The unjustified classification of kidney donors as patients with CKD: critique and recommendations

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.

Risk Factors for Developing Low Estimated Glomerular Filtration Rate and Albuminuria in Living Kidney Donors

Rationale & Objective

Chronic kidney disease is associated with significant morbidity and mortality in the general population, but little is known about the incidence and risk factors associated with developing low estimated glomerular filtration rate (eGFR) and moderate-severe albuminuria in living kidney donors following nephrectomy.

Study Design

Retrospective, population-based cohort study.

Setting & Participants

Kidney donors in Alberta, Canada.

Exposure

Donor nephrectomy between May 2001 and December 2017.

Outcome

Two eGFR measurements <45 mL/min/1.73 m2 or 2 measurements of moderate or severe albuminuria from 1-year postdonation onwards that were at least 90 days apart.

Analytical Approach

Associations between potential risk factors and the primary outcome were assessed using Cox proportional hazard regression analyses.

Results

Over a median follow-up period of 8.6 years (IQR, 4.7-12.6 years), 47 of 590 donors (8.0%) developed sustained low eGFR or moderate-severe albuminuria with an incidence rate of 9.2 per 1,000 person-years (95% confidence interval, 6.6-11.8). The median time for development of this outcome beyond the first year after nephrectomy was 2.9 years (IQR, 1.4-8.0 years). Within the first 4 years of follow-up, a 5 mL/min/1.73 m2 lower predonation eGFR increased the hazard of developing postdonation low eGFR or moderate-severe albuminuria by 26% (adjusted HR, 1.26; 95% CI, 1.10-1.44). Furthermore, donors were at higher risk of developing low eGFR or albuminuria if they had evidence of predonation hypertension (adjusted HR, 2.52; 95% CI, 1.28-4.96) or postdonation diabetes (adjusted HR, 4.72; 95% CI, 1.54-14.50).

Limitations

We lacked data on certain donor characteristics that may affect long-term kidney function, such as race, smoking history, and transplant-related characteristics.

Conclusions

A proportion of kidney donors at an incidence rate of 9.2 per 1,000 person-years will develop low eGFR or albuminuria after donation. Donors with lower predonation eGFR, predonation hypertension, and postdonation diabetes are at increased risk of developing this outcome.

Performance of estimated glomerular filtration rate equations in Black living kidney donor candidates

INTRODUCTION

New estimated glomerular filtration rate (eGFR) equations using serum creatinine and/or cystatin C have been derived to eliminate adjustment by perceived Black ancestry. We sought to analyze the performance of newer eGFR equations among Black living kidney donor candidates.

METHODS

Black candidates (n = 64) who had measured iothalamate GFR between January 2015 and October 2021 were included, and eGFR was calculated using race adjusted (eGFRcr2009 and eGFRcr-cys2012) and race unadjusted (eGFRcys2012, eGFRcr2021, and eGFRcr-cys2021) CKD-EPI equations. Bias and accuracy were calculated.

RESULTS

The eGFRcr2021 equation had a negative bias of 9 mL/min/1.73 m2 , while other equations showed a modest positive bias. Accuracy within 10% and 30% was greatest using the eGFRcr-cys2021 equation. With the eGFRcr2021 equation, 9.4% of donors with an mGFR > 80 mL/min/1.73 m2 were misclassified as having an eGFR < 80 mL/min/1.73 m2 . eGFR was also compared among 18 kidney donors at 6-24 months post-donation. Post-donation, the percentage of donors with an eGFR < 60 mL/min/1.73 m2 was 44% using the eGFRcr2021 equation compared to 11% using the eGFRcr-cys2021 equation.

CONCLUSION

The CKD-EPICr2021 equation appears to underestimate true GFR in Black living donor candidates. Alternatively, compared to CKD-EPICr2021, the CKD-EPICr-CysC2021 equation appears to perform with less bias and improved accuracy.

