Kidney-Failure Risk Projection for the Living Kidney-Donor Candidate

Quantifying Postdonation Risk of ESRD in Living Kidney Donors

Studies have estimated the average risk of postdonation ESRD for living kidney donors in the United States, but personalized estimation on the basis of donor characteristics remains unavailable. We studied 133,824 living kidney donors from 1987 to 2015, as reported to the Organ Procurement and Transplantation Network, with ESRD ascertainment via Centers for Medicare and Medicaid Services linkage, using Cox regression with late entries. Black race (hazard ratio [HR], 2.96; 95% confidence interval [95% CI], 2.25 to 3.89; P<0.001) and male sex (HR, 1.88; 95% CI, 1.50 to 2.35; P<0.001) was associated with higher risk of ESRD in donors. Among nonblack donors, older age was associated with greater risk (HR per 10 years, 1.40; 95% CI, 1.23 to 1.59; P<0.001). Among black donors, older age was not significantly associated with risk (HR, 0.88; 95% CI, 0.72 to 1.09; P=0.3). Greater body mass index was associated with higher risk (HR per 5 kg/m2, 1.61; 95% CI, 1.29 to 2.00; P<0.001). Donors who had a first-degree biological relationship to the recipient had increased risk (HR, 1.70; 95% CI, 1.24 to 2.34; P<0.01). C-statistic of the model was 0.71. Predicted 20-year risk of ESRD for the median donor was only 34 cases per 10,000 donors, but 1% of donors had predicted risk exceeding 256 cases per 10,000 donors. Risk estimation is critical for appropriate informed consent and varies substantially across living kidney donors. Greater permissiveness may be warranted in older black candidate donors; young black candidates should be evaluated carefully.

Readability, content analysis, and racial/ethnic diversity of online living kidney donation information

More than three-fourths of adults in the USA use the Internet to access health-related information. Adults exploring the possibility of living donation should have access to online content that is readable and comprehensive. We simulated a search of online information about living kidney donation and evaluated readability, topics covered, and racial/ethnic diversity of 21 websites meeting inclusion criteria (eg, hosted by a nonprofit or patient advocacy organization, English content, based in USA). Using standard readability metrics, 62% of sites were classified as "Difficult to read" and none achieved the recommended reading level of sixth grade. On average, websites covered 18.5 (62%) of 30 recommended information topics (range: 7 to 28) and only 2.1 (23%) of 9 racial/ethnic diversity items (range: 0 to 6). Overall, the most common nonprofit or patient advocacy organization websites do not meet the readability standards established by the National Institutes of Health and the American Medical Association, many lack fundamental information about living kidney donation, and most are not racially/ethnically diverse. We encourage the transplant community to consider playing a more active role in improving the overall quality of online information disseminated to the general public. Further, there is a need to more critically examine the accuracy of online living donation content in future investigations.

Summary of Kidney Disease: Improving Global Outcomes (KDIGO) Clinical Practice Guideline on the Evaluation and Care of Living Kidney Donors

Kidney Disease: Improving Global Outcomes (KDIGO) engaged an evidence review team and convened a work group to produce a guideline to evaluate and manage candidates for living kidney donation. The evidence for most guideline recommendations is sparse and many "ungraded" expert consensus recommendations were made to guide the donor candidate evaluation and care before, during, and after donation. The guideline advocates for replacing decisions based on assessments of single risk factors in isolation with a comprehensive approach to risk assessment using the best available evidence. The approach to simultaneous consideration of each candidate's profile of demographic and health characteristics advances a new framework for assessing donor candidate risk and for defensible shared decision making.

KDIGO Clinical Practice Guideline on the Evaluation and Care of Living Kidney Donors

The 2017 Kidney Disease: Improving Global Outcomes (KDIGO) Clinical Practice Guideline on the Evaluation and Care of Living Kidney Donors is intended to assist medical professionals who evaluate living kidney donor candidates and provide care before, during and after donation. The guideline development process followed the Grades of Recommendation Assessment, Development, and Evaluation (GRADE) approach and guideline recommendations are based on systematic reviews of relevant studies that included critical appraisal of the quality of the evidence and the strength of recommendations. However, many recommendations, for which there was no evidence or no systematic search for evidence was undertaken by the Evidence Review Team, were issued as ungraded expert opinion recommendations. The guideline work group concluded that a comprehensive approach to risk assessment should replace decisions based on assessments of single risk factors in isolation. Original data analyses were undertaken to produce a "proof-in-concept" risk-prediction model for kidney failure to support a framework for quantitative risk assessment in the donor candidate evaluation and defensible shared decision making. This framework is grounded in the simultaneous consideration of each candidate's profile of demographic and health characteristics. The processes and framework for the donor candidate evaluation are presented, along with recommendations for optimal care before, during, and after donation. Limitations of the evidence are discussed, especially regarding the lack of definitive prospective studies and clinical outcome trials. Suggestions for future research, including the need for continued refinement of long-term risk prediction and novel approaches to estimating donation-attributable risks, are also provided.In citing this document, the following format should be used: Kidney Disease: Improving Global Outcomes (KDIGO) Living Kidney Donor Work Group. KDIGO Clinical Practice Guideline on the Evaluation and Care of Living Kidney Donors. Transplantation. 2017;101(Suppl 8S):S1-S109.

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.

Design and Methods of the Korean Organ Transplantation Registry

Background

Beneficial aspects of solid organ transplantation, which encompass survival benefit, improved quality of life, and cost efficacy, have been clearly demonstrated. However, regional and ethnic differences require further studies to identify prognostic factors and transplant outcomes against various backgrounds. After previous efforts of a nationwide, retrospective study on the kidney transplant outcomes in Korea, a new prospective-designed version of the Korean Organ Transplantation Registry (KOTRY) was launched in 2014.

