Proteinuria and reduced kidney function in living kidney donors: A systematic review, meta-analysis, and meta-regression

Overall and cardiovascular mortality in Norwegian kidney donors compared to the background population

BACKGROUND

There are concerns regarding potential long-term risks to the living kidney donor. Cardiovascular mortality has not been evaluated. The aim of this study was to assess overall and cardiovascular mortality in previous kidney donors compared with a general population sample.

METHODS

All live kidney donors in Norway in the period 1963-2007 were included. Controls matched 3:1 for age, gender and year of birth were provided by Statistics, Norway. Cause of death was retrieved from the death master file. Vital status as of 1 January 2010 was provided for all participants, and cause of death was available until 1 January 2008. Comparative survival analyses were performed by Kaplan-Meier curves and log-rank test. Age-stratified death rates were calculated and compared with a selected group with a health status hypothetically allowing donation.

RESULTS

There were 2269 living kidney donors in the study period. At donation, mean age was 47.6 + 12.6 years, 41.3% were male. Median observation time was 14.3 years. A total of 324 donors died during the study period. Causes of death were similar for donors and controls. By Kaplan-Meier analysis, overall and cardiovascular mortality was lower for previous kidney donors than for matched controls (P < 0.001 and P = 0.004, respectively). Age-stratified death rates were elevated for the oldest group of donors.

CONCLUSIONS

Overall and cardiovascular mortality results are partially reassuring. However, the seemingly elevated mortality rate among the oldest donors requires further study.

Screening and follow-up of living kidney donors: a systematic review of clinical practice guidelines

To minimize the health risks faced by living kidney donors, multiple clinical practice guidelines have been developed on the assessment and care of potential donors. This study aims to compare the quality, scope, and consistency of these guidelines. We searched for guidelines on living kidney donation in electronic databases, guideline registries, and relevant Web sites to February 21, 2011. Methodological quality was assessed using the Appraisal of Guidelines for Research and Education (AGREE) instrument. Textual synthesis was used to compare guideline recommendations. Ten guidelines, published from 1996 to 2010, were identified. Although generally comprehensive, scope varied considerably and mostly appeared to lack methodological rigor. Many recommendations were consistent, but important differences were evident, particularly for thresholds for comorbidities which precluded donation; obesity/overweight (body mass index, 30-35 kg/m), diabetes/prediabetes (fasting blood glucose level, 6.1-7.0 mmol/L and oral glucose tolerance test, 7.8-11.1 mmol/L), hypertension (130/85 to 140/90 mm Hg), cardiovascular disease, malignancy, and nephrolithiasis. The importance of informed voluntary consent, genuine motivation, support, and psychological health were recognized but difficult to implement as specific tools for conducting psychosocial assessments were not recommended. Multiple major guidelines for living kidney donation have been published recently, resulting in unnecessary duplicative efforts. Most do not meet standard processes for development, and important recommendations about thresholds for exclusion based on comorbidities are contradictory. There is an urgent need for international collaboration and coordination to ensure, where possible, that guidelines for living donation are consistent, evidence based, and comprehensive to promote best outcomes for a precious resource.

When good intentions are not enough: obtaining follow-up data in living kidney donors

The Organ Procurement Transplant Network/United Network for Organ Sharing (OPTN/UNOS) has increased the amount of data collected before and after donation and increased the duration of donor follow-up to 2 years, yet there is evidence that reporting is incomplete. We examined the frequency of missing data in the OPTN/UNOS donor follow-up registry and found that reporting rates were low, particularly for donors who may have limited access to health care. We argue that a national donor follow-up registry is essential to ensure transparency in ascertaining long-term health outcomes among all living donors and in providing assessments of quality assurance within transplant programs. We have suggested approaches to strengthen the donor follow-up registry system. These include setting clear and high standards for follow-up reporting, a system of incentives and penalties that would motivate transplant centers to comply with these standards and would encourage donors to follow-up and lifelong follow-up reporting by primary care providers. We argue that the US government must provide funding to support a donor follow-up registry that can allow for meaningful and valid conclusions, in recognition of donors' public service and to maintain trust in the system of living organ donation.

Lack of health insurance in living kidney donors

Living donors are recommended to receive lifelong routine health maintenance after donation. There has been little examination of health insurance status among living donors, despite the fact that lack of health insurance is likely to impede donors' ability to obtain long-term healthcare post-donation. We performed a retrospective chart review for all living kidney donors at our institution between 2004 and 2008 to determine insurance status, demographic, socioeconomic, and basic health characteristics. Twenty-three percent of donors were uninsured at the time of donation. Odds of being uninsured were significantly lower in donors who were older than 40 yr of age or who had at least a college education, and significantly higher in donors who were non-white, non-English-speaking, or non-US citizens. Odds of being uninsured did not differ according to whether donors were obese, hypertensive, or smokers. On multivariate analysis, only non-white race, non-US citizenship, and education level less than a college degree were associated with lack of insurance. Lack of health insurance is more prevalent in living kidney donors than in the general US population. Its disproportionate impact on minorities, non-citizens, and the less well educated is greater than that in the general population.

