (TRDV) es un documento elaborado con el patrocinio de la Sociedad Española de Nefrología, la Sociedad Española de Trasplantes y la Organización Nacional de Trasplantes que actualiza la calidad de la evidencia disponible para ofrecer el mejor tratamiento de la insuficiencia renal crónica cuando se disponga de un donante vivo potencial. El objetivo principal de esta guía es proporcionar a los profesionales con responsabilidad en los estudios previos del donante vivo y del receptor trasplantado, las mejores herramientas para tomar decisiones en beneficio del donante vivo y del receptor del trasplante.
Además, en el contexto actual del TR, el donante vivo debe recuperar el protagonismo que alcanzó en un pasado reciente. Para ello, las nuevas modalidades de donación HLA y/o ABO incompatible, así como la donación cruzada disponibles en diversos centros con experiencia en TRDV, son oportunidades adicionales para el tratamiento de enfermos renales que tienen un donante incompatible.
Los buenos resultados en supervivencia del paciente y del injerto están ampliando las circunstancias de aceptación de donantes vivos de riñón, incluyendo donantes de mayor edad y otros con algunos condicionantes que incluyen antecedentes o alteraciones límite que, cuando son evaluados con criterios objetivos, pueden aportar un numero adicional de trasplantes.
No se ha obviado en esta guía que el TRDV puede representar algún riesgo para el que dona. Estos problemas que pueden aparecer a corto o largo plazo tienen que ser objeto principal de valoración previa a la donación y presentados al potencial donante para que en ejercicio de su autonomía los asuma o rechace. La experiencia acumulada en los últimos años ha permitido avanzar en el análisis de riesgos para preservar la salud de los donantes, aspecto que debe estar siempre presente en los responsables de programas de TRDV cuando se procede al estudio de idoneidad de un potencial donante.
Finalmente, esta guía ha sido estructurada para facilitar la toma de decisiones con recomendaciones y sugerencias ante incertidumbres derivadas de los resultados en los exhaustivos estudios predonación. Y todo ello, con el objetivo de que el consentimiento informado que debe certificar la calidad de los estudios y la información proporcionada a donante y receptor, alcancen las mayores garantías posibles.
Long-term Medical Outcomes of Living Kidney Donors
2022, Mayo Clinic Proceedings
Citation Excerpt :
The risk was similar for male and female donors, African American and White donors, and across the baseline eGFR spectrum. In a separate analysis, Locke et al83 also reported that high BMI at donation was associated with increased mortality. In a study from the University of Minnesota, Ibrahim et al84 reported that of 4014 LDs, 309 (7.7%) developed diabetes a median of 18 years after donation.
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.
Chronic Kidney Disease Risk Profile in Renal Donors in Aguascalientes, Mexico: A Retrospective Cohort Study
2022, Transplantation Proceedings
Citation Excerpt :
A most significant problem in our population is the great proportion of overweight and obesity. The relation between the ESRD risk and mortality in these patients is clear [14,15]. Whether the donor status confers an added risk for death in obese patients remains to be determined [15].
In the last decade, kidney donation has been recognized as a risk factor for end-stage renal disease (ESRD). ESRD risk calculators have been recently perfected in North American populations. In Mexico, the rates of overweight, obesity, and diabetes mellitus (DM) are among the highest worldwide; nevertheless, most kidney transplants are obtained from living donors. This study aims to describe the risk profile for chronic kidney disease (CKD) development in kidney donors in a highly active transplant center in Central Mexico.
We conducted a retrospective, observational, descriptive cohort study of kidney donors followed at the Hospital Centenario Miguel Hidalgo (CHMH). We used the pretransplant CKD risk calculator at 15 years and over a lifetime (www.transplantmodels.com/esrdrisk). Aside from the calculator of kidney failure risk, we also used the calculator for postdonation CKD risk (www.transplantmodels.com/donesrd/). Factors associated with a glomerular filtration rate (GFR) <60 mL/min were evaluated by univariate and multivariate analysis.
The study included 543 donors. The average follow-up period was 1.7 years (±2.7) with a median of 0.7 years (interquartile range, 0.2-2.1). The average predicted risk for ESRD development at 15 years was 0.08% (±0.1); 25.6% had a risk >0.1%, and only 1 patient had a risk >1%. The lifetime ESRD risk was 0.62% (±0.5); 15% had a risk >1%, and the greatest risk was 3.5%. The median of patients at risk of developing postdonation ESRD was 1 in 10,000 donors (0.6-1.5) at 5 years, 5.7 in 10,000 donors (3.5-8.8) at 10 years, 15 in 10,000 donors (9.1-23.2) at 15 years, and 31 in 10,000 donors (18.9-47.7) at 20 years. During the follow-up period, 52 patients developed a GFR of <60 mL/min. Both risk estimation formulas were significantly associated with a GFR of <60 mL/min. Among the individual factors, the GFR (hazard ratio 0.96, 95% confidence interval 0.94-0.97, P < .001) and the urinary albumin to creatinine ratio (hazard ratio 1.009, 95% confidence interval 1.005-1.01, P < .001) remained statistically significant.
The risk of ESRD in kidney donors in Aguascalientes, Mexico, is similar to that described in the United States. Risk calculators are an indispensable decision-making tool to better understand kidney donors in our milieu.
Living donor nephrectomy: The French guidelines from CTAFU
2021, Progres en Urologie
Proposer des recommandations chirurgicales pour la néphrectomie dans le cadre d’un don de rein pour transplantation.
Une revue de la littérature (Medline) avec approche systématique a été conduite par le CTAFU concernant les éléments d’évaluation fonctionnelle et anatomique du candidat au don, les options dans le choix du rein à prélever et des différentes techniques chirurgicales, en évaluant les références et leur niveau de preuve.
Les recommandations précisent le cadre légal et réglementaire du don de rein. Une évaluation de qualité du candidat au don est un des prérequis indispensable à la sécurité du donneur qui est une priorité absolue. L’impact de la néphrectomie sur la fonction rénale doit être évalué. En cas de vascularisation modale des deux reins sans différence relative de fonction ni anomalie urologique, le rein gauche doit être prélevé afin d’avoir une veine plus longue. Les techniques chirurgicales de néphrectomie mini-invasives ont pour avantages une récupération plus rapide, une hospitalisation plus courte et une diminution des douleurs pour le donneur. Ces techniques mini-invasives doivent être proposées à la place d’une voie incisionnelle ouverte.
Ces recommandations françaises doivent contribuer à améliorer la prise en charge chirurgicale des patients candidats à un don de rein.
To propose surgical recommendations for living donor nephrectomy.
Following a systematic approach, a review of the literature (Medline) was conducted by the CTAFU regarding functional and anatomical assessment of kidney donors, including which side the kidney should be harvested from. Distinct surgical techniques and approaches were evaluated. References were considered with a predefined process to propose recommendations with the corresponding levels of evidence.
The recommendations clarify the legal and regulatory framework for kidney donation in France. A rigorous assessment of the donor is one of the essential prerequisites for donor safety. The impact of nephrectomy on kidney function needs to be anticipated. In case of modal vascularization of both kidneys without a relative difference in function or urologic abnormality, removal of the left kidney is the preferred choice to favor a longer vein. Mini-invasive approaches for nephrectomy provide faster donor recovery, less donor pain and shorter hospital stay than open surgery.
These French recommendations must contribute to improving surgical management of candidates for kidney donation.
Invited Commentary: Concurrent nephrectomy and bariatric surgery for obese living kidney donors
2019, Surgery (United States)