Methods

Cohorts of kidney, liver, heart, lung, and pancreas transplantation were developed. Data on demographics, comorbid conditions, laboratory tests, including tissue typing and panel reactive antibody tests, immunosuppressive regimen followed, concentration and dosage of immunosuppressants, allograft rejection type, infectious events, cardiovascular outcomes, malignancies, donor comorbidity, and outcomes of living donors are collected. Longitudinal data collection is based on a regular annual interval, and blood samples are collected before organ transplantation and again at 1 and 3 years posttransplantation. To enhance data quality, a predefined data verification system operates on a Web-based database, and transplant center users receive regular education about updates. Data are cleansed thrice a year, and feedback given to centers about outlier values and missing data. Annual auditing is conducted.

Results

Currently, 59 centers are participating in KOTRY. The estimated annual enrollment is more than 2000 cases.

Conclusions

KOTRY, as a systematic Korean transplant cohort, is expected to provide important information on Asian organ transplantation. The processes used to establish KOTRY provide a good model for launching new nationwide transplant cohort studies.

Physician perceptions about living organ donation in patients with Amyotrophic Lateral Sclerosis

OBJECTIVES

Patients with Amyotrophic Lateral Sclerosis (ALS) have expressed desire to become living organ donors but are unable to do so with current organ donation policies. Our objective is to assess ALS patient's interest in organ donation, and perceived concerns of this practice by ALS neurologists.

PATIENTS AND METHODS

An electronic survey was administered to ALS neurologists across the United States regarding living organ donation in ALS patients prior to respiratory failure.

RESULTS

52 complete responses were received from 121 invites. 67% (35/52) of neurologists expressed no concerns about living organ donation in ALS patients, and 33% had concerns. The concerns related to respiratory failure, anesthesia exposure and renal dysfunction. With their concerns addressed, 71% of neurologists reported that they would endorse living organ donation. 49% of neurologists reported being asked by a patient for information regarding living organ donation. ALS neurologists felt that 22.8% of ALS patients (median 19%) would be interested in learning more about organ donation, while only 6% of neurologists broach this subject with their patients.

CONCLUSION

Our results indicate that 1 in every 4 ALS patients may be interested in exploring options for living organ donation, and this topic is not routinely addressed by ALS clinics. These results indicate an unexplored area of patient interest. To honor a patient's wishes to donate, the transplant community will have to accommodate living organ donation from terminally ill patients, and address neurologist concerns. Such a practice could benefit two groups of patients.

Risk of End-Stage Renal Disease in HIV-Positive Potential Live Kidney Donors

New federal regulations allow HIV-positive individuals to be live kidney donors; however, potential candidacy for donation is poorly understood given the increased risk of end-stage renal disease (ESRD) associated with HIV infection. To better understand this risk, we compared the incidence of ESRD among 41 968 HIV-positive participants of North America AIDS Cohort Collaboration on Research and Design followed for a median of 5 years with the incidence of ESRD among comparable HIV-negative participants of National Health and Nutrition Examination III followed for a median of 14 years. We used risk associations from multivariable Cox proportional hazards regression to derive cumulative incidence estimates for selected HIV-positive scenarios (no history of diabetes, hypertension, AIDS, or hepatitis C virus coinfection) and compared these estimates with those from similarly selected HIV-negative scenarios. For 40-year-old HIV-positive individuals with health characteristics that were similar to those of age-matched kidney donors, viral load <400 copies/mL, and CD4⁺ count ≥500 cells/μL, the 9-year cumulative incidence of ESRD was higher than that of their HIV-negative peers, yet still low: 2.5 versus 1.1 per 10 000 among white women, 3.0 versus 1.3 per 10 000 among white men, 13.2 versus 3.6 per 10 000 among black women, and 15.8 versus 4.4 per 10 000 among black men. HIV-positive individuals with no comorbidities and well-controlled disease may be considered low-risk kidney donor candidates.

[New scores in renal transplantation: How can we use them?]

In renal transplant medicine, several scores have been recently developed in order to help decision-making in clinical practice. The aim of this update is to focus on these new scores that allow to better estimate the quality of the renal transplant, to refine the allocation policy, to help registration of old recipients on the waiting list, or to evaluate the risk to develop end-stage renal failure after living donation.

Campaigning for Organ Donation at Mosques

There is a trend of recruiting faith leaders at mosques to overcome religious barriers to organ donation, and to increase donor registration among Muslims. Commentators have suggested that Muslims are not given enough information about organ donation in religious sermons or lectures delivered at mosques. Corrective actions have been recommended, such as funding campaigns to promote organ donation, and increasing the availability of organ donation information at mosques. These actions are recommended despite published literature expressing safety concerns (i.e., do no harm) in living and end-of-life organ donation. Living donors require life-long medical follow-up and treatment for complications that can appear years later. Scientific and medical controversies persist regarding the international guidelines for death determination in end-of-life donation. The medical criteria of death lack validation and can harm donors if surgical procurement is performed without general anesthesia and before biological death. In the moral code of Islam, the prevention of harm holds precedence over beneficence. Moral precepts described in the Quran encourage Muslims to be beneficent, but also to seek knowledge prior to making practical decisions. However, the Quran also contains passages that demand honesty and truthfulness when providing information to those who are seeking knowledge. Currently, information is limited to that which encourages donor registration. Campaigning for organ donation to congregations in mosques should adhere to the moral code of complete, rather than selective, disclosure of information. We recommend as a minimal standard the disclosure of risks, uncertainties, and controversies associated with the organ donation process.