Age, gender, and body mass index are associated with renal function after kidney donation

Renal function is thoroughly evaluated before live kidney donation. However, some donors experience impaired recovery of renal function after donation. Our aim was to assess estimated glomerular filtration rate (eGFR) and mean relative (%) increase in creatinine one yr after donor nephrectomy. The study was based on retrospective data from kidney donors during the period 1997-2009. Pre-operative and one-yr follow-up data were available for 721 of 1067 donors. Mean relative increase in creatinine and eGFR were stratified by gender, body mass index (BMI), and age at donation. At one yr post-donation, overweight (BMI > 5 kg/m(2) ) women 50 yr or older experienced the lowest eGFR of 49.6 ± 8.8 mL/min/1.73 m(2) . Men younger than 50 yr with normal weight (BMI < 25 kg/m(2) ) had the highest eGFR of 66.6 ± 10.4 mL/min/1.73 m(2) . Overweight men 50 yr or older had the highest relative increase in creatinine of 49.4% compared to pre-donation. Men under 50 yr with normal weight had the smallest increase in creatinine of 35.2%. In multivariate analysis, older age (p < 0.001), male gender (p < 0.001), and overweight (p = 0.01) were associated with relative increase in creatinine after donation. Potential donors should be offered counseling regarding overweight, as this is a modifiable risk factor.

Residual renal function after partial or radical nephrectomy for renal cell carcinoma

Renal cell carcinoma (RCC) is often detected incidentally and early. Currently, open partial nephrectomy and laparoscopic total nephrectomy form competing technologies. The former is invasive, but nephron-sparing; the other is considered less invasive but with more loss of renal mass. Traditionally, emphasis has been placed on oncologic outcomes. However, a patient with an excellent oncologic outcome may suffer from morbidity and mortality related to renal failure. Animal models with hypertension and diabetic renal disease indicate accelerated progression of pre-existing disease after nephrectomy. Patients with RCC are older and they have a high prevalence of diabetes and hypertension. The progression of renal failure may also be accelerated after a nephrectomy. Our analysis of the available literature indicates that renal outcomes in RCC patients after surgery are relatively poorly defined. A strategy to systematically evaluate the renal function of patients with RCC, with joint discussion between the nephrologist and the oncologic team, is strongly advocated.

Understanding the effects of chronic kidney disease on cardiovascular risk: are there lessons to be learnt from healthy kidney donors?

Chronic kidney disease (CKD) is now a recognized global public health problem. It is highly prevalent and strongly associated with hypertension and cardiovascular disease (CVD); far more patients with a glomerular filtration rate below 60 ml min(-1) per 1.73 m(2) will die from cardiovascular causes than progress to end-stage renal disease. A better understanding of the complex mechanisms underlying the development of CVD among CKD patients is required if we are to begin devising therapy to prevent or reverse this process. Observational studies of CVD in CKD are difficult to interpret because renal impairment is almost always accompanied by confounding factors. These include the underlying disease process itself (for example, diabetes mellitus and systemic vasculitis) and the complications of CKD, such as hypertension, anaemia and inflammation. Kidney donors provide an ideal opportunity to study healthy subjects without manifest vascular disease who experience an acute change from having normal to modestly impaired renal function at the time of uninephrectomy. Prospectively examining the cardiovascular consequences of uninephrectomy using donors as a model of CKD may provide useful insight into the pathophysiology of CVD in CKD and, therefore, into how the CVD risk associated with renal impairment might eventually be reduced.

Post-nephrectomy development of renal function in living kidney donors: a cross-sectional retrospective study

BACKGROUND

Increasing numbers of living donor kidney transplantations calls for better knowledge about long-term donor outcomes and risks.

METHODS

To explore long-term kidney donor outcomes and risks, we conducted a cross sectional retrospective study. To this end, we analysed renal function using measured glomerular filtration rate (mGFR) and estimated glomerular filtration rate (eGFR) as well as microalbuminuria, blood pressure (BP), body mass index, haemoglobin, albumin and parathyroid hormone in kidney donors nephrectomized between 1965 and 2005.