Bariatric Surgery in Severely Obese Kidney Donors Before Kidney Transplantation: A Retrospective Study

BACKGROUND

Bariatric surgery (BS) is the optimal approach for sustained weight loss and may alter donation candidacy in potential donors with obesity. We evaluated the long-term effects of nephrectomy after BS on metabolic profile, including body mass index, serum lipids and diabetes, and kidney function of donors.

METHODS

This was a single-center retrospective study. Live kidney donors who underwent BS before nephrectomy were matched for age, gender, and body mass index with patients who underwent BS alone and with donors who underwent nephrectomy alone. Estimated glomerular filtration rate (eGFR) was calculated according to Chronic Kidney Disease Epidemiology Collaboration and adjusted to individual body surface area to create absolute eGFR.

RESULTS

Twenty-three patients who underwent BS before kidney donation were matched to 46 controls who underwent BS alone. At the last follow-up, the study group showed significantly worse lipid profile with low-density lipoprotein of 115 ± 25 mg/dL versus the control group with low-density lipoprotein of 99 ± 29 mg/dL ( P  = 0.036) and mean total cholesterol of 191 ± 32 versus 174 ± 33 mg/dL ( P  = 0.046). The second control group of matched nonobese kidney donors (n = 72) had similar serum creatinine, eGFR, and absolute eGFR as the study group before nephrectomy and 1 y after the procedure. At the end of follow-up, the study group had significantly higher absolute eGFR compared with the control group (86 ± 21 versus 76 ± 18 mL/min; P  = 0.02) and similar serum creatinine and eGFR.

CONCLUSIONS

BS before live kidney donation is a safe procedure that could increase the donor pool and improve their health in the long run. Donors should be encouraged to maintain their weight and avoid adverse lipid profile and hyperfiltration.

Living kidney donors with HIV: experience and outcomes from a case series by the HOPE in Action Consortium

Background

Living kidney donation is possible for people living with HIV (PLWH) in the United States within research studies under the HIV Organ Policy Equity (HOPE) Act. There are concerns that donor nephrectomy may have an increased risk of end-stage renal disease (ESRD) in PLWH due to HIV-associated kidney disease and antiretroviral therapy (ART) nephrotoxicity. Here we report the first 3 cases of living kidney donors with HIV under the HOPE Act in the United States.

Methods

Within the HOPE in Action Multicenter Consortium, we conducted a prospective study of living kidney donors with HIV. Pre-donation, we estimated the 9-year cumulative incidence of ESRD, performed genetic testing of apolipoprotein L1 (APOL1), excluding individuals with high-risk variants, and performed pre-donation kidney biopsies (HOPE Act requirement). The primary endpoint was ≥grade 3 nephrectomy-related adverse events (AEs) in year one. Post-donation, we monitored glomerular filtration rate (measured by iohexol/Tc-99m DTPA [mGFR] or estimated with serum creatinine [eGFR]), HIV RNA, CD4 count, and ART.

Findings

There were three donors with two-four years of follow-up: a 35 year-old female, a 52 year-old male, and a 47 year-old male. Pre-donation 9-year estimated cumulative incidence of ESRD was 3.01, 8.01, and 7.76 per 10,000 persons, respectively. In two donors with APOL1 testing, no high-risk variants were detected. Biopsies from all three donors showed no kidney disease. Post-donation, two donors developed nephrectomy-related ≥grade 3 AEs: a medically-managed ileus and a laparoscopically-repaired incisional hernia. GFR declined from 103 to 84 mL/min/1.73 m2 at four years (mGFR) in donor 1, from 77 to 52 mL/min/1.73 m2 at three years (eGFR) in donor 2, and from 65 to 39 mL/min/1.73 m2 at two years (eGFR) in donor 3. HIV RNA remained <20 copies/mL and CD4 count remained stable in all donors.

Interpretation

The first three living kidney donors with HIV under the HOPE Act in the United States have had promising outcomes at two-four years, providing proof-of-concept to support living donation from PLWH to recipients with HIV.