Connecting tubule glomerular feedback mediates tubuloglomerular feedback resetting after unilateral nephrectomy

Unilaterally nephrectomized rats (UNx) have higher glomerular capillary pressure (P_GC) that can cause significant glomerular injury in the remnant kidney. P_GC is controlled by the ratio of afferent (Af-Art) and efferent arteriole resistance. Af-Art resistance in turn is regulated by two intrinsic feedback mechanisms: 1) tubuloglomerular feedback (TGF) that causes Af-Art constriction in response to increased NaCl in the macula densa; and 2) connecting tubule glomerular feedback (CTGF) that causes Af-Art dilatation in response to an increase in NaCl transport in the connecting tubule via the epithelial sodium channel (ENaC). Resetting of TGF post-UNx can allow systemic pressure to be transmitted to the glomerulus and cause renal damage, but the mechanism behind this resetting is unclear. Since CTGF is an Af-Art dilatory mechanism, we hypothesized that CTGF is increased after UNx and contributes to TGF resetting. To test this hypothesis, we performed UNx in Sprague-Dawley (8) rats. Twenty-four hours after surgery, we performed micropuncture of individual nephrons and measured stop-flow pressure (P_SF). P_SF is an indirect measurement of P_GC. Maximal TGF response at 40 nl/min was 8.9 ± 1.24 mmHg in sham-UNx rats and 1.39 ± 1.02 mmHg in UNx rats, indicating TGF resetting after UNx. When CTGF was inhibited with the ENaC blocker benzamil (1 μM/l), the TGF response was 12.29 ± 2.01 mmHg in UNx rats and 13.03 ± 1.25 mmHg in sham-UNx rats, indicating restoration of the TGF responses in UNx. We conclude that enhanced CTGF contributes to TGF resetting after UNx.

GFR Evaluation in Living Kidney Donor Candidates

Evaluation of GFR, required in the evaluation of living kidney donor candidates, is now receiving increasing emphasis because recent data demonstrate increased risk of kidney disease after donation, including a small increase in the risk of kidney failure. The international guideline development group, Kidney Disease Improving Global Outcomes, recently published a comprehensive set of recommendations for living donor evaluation, with three recommendations regarding GFR. (1) Donor candidacy is evaluated in light of long-term risk, in which GFR is one of many factors. ESRD is considered a central outcome, and a method for estimating long-term risk of ESRD in donor candidates is described. (2) Two GFR thresholds are used for decision-making: a high threshold (≥90 ml/min per 1.73 m2) to accept and a low threshold (<60 ml/min per 1.73 m2) to decline, with 60-89 ml/min per 1.73 m2 as an intermediate range in which the decision to accept or decline is made on the basis of factors in addition to GFR. (3) GFR is evaluated using several methods available at the transplant center, including estimating equations and clearance measurements. We review the rationale for the guideline recommendations, principles of GFR measurement and estimation, and our suggestions for implementation.

Long-Term Medical and Psychosocial Outcomes in Living Liver Donors

Due to the enduring organ shortage, living donor liver transplantation has been a valuable treatment strategy for advanced liver disease patients for over 20 years. A variety of reviews have summarized the extensive data now available on medical and psychosocial risks to living donors in the aftermath of donation. However, evidence on donor medical and psychosocial outcomes beyond the first year postdonation has not been synthesized in any previous review. The evidence base on such "long-term" outcomes has been growing in recent years. A review of this evidence would therefore be timely and could serve as an important resource to assist transplant centers in their efforts to fully educate prospective donors and gain informed consent, as well as develop appropriate postdonation clinical care and surveillance plans. We reviewed recent literature on long-term donor outcomes, considering (a) medical outcomes, including mortality risk, rates of complications, abnormalities detected in laboratory testing, and the progress of liver regeneration; and (b) donor-reported psychosocial outcomes reflecting physical, emotional, and interpersonal/socioeconomic well-being, as well as overall health-related quality of life. We summarize limitations and gaps in available evidence, and we provide recommendations for future research and clinical care activities focused on long-term outcomes in liver donors.

Transplant genetics and genomics

Ever since the discovery of the major histocompatibility complex, scientific and clinical understanding in the field of transplantation has been advanced through genetic and genomic studies. Candidate-gene approaches and recent genome-wide association studies (GWAS) have enabled a deeper understanding of the complex interplay of the donor-recipient interactions that lead to transplant tolerance or rejection. Genetic analysis in transplantation, when linked to demographic and clinical outcomes, has the potential to drive personalized medicine by enabling individualized risk stratification and immunosuppression through the identification of variants associated with immune-mediated complications, post-transplant disease or alterations in drug-metabolizing genes.

What is the significance of end-stage renal disease risk estimation in living kidney donors?

Two end-stage renal disease (ESRD) risk calculators were recently developed by Grams et al., and Ibrahim et al. to calculate ESRD risk before donation among living kidney donors. However, those calculators have never been studied among potential donors for whom donation was refused due to medical contraindications and compared to a group of donors. We compared 15-year and lifetime ESRD risk of donors and nondonors due to medical cause as estimated by those two calculators. Nondonors due to medical cause (n = 27) had a significantly higher 15-year ESRD risk compared to donors (n = 288) with both calculators (0.25 vs. 0.14, P < 0.001 for that developed by Grams et al. and 2.21 vs. 1.43, P = 0.002 for that developed by Ibrahim et al.). On the contrary, lifetime ESRD risk was not significantly different between the two groups. At both times (15 years and lifetime), we observed a significant overlap of ESRD risk between the two groups. ESRD risk calculators could be complementary to standard screening strategy but cannot be used alone to accept or decline donation.