RESULTS

A total number of 573 kidney donors agreed to undergo medical follow-up examinations. The mean age (standard deviation) at donation was 47 (11) years and the mean time since donation was 14 (9) years. Both mean mGFR [68 (15) mL/min/1.73 m(2) body surface; P = 0.028] and mean eGFR [71 (16) mL/min/1.73 m(2) body surface; P < 0.001], based on modified diet renal dysfunction and iohexol or Cr-EDTA clearance, respectively, were found to decrease with age and to increase with time since donation. Special multivariable regression analyses reveal that for 30-year old donors, the median eGFR typically increases during the first 17 years, then remains constant for ~8 years and slowly declines thereafter. For 50-year-old donors, the median eGFR is expected to increase during the first 15 years or so and then to enter a phase of slight progressive decline. In total, 23% (126/546) of the donors were on antihypertensive medication. An additional 22% (117/543) of the donors were found to suffer from hitherto undiagnosed hypertension (BP >140/90 mm Hg).

CONCLUSION

Renal function of the remaining kidney in living donors is expected to improve for many years but will show signs of slight deterioration in the longer run.

Impact of Kidney Disease Outcomes Quality Initiative guidelines on the prevalence of chronic kidney disease after living donor nephrectomy

PURPOSE

We evaluated the prevalence of chronic kidney disease stage 3 or worse based on the National Kidney Foundation Kidney Disease Outcomes Quality Initiative guidelines after living kidney donation at a single institution.

MATERIALS AND METHODS

The collected data of 86 consecutive patients who underwent uneventful donor nephrectomy between 1987 and 2008 were evaluated retrospectively. Estimated glomerular filtration rate was determined using the Modification of Diet in Renal Disease from serum creatinine levels collected before and after surgery in kidney donor followup clinics. Chronic kidney disease was defined as an estimated glomerular filtration rate of less than 60 ml/minute/1.73 m(2) according to the Kidney Disease Outcomes Quality Initiative guidelines. Cox regression analyses were then used to determine the impact of predictors on the development of chronic kidney disease.

RESULTS

All donors (mean age 41.2, SD 9.9 years) had a mean preoperative estimated glomerular filtration rate of 88.7 ml/min/1.73 m(2) (SD 16.3). Median followup was 6.4 years (range 0.9 to 21.0). Progression to stage 3 or worse chronic kidney disease was seen in 24.4% (95% CI 15.2-33.7) of patients. There were 2 patient deaths secondary to cancer and none required dialysis. Multivariable analysis showed that preoperative estimated glomerular filtration rate less than 82 ml/minute/1.73 m(2) was an independent risk factor for post-donation chronic kidney disease. For every 1 ml/minute/1.73 m(2) increase in baseline estimated glomerular filtration rate, the hazard of postoperative chronic kidney disease was reduced by 7% (HR 0.93, 95% CI 0.89-0.97, p = 0.001).

CONCLUSIONS

Kidney Disease Outcomes Quality Initiative stage 3 chronic kidney disease or worse occurs in 24.4% of kidney donors. Long-term prospective studies and closer followup of donors are needed to identify its implications, given the associated risk of cardiovascular diseases with chronic kidney disease in the general population.

Clinical analysis of living related renal transplantation with donors older than 50 years in China

OBJECTIVE

The objective of this study was to investigate whether kidney grafts from living related donors older than 50 years were safe for the donors and recipients in the long term.

METHODS

One hundred seven living related donor kidney transplantations were performed in our center from April 1994 to December 2007. No prisoners or organs from prisoners were used in the collection of these data. Donors were divided into 2 groups: >50 years of age (range, 51-78 years), designated as the study group, and ≤50 years of age (range, 21-50 years), designated as the control groups. The mean time of follow-up was 49 months (range, 12-180 months). Clinical data were compared, including donor serum creatinine (Scr) levels, glomerular filtration rates (GFR) before and after the procedures operative complications, and postoperative short-term and long-term recovery of renal function in recipients as well as their complications and recipient and kidney survivals.

RESULTS

All operations were successfully performed. Before the operation, the mean Scr and GFR were 82.16 ± 10.86 umol/L and 85.82 ± 6.26 mL/min, respectively, in the study group versus 78.66 ± 10.41 umol/L and 88.74 ± 9.44 mL/min, respectively, in the control group. There were no significant differences in mean Scr or GFR values between the groups at various preoperative or postoperative times (P > .05). No severe perioperative complications occurred, and no subsequent renal function failure was observed upon long-term follow-up of donors in the 2 groups. Comparisons of recipient age, gender ratio, duration on dialysis, HLA matches, cold/warm ischemia times, and immunosuppression therapy showed a correlations between the 2 groups. Mean Scr levels of recipients, which were compared from 1 week to 3 years following surgery, were slightly higher among the control than the study group, but the difference was not significant (P > .05). There were no significant differences between the study and control groups in 1-,3-,5-, and 8-year recipient/graft survival rates (P > .05).

CONCLUSIONS

Long-term follow-up showed that transplantations using grafts from donors older than 50 years of age yielded similar results to those with younger donors.