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: Supported by National Institutes of Health grant numbers K23-DK103918 (Jayme Locke), R01-DK113980 (Jayme Locke), and K01DK-K01-DK101677 (Allan Massie); K24-DK101828 (Dorry Segev) and he American Society of Transplantation Clinical Scientist Faculty Development Grant (Jayme Locke).

: J.E.L. and D.L.S. designed the study. R.D.R., P.A.M., A.B.M., and J.J.S. performed the data analyses. J.E.L. drafted and revised the manuscript. R.D.R., P.A.M., A.B.M., D.S., V.K., B.A.S., M.N.M., J.J.S., C.E..L, and D.L.S. assisted with interpretation of results and critically revised the manuscript. All authors approved the final version of the manuscript.

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TransplantationObesity and long-term mortality risk among living kidney donors

Abstract

Background

Methods

Results

Conclusion

Introduction

Section snippets

Methods

Results

Discussion

Acknowledgments

Conflict of interest

Am J Kidney Dis

Kidney Int

Am J Kidney Dis

Kidney Int

Am J Transplant

Kidney Int

Am J Transplant

The decline in living kidney donation in the United States: Random variation or cause for concern?

Transplantation

Prevalence of obesity among adults and youth: United States, 2011–2014

NCHS Data Brief

The enlarging body of evidence: Obesity and chronic kidney disease

J Am Soc Nephrol

Obesity and cardiovascular disease: Pathophysiology, evaluation, and effect of weight loss: An update of the 1997 American Heart Association Scientific Statement on Obesity and Heart Disease from the Obesity Committee of the Council on Nutrition, Physical Activity, and Metabolism

Circulation

Estimating the risk of type-2 diabetes using obese-years in a contemporary population of the Framingham Study

Glob Health Action

Obesity and risk for chronic renal failure

J Am Soc Nephrol

Predictors of new-onset kidney disease in a community-based population

JAMA

Transplantation
Obesity and long-term mortality risk among living kidney donors