Living Organ Donation and Informed Consent in the United States: Strategies to Improve the Process

About 6,000 individuals participate in the U.S. transplant system as a living organ donor each year. Organ donation (most commonly a kidney or part of liver) by living individuals is a unique procedure, where healthy patients undergo a major surgical operation without any direct functional benefit to themselves. In this article, the authors explore how the ideal of informed consent guides education and evaluation for living organ donation. The authors posit that informed consent for living organ donation is a process. Though the steps in this process are partially standardized through national health policy, they can be improved through institutional structures at the local, transplant center-level. Effective structures and practices aimed at supporting and promoting comprehensive informed consent provide more opportunities for candidates to ask questions about the risks and benefits of living donation and to opt out voluntarily Additionally, these practices could enable new ways of measuring knowledge and improving the consent process.

Strategies for assessing GFR and albuminuria in the living kidney donor evaluation

PURPOSE OF REVIEW

The international guideline development group Kidney Disease Improving Global Outcomes (KDIGO) recently published a comprehensive set of recommendations for living donor evaluation which contains a new framework for decision making in the evaluation of kidney donor candidates.

RECENT FINDINGS

The guidelines recommend that decisions to accept or decline a candidate donor should be based on incorporation of multiple sources of information pertaining to the donor candidate's likelihood of serious adverse outcomes after donation. Two central components of assessment of risk are glomerular filtration rate (GFR) and albuminuria. We describe strategies for clinical decision making in assessment of GFR and albuminuria in the evaluation of living kidney donor candidates. Our premise is that all measurements will contain error; no single test result should lead to a decision to accept or decline a donor candidate.

SUMMARY

A structured apporach to use of information from multiple sources (e.g. estimated and measured GFR, estimated and measured albuminuria) aids in test interpretation and can lead to increased accuracy of testing and efficiency of evaluation strategies.

Decision aids to increase living donor kidney transplantation

PURPOSE OF REVIEW

For the more than 636,000 adults with end-stage renal disease (ESRD) in the U.S., kidney transplantation is the preferred treatment compared to dialysis. Living donor kidney transplantation (LDKT) comprised 31% of kidney transplantations in 2015, an 8% decrease since 2004. We aimed to summarize the current literature on decision aids that could be used to improve LDKT rates.

RECENT FINDINGS

Decision aids are evidence-based tools designed to help patients and their families make difficult treatment decisions. LDKT decision aids can help ESRD patients, patients' family and friends, and healthcare providers engage in treatment decisions and thereby overcome multifactorial LDKT barriers.

SUMMARY

We identified 12 LDKT decision aids designed to provide information about LDKT, and/or to help ESRD patients identify potential living donors, and/or to help healthcare providers make decisions about treatment for ESRD or living donation. Of these, 4 were shown to be effective in increasing LDKT, donor inquiries, LDKT knowledge, and willingness to discuss LDKT. Although each LDKT decision aid has limitations, adherence to decision aid development guidelines may improve decision aid utilization and access to LDKT.

Evaluation of renal function in a specific population of living kidney donors

BACKGROUND

The increase in candidates for kidney transplant has led to growth in the number of living donor transplants. Therefore, studies that adequately evaluate the possible long-term consequences of elective transplant nephrectomy are needed.

OBJECTIVE

To evaluate the possible long-term adverse effects of transplant nephrectomy on the renal function of living kidney donors.

DESIGN

A cross-sectional study.

PARTICIPANTS

Thirty-three living kidney donors registered in the transplant programme of a centre in Alagoas, Brazil.

MEASUREMENTS

Demographic characteristics, anthropometric measures, clinical data and biomarkers (creatinine, eGFR, microalbuminuria, cholesterol and triglycerides) were measured. Creatinine clearance was calculated using the Cockcroft-Gault and Modification of Diet in Renal Disease formulae.

RESULTS

Of the 33 individuals, 63.63% were female, and the median age was 45 years. Additionally, 24.24% of these individuals had altered blood pressure, 39.39% had altered abdominal circumference (AC) and 36.36% were obese, with a body mass index ≥30. Furthermore, 33.33% of these individuals had elevated triglyceride levels. The average eGFR was 97.33 (33.03-175.9) ml/min/1.73 m² (CG) and 84.14 (29.4-131) ml/min/1.73 m² (MDRD). The microalbuminuria level was altered in 12.12% patients.

CONCLUSION

Kidney donation is unquestionably a safe procedure. However, a better understanding of the long-term consequences of living donor kidney transplantation is still needed. This knowledge may have important implications for the follow-up of these patients. Our study has demonstrated a non-negligible presence of an early marker of glomerular injury and a decrease in the GFR of some patients, thereby reinforcing the proposal for long-term follow-up of living kidney donors.

Acceptability of older adults as living kidney donors

PURPOSE OF REVIEW

Kidney transplantation from a living kidney donor (LKD) is associated with better long-term survival and quality of life for a patient with end-stage renal disease (ESRD) than dialysis. We reviewed recent literature on the acceptability and outcomes of older adults as LKDs, which may be misunderstood in routine care.

RECENT FINDINGS

Studies report that receiving a kidney from an older LKD is associated with worse recipient and graft survival compared with receiving a kidney from a younger LKD, but similar recipient and graft survival to receiving a kidney from a standard criteria deceased donor. A kidney from a younger vs. older LKD results in better graft survival in younger recipients, whereas the graft survival is similar in older recipients. Compared with healthy matched nondonors, older LKDs have a similar risk of death and cardiovascular disease and the absolute risk of ESRD after 15 years remains less than 1%. The estimated predonation and postdonation lifetime risk of ESRD varies by age, sex and race with lower incidences in individuals who are older, female and white (vs. African-American).