Short- and long-term outcomes of living donors in Tunisia: a retrospective study

Despite initiatives to increase cadaveric donation, there is still a shortfall in donor organs. Kidneys from living donors now makes a significant contribution to increasing the number of organs available for transplantation in Tunisia. We performed a retrospective study of 405 kidney transplantations, including 321 (79.3%) from living donors performed from June 1986 to December 2007. We obtained information on only 162 (50.4%), namely, 64 men (39.5%) and 98 women (60.5%), whose mean age at the time of donation was 42.3 ± 12.2 years. Twelve (8.22%) perioperative complications occurred: wound infections (n = 4), pneumothorax (n = 4), phlebitis (n = 1), hematomas (n = 2), and urinary infection (n = 1). The mean follow-up period was 117.4 ± 74.4 months. Hypertension occurred in 42 donors (25.9%) with mean values of 134 ± 20 for systolic and 79 ± 10 for diastolic blood pressure. Twelve donors (7.4%) developed proteinuria (mean proteinuria, 0.08 ± 1.25 g/d). Renal insufficiency was found in 28 donors (19.44%), 2 of whom developed chronic renal failure requiring dialysis at intervals of 36 and 84 months. In both cases, we diagnosed a familial form of focal segmental glomerulosclerosis. Two donors (1.2%) died within 10 years after kidney donation due to senility. The relatively favorable outcomes suggest that living-donor kidney transplantation is an acceptable approach, in view of the superior results it yields in recipients. However, efforts to increase the number of cadaveric donors in Tunisia should be made. It is also important to develop a registry of long-term kidney function after kidney donation.

Reduced glomerular filtration rate due to loss of nephron mass may be an independent risk factor for atherosclerosis

BACKGROUND

Whether living with reduced nephron mass (RNM) poses a risk to humans is the subject of ongoing controversy. The aim of this study was to discover whether or not RNMs are associated with greater atherosclerotic plaque burdens.

METHODS

Using the post-operative abdominal CT scans of 739 nephrectomized patients [NP; 315 women and 424 men; mean age 64.5 ± 15.0 years; observation period 4.9 ± 5.7 years (3675.9 patient-years)] and of an age- and a gender-matched control group, a retrospective observational and case-control study was conducted. The V600 calcium scoring method was used to determine the aortic calcium volume score (ACS) and thus the APB.

RESULTS

The ACS was 0.47 ± 0.77 mm(3) in the NPs compared with 0.41 ± 0.69 mm(3) in the control group (P <0.0001). The ACS and the glomerular filtration rate (GFR using the CKD-EPI formula) after nephrectomy correlated inversely (P = - 0.3652; P <0.0001), and the ACS and the time since nephrectomy correlated positively (P = 0.2919; P <0.0001). In linear regression models, age, time interval and GFR after nephrectomy proved to be independent factors of influence on ACS (P <0.05 each). Including the control group, age, GFR after nephrectomy and nephrectomy were independent factors of influence on the ACS. The factor GFR after nephrectomy explains ~ 10.7% in NPs, and 28% of the variance of the ACS in all patients.

CONCLUSIONS

The factors 'low GFR' and RNM are risk factors for greater atherosclerotic plaque burden. Patients with RNM should undergo regular control examinations to monitor arterial blood pressure and treat hypertension if it occurs.

Barriers to living donor kidney transplantation among black or older transplant candidates

BACKGROUND AND OBJECTIVES

Lower rates of living donor kidney transplant (LDKT) among transplant candidates who are black or older may stem from lower likelihoods of (1) recruiting potential living donors or (2) potential donors actually donating (donor "conversion").

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

A single-center, retrospective cohort study was performed to determine race, age, and gender differences in LDKT, donor recruitment, and donor conversion.

RESULTS

Of 1617 kidney transplant candidates, 791 (48.9%) recruited at least one potential living donor, and 452 (28.0%) received LDKTs. Black transplant candidates, versus non-blacks, were less likely to receive LDKTs (20.5% versus 30.6%, relative risk [RR] = 0.67), recruit potential living donors (43.9% versus 50.7%, RR = 0.86), and receive LDKTs if they had potential donors (46.8% versus 60.3%, RR = 0.78). Transplant candidates ≥60 years, versus candidates 18 to <40 years old, were less likely to receive LDKTs (15.1% versus 43.2%, RR = 0.35), recruit potential living donors (34.0% versus 64.6%, RR = 0.53), and receive LDKTs if they had potential donors (44.5% versus 66.8%, RR = 0.67). LDKT and donor recruitment did not differ by gender. Race and age differences persisted in multivariable logistic regression models. Among 339 candidates who recruited potential donors but did not receive LDKTs, blacks (versus non-blacks) were more likely to have potential donors who failed to donate because of a donor-related reason (86.9% versus 72.5%).

CONCLUSIONS

Black or older kidney transplant candidates were less likely to receive LDKTs because of lower likelihoods of donor recruitment and donor conversion.