Funding

National Institute of Allergy and Infectious Diseases, National Institutes of Health.

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.

Reclassification of CKD in living kidney donors with the refitted race-free eGFR formula

BACKGROUND

Chronic Kidney Disease (CKD) Epidemiology Collaboration eGFR 2021 formula removed Black race from the 2009 equation. Unintended consequences may lead to reclassifying Black living kidney donors as having more advanced CKD, exacerbating racial disparities in living donation.

METHODS

We used national data to quantify CKD stage reclassification based on eGFR for Black living donors both pre- and post-donation.

RESULTS

Among 6365 Black living donors, 17.7% were reclassified as having a higher CKD stage pre-donation with the 2021 formula. Among 4149 Black living donors with at least 2 creatinine measurements post-donation, 25.5% were reclassified as having a higher CKD stage post-donation with the 2021 formula.

CONCLUSION

Eliminating race in the formula may inappropriately label Black potential donors with CKD. These data highlight the need for a validated eGFR formula for donors, use of measured and not eGFR, and education of non-transplant providers regarding interpretation of CKD staging in living donation.

Novel insights in classic versus relative glomerular hyperfiltration and implications on pharmacotherapy

PURPOSE OF REVIEW

Glomerular filtration rate (GFR) assessment and its estimation (eGFR) is a long-lasting challenge in medicine and public health. Current eGFR formulae are indexed for standardized body surface area (BSA) of 1.73 m2, ignoring persons and populations wherein the ratio of BSA or metabolic rate to nephron number might be different, due to increased BSA, increased metabolic rate or reduced nephron number. These equations are based on creatinine, cystatin C or a combination of the two, which adds another confounder to eGFR assessment. Unusually high GFR values, also known as renal hyperfiltration, have not been well defined under these equations.

RECENT FINDINGS

Special conditions such as solitary kidney in kidney donors, high dietary protein intake, obesity and diabetes are often associated with renal hyperfiltration and amenable to errors in GFR estimation. In all hyperfiltration types, there is an increased intraglomerular pressure that can be physiologic, but its persistence over time is detrimental to glomerulus leading to progressive glomerular damage and renal fibrosis. Hyperfiltration might be underdiagnosed due to BSA standardization embedded in the formula. Hence, timely intervention is delayed. Reducing intraglomerular pressure in diabetes can be achieved by SGLT2 inhibitors or low protein diet to reverse the glomerulopathy process.

SUMMARY

Accurate identification of glomerular hyperfiltration as a pre-CKD condition needs accurate estimation of GFR in the above normal range should establish a threshold for timely intervention.

Recommendations for living donor kidney transplantation

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

Arterial Hypertension as a Risk Factor for Reduced Glomerular Filtration Rate after Living Kidney Donation

Living kidney donation represents the optimal renal replacement therapy, but recent data suggest an increased long-term renal risk for the donor. Here, we evaluated the risk for reduced estimated glomerular filtration rate (eGFR), death, and major cardiovascular events such as nonfatal myocardial infarction or cerebrovascular event including TIA (transient ischemic attack) and stroke in 225 donors, who underwent pre-donation examinations and live donor nephrectomy between 1985 and 2014 at our center. The median follow-up time was 8.7 years (1.0–29.1). In multivariate analysis, age and arterial hypertension at baseline were significantly associated with a higher risk of adverse renal outcomes, such as (1) eGFR <60 mL/min/1.73 m² (age per year: HR (hazard ratio) 1.05, 95% confidence interval (CI) 1.03–1.08, hypertension: HR 2.25, 95% CI 1.22–3.98), (2) eGFR <60 mL/min/1.73 m² and a decrease of ≥40% from baseline (age: HR 1.08, 95% CI 1.03–1.13, hypertension: HR 4.22, 95% CI 1.72–10.36), and (3) eGFR <45 mL/min/1.73 m² (age: HR 1.12, 95% CI 1.05–1.20, hypertension: HR 5.06, 95% CI 1.49–17.22). In addition, eGFR at time of donation (per mL/min/1.73 m²) was associated with a lower risk of (1) eGFR <60 mL/min/1.73 m² (HR 0.98, 95% CI 0.97–1.00) and (2) eGFR <45 mL/min/1.73 m² (HR 0.95, 95% CI 0.90–1.00). Age was the only significant predictor for death or major cardiovascular event (HR 1.08, 95% CI 1.01–1.16). In conclusion, arterial hypertension, lower eGFR, and age at the time of donation are strong predictors for adverse renal outcomes in living kidney donors.