SUMMARY

Donor and recipient outcomes from several studies support the acceptability of older adults as LKDs.

Glomerular Hyperfiltration in Diabetes: Mechanisms, Clinical Significance, and Treatment

An absolute, supraphysiologic elevation in GFR is observed early in the natural history in 10%-67% and 6%-73% of patients with type 1 and type 2 diabetes, respectively. Moreover, at the single-nephron level, diabetes-related renal hemodynamic alterations-as an adaptation to reduction in functional nephron mass and/or in response to prevailing metabolic and (neuro)hormonal stimuli-increase glomerular hydraulic pressure and transcapillary convective flux of ultrafiltrate and macromolecules. This phenomenon, known as glomerular hyperfiltration, classically has been hypothesized to predispose to irreversible nephron damage, thereby contributing to initiation and progression of kidney disease in diabetes. However, dedicated studies with appropriate diagnostic measures and clinically relevant end points are warranted to confirm this assumption. In this review, we summarize the hitherto proposed mechanisms involved in diabetic hyperfiltration, focusing on ultrastructural, vascular, and tubular factors. Furthermore, we review available evidence on the clinical significance of hyperfiltration in diabetes and discuss currently available and emerging interventions that may attenuate this renal hemodynamic abnormality. The revived interest in glomerular hyperfiltration as a prognostic and pathophysiologic factor in diabetes may lead to improved and timely detection of (progressive) kidney disease, and could provide new therapeutic opportunities in alleviating the renal burden in this population.

Kidney and innate immunity

Innate immune system is an important modulator of the inflammatory response during infection and tissue injury/repair. The kidney as a vital organ with high energy demand plays a key role in regulating the disease related metabolic process. Increasing research interest has focused on the immune pathogenesis of many kidney diseases. However, innate immune cells such as dendritic cells, macrophages, NK cells and a few innate lymphocytes, as well as the complement system are essential for renal immune homeostasis and ensure a coordinated balance between tissue injury and regeneration. The innate immune response provides the first line of host defense initiated by several classes of pattern recognition receptors (PRRs), such as membrane-bound Toll-like receptors (TLRs) and nucleotide-binding oligomerization domain (NOD)-like receptors (NLRs), together with inflammasomes responsible for early innate immune response. Although the innate immune system is well studied, the research on the detailed relationship between innate immunity and kidney is still very limited. In this review, we will focus on the innate immune sensing system in renal immune homeostasis, as well as the corresponding pathogenesis of many kidney diseases. The pivotal roles of innate immunity in renal injury and regeneration with special emphasis on kidney disease related immunoregulatory mechanism are also discussed.

Nephron number, hypertension, and CKD: physiological and genetic insight from humans and animal models

The kidneys play a vital role in the excretion of waste products and the regulation of electrolytes, maintenance of acid-base balance, regulation of blood pressure, and production of several hormones. Any alteration in the structure of the nephron (basic functional unit of the kidney) can have a major impact on the kidney's ability to work efficiently. Progressive decline in kidney function can lead to serious illness and ultimately death if not treated by dialysis or transplantation. While there have been numerous studies that implicate lower nephron numbers as being an important factor in influencing susceptibility to developing hypertension and chronic kidney disease, a direct association has been difficult to establish because of three main limitations: 1) the large variation in nephron number observed in the human population; 2) no established reliable noninvasive methods to determine nephron complement; and 3) to date, nephron measurements have been done after death, which doesn't adequately account for potential loss of nephrons with age or disease. In this review, we will provide an overview of kidney structure/function, discuss the current literature for both humans and other species linking nephron deficiency and cardio-renal complications, as well as describe the major molecular signaling factors involved in nephrogenesis that modulate variation in nephron number. As more detailed knowledge about the molecular determinants of nephron development and the role of nephron endowment in the cardio-renal system is obtained, it will hopefully provide clinicians the ability to accurately identify people at risk to develop CKD/hypertension and lead to a shift in patient care from disease treatment to prevention.

Hyperfiltration-associated biomechanical forces in glomerular injury and response: Potential role for eicosanoids

Hyperfiltration is a well-known risk factor in progressive loss of renal function in chronic kidney disease (CKD) secondary to various diseases. A reduced number of functional nephrons due to congenital or acquired cause(s) results in hyperfiltration in the remnant kidney. Hyperfiltration-associated increase in biomechanical forces, namely pressure-induced tensile stress and fluid flow-induced shear stress (FFSS) determine cellular injury and response. We believe the current treatment of CKD yields limited success because it largely attenuates pressure-induced tensile stress changes but not the effect of FFSS on podocytes. Studies on glomerular podocytes, tubular epithelial cells and bone osteocytes provide evidence for a significant role of COX-2 generated PGE₂ and its receptors in response to tensile stress and FFSS. Preliminary observations show increased urinary PGE₂ in children born with a solitary kidney. FFSS-induced COX2-PGE₂-EP₂ signaling provides an opportunity to identify targets and, for developing novel agents to complement currently available treatment.

Understanding and Communicating Medical Risks for Living Kidney Donors: A Matter of Perspective

Communicating the current knowledge of medical outcomes after live kidney donation necessary to support donor candidates in well informed decision-making requires grounding in perspectives of comparison. Baseline risk (without donating), risk attributable to donation, and absolute risk (after donating) need to be considered. Severe perioperative complications and death are rare, but vary by demographic, clinical, and procedure factors. Innovative capture of "healthy" controls designed to simulate donor selection processes has identified higher risk of ESRD attributable to donation in two studies; importantly, however, the absolute 15-year ESRD incidence in donors remains very low (0.3%). In the first decade after donation, the risk of all-cause mortality and cardiovascular events is no higher than in healthy nondonors. Pregnancies in donors may incur attributable risk of gestational hypertension or preeclampsia (11% versus 5% incidence in one study). A modest rise in uric acid levels beginning early after donation, and a small (1.4%) increase in the 8-year incidence of gout, have also been reported in comparisons to healthy nondonors. As in the general population, postdonation outcomes vary by race, sex, and age. Efforts to improve the counseling and selection of living donors should focus on developing tools for tailored risk prediction according to donor characteristics, and ideally, compared with similar healthy nondonors.