Race and renal function early after live kidney donation: an analysis of the United States Organ Procurement and Transplantation Network Database

Among Americans, the risk for kidney disease is higher in individuals of African descent (AA) when compared with Caucasians. We considered whether there are similar racial differences in kidney function soon after donor nephrectomy. Of the 31,928 live kidney donors that donated between the years 2000 and 2005, 16,996 (53%) had post-donation serum creatinine recorded at a mean follow-up of 156 d (range 1-1410 d). A total of 14,525 (85%) were Caucasians and 2471 (15%) were AA. When compared with Caucasians, AA donors were more likely to be younger, heavier, and male, had a higher baseline serum creatinine and a shorter duration of follow-up. After accounting for these differences, the serum creatinine after donation and fractional rise in serum creatinine after donation were similar between the two groups (AA vs. Caucasian donors, 1.3 ± 0.3 vs. 1.2 ± 0.3 mg/dL; 53% vs. 45%) and the post-donation estimated glomerular filtration rate was also similar (57.2 ± 0.6 vs. 56.0 ± 0.2 mL/min per 1.73 m(2)). We observed no major clinical difference in glomerular filtration rate and ability to compensate for loss of renal mass soon after live kidney donation between Caucasian and AA donors.

Relationship between renal parenchymal volume and single kidney glomerular filtration rate before and after unilateral nephrectomy

OBJECTIVES

To measure the renal parenchymal volume (RPV) before and after unilateral nephrectomy and investigate the relationship between the RPV and single kidney glomerular filtration rate (GFR).

METHODS

From November 2003 to August 2009, 183 patients who had undergone unilateral nephrectomy were enrolled in the present study. All patients had undergone preoperative technetium-99m dimercaptosuccinic acid renal scintigraphy. Contrast-enhanced computed tomography was performed before and 6 months after surgery. RPV was calculated as the normally functioning tissue, excluding tumors or nonenhanced areas, using a 3-dimensional image reconstruction program.

RESULTS

The mean split GFR of the remaining kidney increased by 21.2%, from 41.6 to 49.5 mL/min/1.73 m(2) at 6 months after nephrectomy. The mean RPV of the remaining kidney increased by 9.3%, from 164.2 to 178.8 cm(3) after nephrectomy. The preoperative relative RPV of the remaining kidney was 58.8% (range 37.2%-97.9%) and the technetium-99m dimercaptosuccinic acid uptake was 62.2% (range 39.6%-100%), indicating a significant linear correlation (R = 0.865, P <.001). RPV correlated well with the single kidney GFR and patient age, both preoperatively and postoperatively. The postoperative GFR could be predicted by combining the preoperative factors. Multivariate regression analysis revealed that the RPV was positively associated with the single kidney GFR and negatively associated with patient age.

CONCLUSIONS

The differential renal function correlated well with the RPV and can be estimated by calculating the RPV. Even without using renal scintigraphy, the postoperative GFR can be predicted using our established formula.

Long-term outcomes of kidney donors

PURPOSE OF REVIEW

Partial renal ablation in laboratory animals leads initially to compensatory glomerular hyperfiltration and progressive, sclerotic kidney disease. In addition, modest declines in kidney function are associated with premature mortality in epidemiological studies. Hence, the long-term safety of living-kidney donation is an important issue. The purpose of this review was to examine existing research on outcomes among living-kidney transplant donors, with a focus on longer term outcomes.

RECENT FINDINGS

Although studies with sibling controls are unavailable, the current evidence base suggests that kidney donors have mortality and end-stage renal disease risks that are equivalent to similar individuals in the general population. Although findings for albuminuria and hypertension vary between studies, risks may be acceptable if donors receive optimal follow-up and care. Parenthetically, viewed as an experimental model of kidney-function loss, the neutrality of outcomes among donors may have major implications for the population at large: the robust associations between modest declines in kidney function and mortality seen in the general population suggest a confounded relationship and finding these confounders could have major implications for future research directions and for public health.

SUMMARY

Long-term outcomes suggest that kidney donation is not a major threat to longevity.

Health insurance status of US living kidney donors

BACKGROUND AND OBJECTIVES

Ensuring follow-up of living kidney donors (LKDs) is essential to long-term preventive care. We sought information on health insurance status of US LKDs, with particular attention to age, gender, and ethnicity.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

The United Network for Organ Sharing/Organ Procurement Transplantation Network database was queried for associations among age at donation, race, gender, and health insurance status. We studied all US LKDs between July 2004 and September 2006.

RESULTS

A total of 10,021 LKDs with known health insurance status were studied, 1765 (18%) of whom lacked health insurance at donation. There were 4852 donors without health insurance information. Younger kidney donors had higher rates of being uninsured (age 18 to 34: 26.2%; age 35 to 49: 15.2%; age 50 to 64: 11.2%; age >65: 3.8%; P < 0.0001), as did men (19.5 versus 16.3% for women; P < 0.0001), and ethnic minorities (white 13.4%, black 21%, Hispanic 35.6%, Asian 26.7%; P < 0.0001).