Postdonation eGFR and New-Onset Antihypertensive Medication Use After Living Kidney Donation

Background.

Limited data are available regarding clinical implications of lower renal function after living kidney donation. We examined a novel integrated database to study associations between postdonation estimated glomerular filtration rate (eGFR) and use of antihypertensive medication (AHM) treatment after living kidney donation.

Methods.

Study data were assembled by linking national U.S. transplant registry identifiers, serum creatinine (SCr) values from electronic medical records, and pharmacy fill records for 3222 living donors (1989–2016) without predonation hypertension. Estimated GFR (mL/min per 1.73 m²) was computed from SCr values by the CKD-EPI equation. Repeated measures multivariable mixed effects modeling examined the associations (adjusted odds ratio, _95%LCLaOR_{95% UCL}) between AHM use and postdonation eGFR levels (random effect) with fixed effects for baseline donor factors.

Results.

The linked database identified an average of 3 postdonation SCr values per donor (range: 1–38). Lower postdonation eGFR (vs ≥75) bore graded associations with higher odds of AHM use (eGFR 30–44: aOR _0.951.47_2.26; <30: aOR _1.082.52_5.90). Other independent correlates of postdonation AHM use included older age at donation (aOR per decade: _1.081.23_1.40), black race (aOR _1.031.51_2.21), body mass index > 30 kg/m² (aOR _1.011.45_2.09), first-degree donor–recipient relationship (aOR _1.071.38_1.79), “prehypertension” at donation (systolic blood pressure 120–139: aOR _1.101.46_1.94; diastolic blood pressure 80–89: aOR _1.061.45_1.99).

Conclusions.

This novel linkage illustrates the ability to identify postdonation kidney function and associate it with clinically meaningful outcomes; lower eGFR after living kidney donation is a correlate of AHM treatment requirements. Further work should define relationships of postdonation renal function, hypertension, and other morbidity measures.

Estimated glomerular filtration rate for longitudinal follow-up of living kidney donors

Background

Living kidney donor safety requires reliable long-term follow-up of renal function after donation. The current study aimed to define the precision and accuracy of post-donation estimated glomerular filtration rate (eGFR) slopes compared with measured GFR (mGFR) slopes.

Methods

In 349 donors (age 51 ± 10, 54% female), we analysed eGFR according to the 2009 Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation, Modification of Diet in Renal Disease (MDRD) and Cockcroft-Gault/body surface area (CG/BSA), creatinine clearance (CrCl) and mGFR (125I-iothalamate) changes from 3 months until 5 years post-donation.

Results

Donors had a pre-donation mGFR of 116 ± 23 mL/min, at 3 months post-donation mGFR was 73  ± 14 mL/min and at 5 years it was 79 ± 16 mL/min. Between 3 months and 5 years post-donation, 28% of donors had a declining mGFR (-0.82 ± 0.79 mL/min/year), 47% were stable and 25% had an increasing mGFR. Overall, eGFR equations showed good slope estimates (bias eGFRCKD-EPI 0.13 ± 2.16 mL/min/year, eGFRMDRD 0.19 ± 2.10 mL/min/year, eGFRCG/BSA -0.08 ± 2.06 mL/min/year, CrCl -0.12 ± 4.75 mL/min/year), but in donors with a decreasing mGFR the slope was underestimated (bias eGFRCKD-EPI 1.41 ± 2.03 mL/min/year, eGFRMDRD 1.51 ± 1.96 mL/min/year, eGFRCG/BSA 1.20 ± 1.87 mL/min/year). The CrCl had a high imprecision [bias interquartile range -1.51-3.41 mL/min/year].