Obesity increases the risk of end-stage renal disease among living kidney donors

Determining candidacy for live kidney donation among obese individuals remains challenging. Among healthy non-donors, body mass index (BMI) above 30 is associated with a 16% increase in risk of end-stage renal disease (ESRD). However, the impact on the ESRD risk attributable to donation and living with only one kidney remains unknown. Here we studied the risk of ESRD associated with obesity at the time of donation among 119 769 live kidney donors in the United States. Maximum follow-up was 20 years. Obese (BMI above 30) live kidney donors were more likely male, African American, and had higher blood pressure. Estimated risk of ESRD 20 years after donation was 93.9 per 10 000 for obese; significantly greater than the 39.7 per 10 000 for non-obese live kidney donors. Adjusted for age, sex, ethnicity, blood pressure, baseline estimated glomerular filtration rate, and relationship to recipient, obese live kidney donors had a significant 86% increased risk of ESRD compared to their non-obese counterparts (adjusted hazard ratio 1.86; 95% confidence interval 1.05-3.30). For each unit increase in BMI above 27 kg/m² there was an associated significant 7% increase in ESRD risk (1.07, 1.02-1.12). The impact of obesity on ESRD risk was similar for male and female donors, African American and Caucasian donors, and across the baseline estimated glomerular filtration rate spectrum. These findings may help to inform selection criteria and discussions with persons considering living kidney donation.

Patterns of End-Stage Renal Disease Caused by Diabetes, Hypertension, and Glomerulonephritis in Live Kidney Donors

Inferences about late risk of end-stage renal disease (ESRD) in live kidney donors have been extrapolated from studies averaging <10 years of follow-up. Because early (<10 years) and late (≥10 years) postdonation ESRD may differ by causal mechanism, it is possible that extrapolations are misleading. To better understand postdonation ESRD, we studied patterns of common etiologies including diabetes, hypertension and glomerulonephritis (GN; as reported by providers) using donor registry data linked to ESRD registry data. Overall, 125 427 donors were observed for a median of 11.0 years (interquartile range 5.3-15.7 years; maximum 25 years). The cumulative incidence of ESRD increased from 10 events per 10 000 at 10 years after donation to 85 events per 10 000 at 25 years after donation (late vs. early ESRD, adjusted for age, race and sex: incidence rate ratio [IRR] _1.3 1.7_2.3 [subscripts are 95% confidence intervals]). Early postdonation ESRD was predominantly reported as GN-ESRD; however, late postdonation ESRD was more frequently reported as diabetic ESRD and hypertensive ESRD (IRR _2.3 7.7_25.2 and _1.4 2.6_4.6 , respectively). These time-dependent patterns were not seen with GN-ESRD (IRR _0.4 0.7_1.2 ). Because ESRD in live kidney donors has traditionally been reported in studies averaging <10 years of follow-up, our findings suggest caution in extrapolating such results over much longer intervals.

APOL1-Associated End-Stage Renal Disease in a Living Kidney Transplant Donor

Homozygosity for apolipoprotein-L1 (APOL1) risk variants has emerged as an important predictor of renal disease in individuals of African descent over the past several years. Additionally, these risk variants may be important predictors of renal allograft failure when present in a living or deceased donor. Currently, there is no universal recommendation for screening of potential donors. We present a case of end-stage renal disease with focal segmental glomerulosclerosis in a living donor 7 years following donor nephrectomy. Genetic assessment revealed homozygosity for the G1 high-risk APOL1 variant.

Recipient Outcomes Following Transplantation of Allografts From Live Kidney Donors Who Subsequently Developed End-Stage Renal Disease

Live kidney donors have an increased risk of end-stage renal disease (ESRD) compared with nondonors; however, it is unknown whether undetected, subclinical kidney disease exists at donation that subsequently contributes to this risk. To indirectly test this hypothesis, the authors followed the donated kidneys, by comparing the outcomes of 257 recipients whose donors subsequently developed ESRD with a matched cohort whose donors remained ESRD free. The compared recipients were matched on donor (age, sex, race/ethnicity, donor-recipient relationship), transplant (HLA mismatch, peak panel-reactive antibody, previous transplantation, year of transplantation), and recipient (age, sex, race/ethnicity, body mass index, cause of ESRD, and time on dialysis) risk factors. Median recipient follow-up was 12.5 years (interquartile range 7.4-17.9, maximum 20 years). Recipients of allografts from donors who developed ESRD had increased death-censored graft loss (74% versus 56% at 20 years; adjusted hazard ratio [aHR] 1.7; 95% confidence interval [CI] 1.5-2.0; p < 0.001) and mortality (61% versus 46% at 20 years; aHR 1.5; 95% CI 1.2-1.8; p < 0.001) compared with matched recipients of allografts from donors who did not develop ESRD. This association was similar among related, spousal, and unrelated nonspousal donors. These findings support a novel view of the mechanisms underlying donor ESRD: that of pre-donation kidney disease. However, biopsy data may be required to confirm this hypothesis.

Progress in Transplantation: Will It Be Achieved in Big Steps or by Marginal Gains?