CONCLUSIONS

This study confirms that younger patients, ethnic minorities, and men are less likely to have health insurance when donating a kidney, which could negatively affect adherence to long-term follow-up.

Diabetes after kidney donation

Kidney donors, similar to the general population, are at risk for development of type 2 diabetes mellitus (T2DM). The course of donors who develop T2DM has not been studied. We surveyed 3777 kidney donors regarding the development of T2DM. Of the 2954 who responded, 154 developed T2DM 17.7 +/- 9.0 years after donation. The multivariable risk of development of T2DM was associated with type 1 DM in the recipient, male gender and body mass index >30 kg/m(2) at time of donation. Compared to age, gender, duration after donation and body mass index (BMI)-matched non-diabetic donor controls; diabetic donors were more likely to have hypertension (70.8% vs. 36.2%, p = 0.005), proteinuria (18.8% vs. 3.9%, p < 0.0001) but had a similar serum creatinine. eGFR change after T2DM development was -0.80 +/- 0.94 mL/min/year, -0.70 +/- 0.86 in nondiabetic donors with similar duration after donation and -0.61 +/- 0.76 mL/min/year in age, gender, BMI and duration after donation matched nondiabetic donor controls. These preliminary and short-term data demonstrate that factors associated with T2DM in kidney donors are similar to those in the general population and donors screened carefully at the time of donation do not appear to have an acceleration of diabetic kidney disease.

Compensatory changes in the function of the remaining kidney immediately after unilateral nephrectomy in sheep

Live kidney donation is an established form of organ donation but carries the risk of an unnecessary surgery in a normal individual for the benefit of the recipient. Despite a number of recent studies on the renal function of long-term kidney donors, little attention has been paid to the damaging effects of compensatory hyper-filtration on renal tubular cells immediately after donor nephrectomy. The present study therefore aimed to examine the immediate changes in renal function of the remaining kidney using a sheep model of unilateral nephrectomy. We used the gamma camera-based method to measure the glomerular filtration rate and the tubular excretion values after simultaneous injection of (99m)Tc-diethylene triamine pentaacetic acid and (131)I-ortho-iodohippurate tracers. Compared were the differences in the functions between the remaining left kidney immediately after clamping the right renal pedicle and the baseline values that were measured one week before unilateral nephrectomy. After radionuclide data acquisition was completed, the right kidney was removed. The mean glomerular filtration rate (GFR) increased by 52.3% from the baseline values (29.5 +/- 2.7 to 45.0 +/- 6.7 ml/min; n = 40, p < 0.001), while the mean effective renal plasma flow (ERPF) increased by 40% (225.5 +/- 27.8 to 357.8 +/- 38.94 ml/min; p < 0.001), respectively. Mean filtration fraction was increased from 0.117 to 0.127 immediately after nephrectomy (p < 0.001). We conclude that after unilateral nephrectomy the remaining kidney immediately compensates for the loss of a donated kidney by increasing glomerular filtration rate and effective renal plasma flow.

Is living kidney donation the answer to the economic problem of end-stage renal disease?

The escalating number and cost of treating patients with end-stage renal disease is a considerable economic concern for health care systems and societies globally. Compared with dialysis, kidney transplantation leads to improved patient survival and quality of life, as well as cost savings to the health payer. Despite efforts to increase kidney transplantation, the gap between supply and demand continues to grow. In this article we explore the economic consideration of both living and deceased transplantation. Although living kidney donation has several advantages from an economic perspective, efforts to increase both deceased and living donation are required. Strategies to increase kidney donation are underfunded, and even costly strategies are likely to lead to net health care savings. However, demonstration of efficacy of these strategies is required to ensure efficient use of resources.

How do living kidney donors develop end-stage renal disease?

The clinical course and risk factors for developing end-stage renal disease (ESRD) after heminephrectomy in living kidney donors have scarcely been investigated. We reviewed medical records and identified eight case donors who developed chronic kidney disease (CKD) stage 5 or ESRD, and subsequently investigated the association between postoperative clinical courses and changes in renal function. To conduct a case-control study, we also selected a control group comprising 24 donors who had maintained stable renal function and were matched for age, sex and follow-up time since donation. Except for one donor who developed ESRD caused by a traffic accident, none of the donors developed progressive renal dysfunction immediately after donation. Their renal functions remained stable for a long period of time, but started to decline after developing new comorbidities, especially risk factors known as progression factors (proteinuria or hypertension) or accelerating factors (cardiovascular [CV] event or infection) of CKD. As compared with the control donors, incidence of postoperative persistent proteinuria, acute CV event, severe infection and hospitalization due to accelerating factors of CKD were significantly higher in the case donors. These results suggest the importance of long-term (more than 10 years) follow-up of donors with special attention on the risk factors of CKD.