Conclusions

All eGFR equations underestimated GFR slopes in donors with a declining GFR between 3 months and 5 years post-donation. This study underlines the value of mGFR in the follow-up of donors with risk of progressive GFR loss.

Larger nephron size, low nephron number, and nephrosclerosis on biopsy as predictors of kidney function after donating a kidney

It is unclear whether structural findings in the kidneys of living kidney donors predict postdonation kidney function. We studied living kidney donors who had a kidney biopsy during donation. Nephron size was measured by glomerular volume, cortex volume per glomerulus, and mean cross-sectional tubular area. Age-specific thresholds were defined for low nephron number (calculated from CT and biopsy measures) and nephrosclerosis (global glomerulosclerosis, interstitial fibrosis/tubular atrophy, and arteriosclerosis). These structural measures were assessed as predictors of postdonation measured GFR, 24-hour urine albumin, and hypertension. Analyses were adjusted for baseline age, gender, body mass index, systolic and diastolic blood pressure, hypertension, measured GFR, urine albumin, living related donor status, and time since donation. Of 2673 donors, 1334 returned for a follow-up visit at a median 4.4 months after donation, with measured GFR <60 mL/min/1.73 m² in 34%, urine albumin >5 mg/24 h in 13%, and hypertension in 5.3%. Larger glomerular volume and interstitial fibrosis/tubular atrophy predicted follow-up measured GFR <60 mL/min/1.73 m² . Larger cortex volume per glomerulus and low nephron number predicted follow-up urine albumin >5 mg/24 h. Arteriosclerosis predicted hypertension. Microstructural findings predict GFR <60 mL/min/1.73 m² , modest increases in urine albumin, and hypertension shortly after kidney donation.

Long-Term Non-End-Stage Renal Disease Risks After Living Kidney Donation

Despite generally positive outcomes and high rates of satisfaction, living kidney donors are at risk for both medical and psychosocial problems. In this review, the authors summarize non-end-stage renal disease (ESRD) risks for donors and describe limitations to the data. We review the evidence of medical risks (e.g. increased cardiovascular disease and mortality, preeclampsia) and psychosocial risks (e.g. mood disturbance, financial burden). We then discuss the evidence of differential risks among subsets and the impact of postdonation events (e.g. development of diabetes). Collectively, available evidence indicates the following. (1) Recognizing the importance of non-ESRD risks has been overshadowed by analyses of the reported risk of ESRD. This imbalance should be remedied. (2) There is little quantification of the true contribution of donation to medical and psychosocial outcomes. (3) Most studies, to date, have been retrospective, with limited sample sizes and diversity and with less-than-ideal controls for comparison of outcomes. (4) Many postdonation events (diabetes and hypertension) can now be reasonably predicted, and their association with adverse outcomes can be quantified. (5) Mechanisms and systems need to be implemented to evaluate and care for donors who develop medical and/or psychosocial problems. (6) Costs to donors are a significant burden, and making donation financially neutral should be a priority.

