Impact of metabolic syndrome on postdonation renal function in living kidney donors

Impact of Age 70 years or Older on Donors for Living-Donor Kidney Transplantation

Introduction

Kidney transplantation (KT) involving elderly living kidney donors (LKDs) is becoming more frequent because of a profound organ shortage. The efficacy of KT involving grafts obtained from LKDs aged 70 years or older has been reported. However, the safety of donor nephrectomy in LKDs aged 70 years or older, including that associated with changes in the estimated glomerular filtration rate (eGFR), has not been investigated. This study investigated the outcomes of LKDs aged 70 years or older after donor nephrectomy.

Methods

This single-center, retrospective cohort study included 1226 LKDs who underwent donor nephrectomy between January 2008 and December 2020. LKDs were stratified into the following age groups: 30 to 49 years (244 LKDs), 50 to 69 years (803 LKDs), and 70 to 89 years (179 LKDs). Surgical outcomes, postoperative eGFR changes, end-stage renal disease (ESRD) rates, and mortality rates were compared among these groups.

Results

No significant difference in surgical outcomes was identified among the groups. LKDs aged 70 to 89 years experienced the lowest eGFR changes at all time points and the lowest eGFR improvement; however, ESRD was not identified in any group during the observation period. Mortality was the highest among LKDs aged 70 to 89 years compared to the other age groups.

Conclusion

Surgical outcomes, eGFR changes, and ESRD incidences can support the safety of donor nephrectomy in LKDs aged 70 years or older. Considering the advanced age, the high mortality rates in LKDs aged 70 years or older could be considered acceptable.

Effects of body fat components on early renal functions of individuals following kidney donation

Objective:

Obesity stands as a risk factor for the chronic kidney disease. The objective of this study was to investigate the relationship between early renal function following kidney donation and the measurements of body fat components.

Methods:

In total, 86 donors followed up for at least 6 months postoperatively were included. Height and weight measurements and results of laboratory analysis of all donors were recorded retrospectively. Visceral adipose tissue (VAT), subcutaneous adipose tissue (SAT), hepatic fat (HF), pancreatic fat (PF) and splenic fat (SF) measurements were performed, and pancreatic splenic fat fraction difference (P−S) and pancreatic splenic fat fraction ratio (P/S) were calculated by a radiologist using the records of preoperative computed tomography scans of donors.

Results:

The estimated glomerular filtration rate (eGFR), serum creatinine and spot urinary microalbumin/creatinine ratio values of the donors at the sixth month postoperatively were statistically different from those of the preoperative values ( p < 0.001). In addition, the individuals were divided into two categories based on the postoperative eGFR: ⩾ 60 mL/min/1.73 m2 and < 60 mL/min/1.73 m2. Age, low-density lipoprotein (LDL) level and VAT/SAT ratio were lower in group eGFR: ⩾ 60 ( p < 0.001, p = 0.03, p = 0.007, respectively). Age and VAT/SAT ratio were the parameters found to be affecting the eGFR significantly, and VAT/SAT ratio (0.729, 95% CI: 0.602–0.856, p = 0.007) had higher predictive value in receiver operating characteristic curve (ROC).

Conclusion:

Preoperative measurements of body fat components may provide significant information to predict postoperative renal functions of kidney donor candidates.

Level of evidence:

Not applicable.

Donor‐reported barriers to living kidney donor follow‐up

BACKGROUND

Despite regulations mandating follow-up laboratory testing for living kidney donors, less than half of transplant centers are in compliance. We sought to understand barriers to follow-up testing from the donors' perspective.

METHODS

We surveyed our center's living kidney donors. Binary logistic regression was used to assess factors associated with follow-up testing completion.

RESULTS

Of 185 living kidney donors, 110 (59.4%) participated. Among them, 82 (74.5%) completed 6-month laboratory testing, 76 (69.1%) completed 12-month testing, 68 (61.8%) completed both, and 21 (19.0%) completed neither. Six-month testing completion was strongly associated with 12-month testing completion (OR 9.74, 95%CI: 2.23-42.50; p = .002). Those who disagreed with the statements, "Getting labs checked wasn't a priority for me," (OR for completing 6-month testing: 15.05, 95%CI: 3.70-61.18; p < .001; OR for completing 12-month testing: 5.85, 95%CI: 1.94-17.63; p = .002); and, "I forgot to get labs drawn [until I was reminded]" (OR for completing 6-month testing: 6.93, 95%CI: 1.59-30.08; p = .01; OR for completing 12-month testing: 6.55, 95%CI: 1.98-21.63; p = .002) were more likely to complete testing.

CONCLUSIONS

To our knowledge, this is the only study providing perspective on donor insights regarding the need for follow-up testing post donation. Interventions to influence living donor attitudes toward follow-up testing may improve follow-up.