A wish for progress in transplantation assumes that there are needs not met by the currently available therapy and that the barriers to resolving the problems can be surmounted. There are 5 major unmet needs: the potential to avoid transplantation either by prevention of disease or provision of an alternative to natural biological organ replacement; geographic heterogeneity of access to, and quality of, transplantation; availability of transplantation to those in need of it; survival of the patient and the transplant; and the avoidance of adverse effects of immunosuppression. During the past 50 years, there have been advances on at least 4 of these 5 fronts that illustrate the interplay of "big steps" and "marginal gains" in the following areas: surgical technique, testing the immunologic barriers, introduction of chemical and biological immunosuppression, and prophylaxis for microbial infections. The potential for further improvement comes in 5 major areas: blood biomarkers for monitoring of rejection, drug-free transplantation through the development of stable tolerance, eliminating the impact of ischemia-reperfusion injury, xenotransplantation of porcine kidneys, and finally, the possibility of autologous regeneration of functioning kidney tissue to treat advanced kidney disease.

Estimated or Measured GFR in Living Kidney Donors Work-up?

The value of estimated glomerular filtration rate (eGFR) in living kidney donors screening is unclear. A recently published web-based application derived from large cohorts, but not living donors, calculates the probability of a measured GFR (mGFR) lower than a determined threshold. Our objectives were to validate the clinical utility of this tool in a cohort of living donors and to test two other strategies based on chronic kidney disease epidemiology collaboration (CKD-EPI) and on MDRD-eGFR. GFR was measured using ⁵¹ Cr- ethylene-diamine tetraacetic acid urinary clearance in 311 potential living kidney donors (178 women, mean age 50 ± 11.6 years). The web-based tool was used to predict those with mGFR < 80 mL/min/1.73 m² . Inputs to the application were sex, age, ethnicity, and plasma creatinine. In our cohort, a web-based probability of mGFR <90 mL/min/1.73 m² higher than 2% had 100% sensitivity for detection of actual mGFR <80 mL/min/1.73 m² . The positive predictive value was 0.19. A CKD-EPI-eGFR threshold of 104 mL/min/1.73 m² and an MDRD-eGFR threshold of 100 mL/min/1.73 m² had 100% sensitivity to detect donors with actual mGFR <80 mL/min/1.73 m² . We obtained similar results in an external cohort of 354 living donors. We confirm the usefulness of the web-based application to identify potential donors who should benefit from GFR measurement.

Abnormalities in biomarkers of mineral and bone metabolism in kidney donors

Previous studies have suggested that kidney donors may have abnormalities of mineral and bone metabolism typically seen in chronic kidney disease. This may have important implications for the skeletal health of living kidney donors and for our understanding of the pathogenesis of long-term mineral and bone disorders in chronic kidney disease. In this prospective study, 182 of 203 kidney donors and 173 of 201 paired normal controls had markers of mineral and bone metabolism measured before and at 6 and 36 months after donation (ALTOLD Study). Donors had significantly higher serum concentrations of intact parathyroid hormone (24.6% and 19.5%) and fibroblast growth factor-23 (9.5% and 8.4%) at 6 and 36 months, respectively, as compared to healthy controls, and significantly reduced tubular phosphate reabsorption (-7.0% and -5.0%) and serum phosphate concentrations (-6.4% and -2.3%). Serum 1,25-dihydroxyvitamin D3 concentrations were significantly lower (-17.1% and -12.6%), while 25-hydroxyvitamin D (21.4% and 19.4%) concentrations were significantly higher in donors compared to controls. Moreover, significantly higher concentrations of the bone resorption markers, carboxyterminal cross-linking telopeptide of bone collagen (30.1% and 13.8%) and aminoterminal cross-linking telopeptide of bone collagen (14.2% and 13.0%), and the bone formation markers, osteocalcin (26.3% and 2.7%) and procollagen type I N-terminal propeptide (24.3% and 8.9%), were observed in donors. Thus, kidney donation alters serum markers of bone metabolism that could reflect impaired bone health. Additional long-term studies that include assessment of skeletal architecture and integrity are warranted in kidney donors.

Mineral metabolism disturbances in kidney donors: smoke, no fire (yet)

Kasiske and colleagues studied mineral and bone metabolism after unilateral donor nephrectomy. Similar as to what is observed early in the course of chronic kidney disease, fibroblast growth factor 23 and parathyroid hormone concentrations were shown to be increased following kidney donation. High fibroblast growth factor 23 and parathyroid hormone concentrations most probably are a compensatory mechanism to maintain normophosphatemia. Bone biomarker profiles in the study suggest increased bone turnover as trade-off. Limitations inherent to the assessed biomarkers, however, warrant a prudent interpretation.

Long-Term Donor Outcomes after Pure Laparoscopic versus Open Living Donor Nephrectomy: Focus on Pregnancy Rates, Hypertension and Quality of Life

INTRODUCTION

The aim of the present study was to compare long-term donor outcomes after open and laparoscopic living donor nephrectomy. The focus was on pregnancy rates, hypertension and quality of life parameters.

MATERIALS AND METHODS

Data were retrospectively collected using our institution's electronic database and a structured questionnaire. The study included 30 donors after open donor nephrectomy (ODN) and 131 donors after laparoscopic donor nephrectomy (LDN).

RESULTS

Demographic data did not differ between groups. When asked for their preference, significantly more donors in the LDN group would choose the same surgical approach again. The overall frequency of postoperative complications was significantly lower in the LDN group. The incidence of grade III complications was 2% after LDN and 10% after ODN (p = 0.79). Only 2 out of 15 female donors aged between 18 and 45 years delivered a healthy child after DN. On interview, only 4 out of 15 female donors declared the desire to have children after DN.