Interlaboratory Variability in Plasma Creatinine Measurement and the Relation with Estimated Glomerular Filtration Rate and Chronic Kidney Disease Diagnosis

BACKGROUND AND OBJECTIVES

The tracing of creatinine (Cr) reference materials to isotope dilution mass spectrometry-assigned values was implemented worldwide to reduce interlaboratory variability and improve assay accuracy. The aims of this study were to examine the current extent of interlaboratory variability and its effect on eGFR.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Leftover plasma from 2-3 consecutive days was obtained from 53 intensive care unit patients with a range of kidney functions. Individual patient samples were pooled and split and sent to 12 different laboratories for Cr measurement. For each patient, the mean Cr and Chronic Kidney Disease Epidemiology Collaboration eGFR (eGFR-EPI), assuming a 65-year-old nonblack woman, were determined. Interlaboratory variability was assessed by the range and SD of Cr and eGFR-EPI. This was repeated after stratifying by assay type and by the median Cr of 1.36 mg/dl. For patients whose eGFR-EPI range included 60 ml/min per 1.73 m2, the percentage of laboratories with eGFR-EPI<60 ml/min per 1.73 m2 was determined.

RESULTS

The mean±SD of the Cr and eGFR-EPI ranges were 0.20±0.09 mg/dl and 14±9 ml/min per 1.73 m2 for Cr<1.36 mg/dl. Jaffe Cr results were an average 0.1 mg/dl (Cr≥1.36 mg/dl) and 0.05 mg/dl (Cr<1.36 mg/dl) higher than enzymatic results (P<0.001 for both). Ten patients had an eGFR-EPI range that included 60 ml/min per 1.73 m2. Their median eGFR-EPI range was 15 ml/min per 1.73 m2. There was significant discordance in the diagnosis of CKD (eGFR-EPI<60 ml/min per 1.73 m2), with laboratories using Jaffe Cr methods making the diagnosis more frequently than those using enzymatic Cr methods (60% versus 39%).

CONCLUSIONS

Significant interlaboratory variability in Cr measurement still exists. Jaffe assays yield higher Cr values than enzymatic assays, leading to lower eGFR-EPIs and more frequent CKD diagnoses. Further improvements in assay performance are required to standardize patient CKD diagnosis and to facilitate longitudinal Cr monitoring across laboratories.

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

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

Renal Function Profile in White Kidney Donors: The First 4 Decades

Previous studies reported the risk of ESRD after kidney donation, but not the renal outcomes that precede ESRD. Here, we estimated the risk of proteinuria, reduced GFR, and ESRD in 3956 white kidney donors, assessed the contribution of postdonation hypertension and diabetes to these outcomes, and developed a risk calculator. After a mean±SD follow-up of 16.6±11.9 years, 215 (6.1%) donors developed proteinuria. Men had a higher risk of proteinuria (hazard ratio [HR], 1.56; 95% confidence interval [95% CI], 1.18 to 2.05; P<0.001) as did those with higher body mass index (HR, 1.10; 95% CI, 1.06 to 1.13; P<0.001). In all, 1410 (36%) donors reached an eGFR<60 ml/min per 1.73 m(2), and 112 (2.8%) donors had either an eGFR<30 ml/min per 1.73 m(2) or ESRD (28 donors developed ESRD). An eGFR<30 ml/min per 1.73 m(2) or ESRD associated with older age (HR, 1.07; 95% CI, 1.05 to 1.09; P<0.001), higher body mass index (HR, 1.08; 95% CI, 1.04 to 1.13; P<0.001), and higher systolic BP (HR, 1.02; 95% CI, 1.00 to 1.04; P=0.01) at donation. Postdonation diabetes and hypertension associated with a fourfold higher risk of proteinuria and a >2-fold higher risk of ESRD. Models predicting proteinuria and reduced eGFR performed well (C-index 0.77-1.00). In conclusion, severe reduction in GFR and ESRD after kidney donation were uncommon and were highly associated with postdonation diabetes and hypertension. Furthermore, information available before donation may predict long-term renal outcomes in white living kidney donors.