The science of Stewardship: due diligence for kidney donors and kidney function in living kidney donation--evaluation, determinants, and implications for outcomes

Living kidney donor transplantation is now a common treatment for ESRD because it provides excellent outcomes to transplant recipients and is considered a safe procedure for prospective donors. The short- and long-term safety of prospective donors is paramount to the continued success of this procedure. Whereas the initial experiences with living kidney donors mostly included the healthiest, the increase in the need for organs and the changing demographic characteristics of the general population have subtly reshaped the suitability for donation. Kidney function assessment is a critical component of the evaluation of prospective donors; therefore, special emphasis is usually placed on this aspect of the evaluation. At the same time, consideration of kidney function after donation is important because it assists with the determination of renal health in donors. This review summarizes the process of predonation kidney function assessment, determinants of pre- and postdonation renal function, and, importantly, the potential implications of kidney function to the long-term outcomes of kidney donors.

Life insurance for living kidney donors: a Canadian undercover investigation

Some living kidney donors encounter difficulties obtaining life insurance, despite previous surveys of insurance companies reporting otherwise. To better understand the effect of donation on insurability, we contacted offices of life insurance companies in five major cities in Canada to obtain $100 000 of life insurance (20-year term) for 40 fictitious living kidney donors and 40 paired controls. These profiles were matched on age, gender, family history of kidney disease and presence of hypertension. The companies were blinded to data collection. The study protocol was reviewed by the Office of Research Ethics. The main study outcomes were the annual premium quoted and total time spent on the phone with the insurance agent. All donor and control profiles received a quote, with no significant difference in the premium quoted (medians $190 vs. $209, p = 0.89). More time was spent on the phone for donor compared to control profiles, but the absolute difference was small (medians 9.5 vs. 7.0 min, p = 0.046). Age, gender, family history of kidney disease and new-onset hypertension had no further effect on donor insurability in regression analysis. We found no evidence that kidney donors were disadvantaged in the first step of applying for life insurance. The effect donation has on subsequent phases of insurance underwriting remains to be studied.

Demographic and clinical characteristics associated with glomerular filtration rates in living kidney donors

Due to the shortage of organs, living donor acceptance criteria are becoming less stringent. An accurate determination of the glomerular filtration rate (GFR) is critical in the evaluation of living kidney donors and a value exceeding 80 ml/min per 1.73 m(2) is usually considered suitable. To improve strategies for kidney donor screening, an understanding of factors that affect GFR is needed. Here we studied the relationships between donor GFR measured by (125)I-iothalamate clearances (mGFR) and age, gender, race, and decade of care in living kidney donors evaluated at the Cleveland Clinic from 1972 to 2005. We report the normal reference ranges for 1057 prospective donors (56% female, 11% African American). Females had slightly higher mGFR than males after adjustment for body surface area, but there were no differences due to race. The lower limit of normal for donors (5th percentile) was less than 80 ml/min per 1.73 m(2) for females over age 45 and for males over age 40. We found a significant doubling in the rate of GFR decline in donors over age 45 as compared to younger donors. The age of the donors and body mass index increased over time, but their mGFR, adjusted for body surface area, significantly declined by 1.49+/-0.61 ml/min per 1.73 m(2) per decade of testing. Our study shows that age and gender are important factors determining normal GFR in living kidney donors.

Pregnancy and birth after kidney donation: the Norwegian experience

Reports on pregnancies in kidney donors are scarce. The aim was to assess pregnancy outcomes for previous donors nationwide. The Medical Birth Registry of Norway holds records of births since 1967. Linkage with the Norwegian Renal Registry provided data on pregnancies of kidney donors 1967-2002. A random sample from the Medical Birth Registry was control group, as was pregnancies in kidney donors prior to donation. Differences between groups were assessed by two-sided Fisher's exact tests and with generalized linear mixed models (GLMM). We identified 326 donors with 726 pregnancies, 106 after donation. In unadjusted analysis (Fisher) no differences were observed in the occurrence of preeclampsia (p = 0.22). In the adjusted analysis (GLMM) it was more common in pregnancies after donation, 6/106 (5.7%), than in pregnancies before donation 16/620 (2.6%) (p = 0.026). The occurrence of stillbirths after donation was 3/106 (2.8%), before donation 7/620 (1.1%), in controls (1.1%) (p = 0.17). No differences were observed in the occurrence of adverse pregnancy outcome in kidney donors and in the general population in unadjusted analysis. Our finding of more frequent preeclampsia in pregnancies after kidney donation in the secondary analysis must be interpreted with caution, as the number of events was low.

Primum non Nocere: is chronic kidney disease staging appropriate in living kidney transplant donors?