CONCLUSIONS

From the donor perspective, long-term outcomes after LDN are more favorable than after ODN. To ensure favorable functional outcomes, strict preoperative donor selection and diligent long-term donor follow-up are required.

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

Live kidney donors are exhaustively screened pre-donation, creating a cohort inherently healthier at baseline than the general population. In recent years, three renowned research groups reported unfavourable outcomes for live kidney donors post-donation that contradicted their previous studies. Here, we compared the study design and analysis of the most recent and previous studies to determine whether the different outcomes were due to methodological design or reflect a real potential disadvantage for living kidney donors. All six studies on long-term risk after live kidney donation were thoroughly screened for the selection of study population, controls, data quality, and statistical analysis. Our detailed review of the methodology revealed key differences with respect to selection of donors and compared non-donors, data quality, follow-up duration, and statistical analysis. In all studies, the comparison group of non-donors was healthier than the donors due to more extensive exclusion criteria for non-donors. Five of the studies used both restriction and matching to address potential confounding. Different matching strategies and statistical analyses were used in the more recent studies compared to previous studies and follow-up was longer. Recently published papers still face bias. Strong points compared to initial analyses are the extended follow-up time, large sample sizes and better analysis, hence increasing the reliability to estimate potential risks for living kidney donors on the long-term. Future studies should focus on equal selection criteria for donors and non-donors, and in the analysis, follow-up duration, matched sets, and low absolute risks among donors should be accounted for when choosing the statistical technique.

Long-term trends in the prevalence of chronic kidney disease and the influence of cardiovascular risk factors in Norway

Surveillance of chronic kidney disease (CKD) prevalence over time and information on how changing risk factors influence this trend are needed to evaluate the effects of general practice and public health interventions. Because very few studies addressed this, we studied the total adult population of a demographically stable county representative of Norway using cross-sectional studies 10 years apart (Nord-Trøndelag Health Study (HUNT)2 and Nord-Trøndelag Health Study (HUNT)3, 65,237 and 50,586 participants, respectively). Thorough quality-control procedures and comparisons of methods over time excluded analytical drift, and multiple imputations of missing data combined with nonattendance weights contributed to unbiased estimates. CKD prevalence remained stable in Norway from 1995 through 1997 (11.3%) to 2006 through 2008 (11.1%). The association of survey period with CKD prevalence was modified by a strong decrease in blood pressure, more physical activity, and lower cholesterol levels. Without these improvements, a 2.8, 0.7, and 0.6 percentage points higher CKD prevalence could have been expected, respectively. In contrast, the prevalence of diabetes and obesity increased moderately, but the proportion of diabetic patients with CKD decreased significantly (from 33.4% to 28.6%). A CKD prevalence of 1 percentage point lower would have been expected without these changes. Thus, CKD prevalence remained stable in Norway for more than a decade in association with marked improvements in blood pressure, lipid levels, and physical activity and despite modest increases in diabetes and obesity.

What factors explain the association between socioeconomic deprivation and reduced likelihood of live-donor kidney transplantation? A questionnaire-based pilot case-control study

OBJECTIVES

Socioeconomically deprived individuals with renal disease are less likely to receive a live-donor kidney transplant (LDKT) than less deprived individuals. This study aimed to develop and pilot a questionnaire designed to determine what factors explain this association.

DESIGN

Questionnaire development and a pilot case-control study. Primary aims were to develop and evaluate a questionnaire, assess response rates, and to generate data to inform full-scale study design.

SETTING

A UK tertiary renal referral hospital and transplant centre.

PARTICIPANTS

Invited participants comprised 30 LDKT recipients (cases) and 30 deceased-donor kidney transplant (DDKT) recipients (controls). Stratified random sampling was used to select cases and controls from all adults who had been transplanted at Southmead Hospital North Bristol National Health Service Trust, between 1 August 2007 and 31 July 2013.

METHODS

Participants were posted questionnaires that were accompanied by an invitation letter from the renal consultant responsible for their care, and a patient information leaflet. Non-responders were sent a second questionnaire after 4-6 weeks. Data were extracted from returned questionnaires, and entered onto a Research Electronic Data Capture (REDCap) database.

RESULTS

63% (n=38) of those invited returned questionnaires. 16 (42%) declined to answer the question on income. 58% of participants had not asked any of their potential donors to consider living kidney donation (52% LDKT vs 65% DDKT, p=0.44). There was some evidence of a difference between the R3K-T knowledge score for recipients of LDKTs (mean 6.7, SD 1.8) and for recipients of DDKTs (mean 4.9, SD 2.1), p=0.008. Variables' distribution for the exposure variables of interest was determined.

CONCLUSIONS

Findings from this study will inform a sample size calculation for a full-scale study. The findings of the full-scale case-control study will help us better understand how socioeconomic deprivation is related to the type of transplant an individual receives. This understanding will help us to design and appropriately tailor an intervention to reduce inequitable access to live-donor kidney transplantation.

Glomerular Function and Structure in Living Donors: Lessons from Single Nephron Studies

One third of the kidney transplants performed in the USA come from living kidney donors. The long-term outcome of healthy individuals who donate kidneys is mostly excellent, although recent studies have suggested that living donation is associated with a small absolute increase in the risk of end stage renal failure. Much of our understanding about the progression of kidney disease comes from experimental models of nephron loss. For this reason, living kidney donation has long been of great interest to renal physiologists. This review will summarize the determinants of glomerular filtration and the physiology that underlies post-donation hyperfiltration. We describe the 'remnant kidney' model of kidney disease and the reasons why such progressive kidney disease very rarely ensues in healthy humans following uninephrectomy. We also review some of the methods used to determine glomerular number and size and outline their associations.