Association of mGFR of the Remaining Kidney Divided by Its Volume before Donation with Functional Gain in mGFR among Living Kidney Donors

BACKGROUND AND OBJECTIVES

The predictors of long-term renal function in living kidney donors are currently discussed. Our objectives were to describe the predictors of functional gain of the remaining kidney after kidney donation. We hypothesized that GFR of the remaining kidney divided by volume of this kidney (rk-GFR/vol) would reflect the density of functional nephrons and be inversely associated with functional gain of the remaining kidney.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We conducted a prospective monocentric study including 63 living donors (26 men; 50.3±11.8 years old) who had been evaluated for (51)Cr-EDTA and measured GFR, split renal function by scintigraphy before donation (between 2004 and 2009), and measured GFR at 5.7±0.5 years after donation. For 52 donors, volume of the remaining kidney (measured and estimated with the ellipsoid formula using renal computed tomography scannography) was determined before donation. We tested our hypothesis in an external validation cohort of 39 living donors (13 men; 51.0±9.4 years old) from another single center during the same time period.

RESULTS

For the main cohort, the mean measured GFR was 97.6±13.0 ml/min per 1.73 m(2) before donation and 63.8±9.4 ml/min per 1.73 m(2) at 5 years. Functional gain averaged 16.2±7.2 ml/min per 1.73 m(2) (+35.3%±16.7%). Multivariate analysis showed that age, body mass index, and rk-GFR/vol at donation were negatively correlated with functional gain and had strong predictive power of the 5-year functional gain (adjusted 5-year functional gain for age: -0.4 [95% confidence interval (95% CI), -0.5 to -0.1]; body mass index: -0.3 [95% CI, -0.6 to -0.1]; rk-GFR/vol: -55.1 [95% CI, -92.3 to -17.9]). We tested this model in the external validation cohort (adjusted 5-year functional gain for age: -0.1 [95% CI, -0.5 to 0.3]; body mass index: -0.9 [95% CI, -1.8 to -0.1]; rk-GFR/vol: -97.6 [95% CI, -137.5 to -57.6]) and confirmed that rk-GFR/vol was inversely associated with 5-year functional gain.

CONCLUSIONS

For given age and body mass index, the long-term functional gain of the remaining kidney is inversely associated with the new variable rk-GFR/vol at donation.

Living-Donor Kidney Transplantation: Reducing Financial Barriers to Live Kidney Donation--Recommendations from a Consensus Conference

Live-donor kidney transplantation (LDKT) is the best treatment for eligible people with late-stage kidney disease. Despite this, living kidney donation rates have declined in the United States in recent years. A potential source of this decline is the financial impact on potential and actual living kidney donors (LKDs). Recent evidence indicates that the economic climate may be associated with the decline in LDKT and that there are nontrivial financial ramifications for some LKDs. In June 2014, the American Society of Transplantation's Live Donor Community of Practice convened a Consensus Conference on Best Practices in Live Kidney Donation. The conference included transplant professionals, patients, and other key stakeholders (with the financial support of 10 other organizations) and sought to identify best practices, knowledge gaps, and opportunities pertaining to living kidney donation. This workgroup was tasked with exploring systemic and financial barriers to living kidney donation. The workgroup reviewed literature that assessed the financial effect of living kidney donation, analyzed employment and insurance factors, discussed international models for addressing direct and indirect costs faced by LKDs, and summarized current available resources. The workgroup developed the following series of recommendations to reduce financial and systemic barriers and achieve financial neutrality for LKDs: (1) allocate resources for standardized reimbursement of LKDs' lost wages and incidental costs; (2) pass legislation to offer employment and insurability protections to LKDs; (3) create an LKD financial toolkit to provide standardized, vetted education to donors and providers about options to maximize donor coverage and minimize financial effect within the current climate; and (4) promote further research to identify systemic barriers to living donation and LDKT to ensure the creation of mitigation strategies.

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.

Gout after living kidney donation: correlations with demographic traits and renal complications

BACKGROUND

The demographic and clinical correlates of gout after living kidney donation are not well described.

METHODS

Using a unique database that integrates national registry identifiers of U.S. living kidney donors (1987-2007) with billing claims from a private health insurer (2000-2007), we identified post-donation gout based on medical diagnosis codes or pharmacy fills for gout therapies. The frequencies and demographic correlates of gout after donation were estimated by Cox regression with left- and right-censoring. We also compared the rates of renal diagnoses among donors with and without gout, matched in the ratio 1:3 by age, sex, and race.