The aphorism of Primum non Nocere ('first do no harm') was introduced to guide physicians in making difficult and potentially hazardous decisions. The application of estimating equations for glomerular filtration rate (GFR) and classification schema for chronic kidney disease (CKD) has inadvertently led to 'labeling' of many living donors as having CKD postdonation. This review examines this issue and its possible consequences. Although complete long-term studies are lacking, it appears that the 'labeling' of such donors as having CKD postdonation is common but not associated with a major effect on morbidity or mortality.

Pregnancy outcomes after kidney donation

The outcome of pregnancy in kidney donors has generally been viewed to be favorable. We determined fetal and maternal outcomes in a large cohort of kidney donors. A total of 2102 women have donated a kidney at our institution; 1589 donors responded to our pregnancy surveys; 1085 reported 3213 pregnancies and 504 reported none. Fetal and maternal outcomes in postdonation pregnancies were comparable to published rates in the general population. Postdonation (vs. predonation) pregnancies were associated with a lower likelihood of full-term deliveries (73.7% vs. 84.6%, p = 0.0004) and a higher likelihood of fetal loss (19.2% vs. 11.3%, p < 0.0001). Postdonation pregnancies were also associated with a higher risk of gestational diabetes (2.7% vs. 0.7%, p = 0.0001), gestational hypertension (5.7% vs. 0.6%, p < 0.0001), proteinuria (4.3% vs. 1.1%, p < 0.0001) and preeclampsia (5.5% vs. 0.8%, p < 0.0001). Women who had both pre- and post-donation pregnancies were also more likely to have these adverse maternal outcomes in their postdonation pregnancies. In this large survey of previous living donors in a single center, fetal and maternal outcomes and pregnancy outcomes after kidney donation were similar to those reported in the general population, but inferior to predonation pregnancy outcomes.

Reassuring results with regard to the effect of donor nephrectomy on cardiovascular outcomes

This article discusses the conclusions of a retrospective cohort study reported by Garg et al. on behalf of the Donor Nephrectomy Outcomes Research (DONOR) Network. This study compared the incidence of cardiovascular events in a cohort of kidney donors with that in a matched control population, to establish whether living kidney donation is associated with increased cardiovascular risk. Garg et al. found that living kidney donors had a very low risk of death or cardiovascular events that was not significantly different to that of the control population (2.0 vs 2.7 events per 1,000 person-years; hazard ratio 0.7, 95% CI 0.4-1.2). During follow-up, hypertension was diagnosed more frequently among donors than controls, but this finding might reflect the close monitoring of donors. Although the study provides reassuring information for counseling potential kidney donors, the sample of patients was not sufficiently large to resolve uncertainties over the influence of reduced kidney function on the risk of cardiovascular disease.

Risk factors for end-stage renal disease: 25-year follow-up

BACKGROUND

Few cohort studies have focused on risk factors for end-stage renal disease (ESRD). This investigation evaluated the prognostic value of several potential novel risk factors for ESRD after considering established risk factors.

METHODS

We studied 177 570 individuals from a large integrated health care delivery system in northern California who volunteered for health checkups between June 1, 1964, and August 31, 1973. Initiation of ESRD treatment was ascertained using US Renal Data System registry data through December 31, 2000.

RESULTS

A total of 842 cases of ESRD were observed during 5 275 957 person-years of follow-up. This comprehensive evaluation confirmed the importance of established risk factors, including the following: male sex, older age, proteinuria, diabetes mellitus, lower educational attainment, and African American race, as well as higher blood pressure, body mass index, and serum creatinine level. The 2 most potent risk factors were proteinuria and excess weight. For proteinuria, the adjusted hazard ratios (HRs) were 7.90 (95% confidence interval [CI], 5.35-11.67) for 3 to 4+ on urine dipstick, 3.59 (2.82-4.57) for 1 to 2+ on urine dipstick, and 2.37 (1.79-3.14) for trace vs negative on urine dipstick. For excess weight, the HRs were 4.39 (95% CI, 3.38-5.70) for class 2 to class 3 obesity, 3.11 (2.51-3.84) for class 1 obesity, and 1.65 (1.39-1.97) for overweight vs normal weight. Furthermore, several independent novel risk factors for ESRD were identified, including lower hemoglobin level (1.33 [1.08-1.63] for lowest vs highest quartile), higher serum uric acid level (2.14 [1.65-2.77] for highest vs lowest quartile), self-reported history of nocturia (1.36 [1.17-1.58]), and family history of kidney disease (HR, 1.40 [95% CI, 1.02-1.90]).

CONCLUSIONS

We confirmed the importance of established ESRD risk factors in this large cohort with broad sex and racial/ethnic representation. Lower hemoglobin level, higher serum uric acid level, self-reported history of nocturia, and family history of kidney disease are independent risk factors for ESRD.