RESULTS

The study sample of 4,650 donors included 13.1% African Americans. By seven years, African Americans were almost twice as likely to develop gout as Caucasian donors (4.4 vs. 2.4%; adjusted hazard ratio, aHR, 1.8; 95% confidence interval (CI) 1.0-3.2). Post-donation gout risk also increased with older age at donation (aHR per year 1.05) and was higher in men (aHR 2.80). Gout rates were similar in donors and age- and sex-matched general non-donors (rate ratio 0.86; 95% CI 0.66-1.13). Compared to matched donors without gout, donors with gout had more frequent renal diagnoses, reaching significance for acute kidney failure (rate ratio 12.5; 95% CI 1.5-107.0), chronic kidney disease (rate ratio 5.0; 95% CI 2.1-11.7), and other disorders of the kidney (rate ratio 2.2; 95% CI 1.2-4.2).

CONCLUSION

Donor subgroups at increased risk of gout include African Americans, older donors, and men. Donors with gout have a higher burden of renal complications after demographic adjustment.

The consequences of chronic kidney disease mislabeling in living kidney donors

Despite numerous studies that substantiate its long-term safety, barriers to kidney donation persist. These include issues of insurability after donation and its consequent financial and emotional burdens. We present 2 cases in which mislabeling of kidney donors as having chronic kidney disease shortly after kidney donation adversely affected their insurability. A concerted effort should be made to affect public policy such that insurability and the psychosocial well-being of living donors are protected.

The Outcomes of Living Kidney Donation from Medically Complex Donors: Implications for the Donor and the Recipient

Living kidney donation is an important option for patients with end-stage renal disease (ESRD), and has improved life expectancy and quality for patients otherwise requiring maintenance dialysis or deceased-donor transplantation. Given the favorable outcomes of live donation and the shortage of organs to transplant, individuals with potentially unfavorable demographic and clinical characteristics are increasingly being permitted to donate kidneys. While this trend has successfully expanded the live donor pool, it has raised concerns as to which acceptance criteria are safe. This review aims to summarize the existing literature on the outcomes of transplantation from medically complex, living kidney donors, including both donor and recipient outcomes when available.

Nutrition assessment and counseling of the medically complex live kidney donor

Kidney transplantation is the preferred option for patients with end-stage renal disease facing the need for dialysis because it provides maximum survival benefit. The number of people seeking kidney transplantation greatly exceeds available deceased donor organs. Organs from live donors provide a survival advantage over organs from deceased donors while also broadening the pool of available organs. The purpose of this review is to discuss the clinical guidelines that pertain to live kidney organ donation and to describe the nutrition evaluation and care of live kidney donors. The process for living kidney donation is dictated by policies centered on protecting the donor. In a perfect world, the living donor would present with a flawless medical examination and a benign family health history. The obesity epidemic has emerged as a major health concern. Live donor programs are faced with evaluating increasing numbers of obese candidates. These "medically complex donors" may present with obesity and its associated comorbid conditions, including hypertension, impaired glycemic control, and kidney stone disease. The dietitian's role in the live donor program is not well defined. Participation in the living donor selection meeting, where details of the evaluation are summarized, provides a platform for risk stratification and identification of donors who are at increased lifetime risk for poor personal health outcomes. Guiding the donor toward maintenance of a healthy weight through diet and lifestyle choices is a legitimate goal to minimize future health risks.

Transplantation: Increased ESRD and mortality risk for kidney donors?

For most patients with end-stage renal disease (ESRD), a kidney transplant is the best treatment option. Compared with dialysis, a successful kidney transplant is associated with increased life expectancy and improved quality of life; a living donor transplant is associated with better long-term results than a deceased donor transplant.