Hypertension and obesity in living kidney donors

Over the past few decades, the shortage in the kidney donor pool as compared to the increasing number of candidates on the kidney transplant waitlist led to loosening of kidney donors’ acceptance criteria. Hypertension and obesity represent risk factors for chronic kidney disease, both in native kidneys and those in kidney transplant recipients. While great progress has been made in kidney transplantation from living donors to benefit the recipient survival and quality of life, progress has been slow to fully risk-characterize the donors. This review critically reassesses the current state of understanding regarding the risk of end-stage kidney disease in those donors with obesity, hypertension or both. Accurate risk assessment tools need to be developed urgently to fully understand the risk glomerular filtration rate compensation failure in the remaining kidney of the donors.

The need for a living donor wellness program

PURPOSE OF REVIEW

Living donation has a tremendous impact in bridging the gap between the shortage of organs and the growing list of transplant candidates but remains underutilized as a percentage of total transplants performed. This review focuses on obesity and social determinants of health as potential barriers to the expansion of living kidney donation.

RECENT FINDINGS

The growing rate of obesity and associated metabolic syndrome make many potential donors unacceptable as donor candidates because of the future risk for developing chronic health conditions, such as hypertension and diabetes. There is also increasing evidence demonstrating socioeconomic differences and racial disparities potentially limit access to living donation in certain populations. These potentially modifiable factors are not exclusive of each other and together serve as significant contributing factors to lower rates of living donation.

SUMMARY

Living donors make sacrifices to provide the gift of life to transplant recipients, despite the potential risks to their own health. Studies describing risk factors to living donation call attention to the overall need for more action to prioritize and promote the health and well being of living donors.

Preoperative Comorbidities and Outcomes of Medically Complex Living Kidney Donors

Introduction

Recent reports have described an increased risk of renal disease in living kidney donors compared with the general population. However, these reports do not detail the outcomes of medically complex living donors (MCLDs) with preoperative comorbidities (PCs), such as hypertension, dyslipidemia, glucose intolerance, and obesity. Analysis of living donors with end-stage renal disease (ESRD) has shown that these PCs may contribute significantly to the development of ESRD. We aimed to evaluate the effect of PCs on postoperative renal function and mortality in MCLDs.

Methods

Between January 2008 and December 2016, 807 living-donor kidney transplants were performed in our unit. Of these, 802 donors completed postoperative follow-up of >5 months. Donors were stratified into 4 groups based on the number of PCs present: healthy living donors (HLDs) with no PCs (n = 214) or MCLDs with 1 PC (n = 302), 2 PCs (n = 196), or 3 PCs (n = 90) (denoted MCLD [PC 1], MCLD [PC 2], or MCLD [PC 3], respectively). We compared pathology observation data from baseline biopsy, postoperative estimated glomerular filtration rate (eGFR), postoperative urinary protein concentration, and mortality between HLD and MCLD groups.

Results

Interstitial fibrosis, tubular atrophy, glomerulosclerosis, and arteriolosclerosis were more frequent in MCLDs (PC 3) than in HLDs. No significant differences were identified between HLDs and MCLDs in terms of postoperative eGFR and short-term mortality. Overt proteinuria and ESRD were not observed.

Conclusions

Appropriate postdonation management of MCLDs with PCs may result in similar outcomes as for HLDs.

Donation approval among obese living kidney donor candidates: The impact of metabolic syndrome

BACKGROUND

The scarcity of organs available for transplantation has increased attempts to augment transplantation by utilizing obese living kidney donors. The literature has suggested that these donors have increased risks postdonation. Not surprising, the threshold for living kidney donor approval among obese persons is typically higher and the process more costly. Therefore, a screening tool to predict the likelihood of approval among obese living kidney donor candidates was created.

METHODS

A single-center retrospective study was performed among obese (body mass index ≥ 30 kg/m2) living kidney donor candidates evaluated in clinic (January 1, 2012, to December 31, 2017). Approved candidates were compared with those not approved using multivariable logistic regression, and a prediction tool was generated.

RESULTS

Among 389 obese living kidney donor candidates, there were no significant differences in sex or race and ethnicity by approval status. However, nonapproved candidates had a higher prevalence of metabolic syndrome. In the prediction model, glucose impairment and hypertension were most predictive of nonapproval.

CONCLUSION

Among obese living kidney donor candidates, several metabolic syndrome components were associated with decreased odds of approval. This tool may serve as a useful initial screening for obese living kidney donor candidates, permitting more cost-effective evaluation processes. The tool could also be used to promote expeditious interventions in the preclinical setting, including weight management programs, to improve the likelihood of donation and postdonation outcomes.

Preserved Kidney Volume, Body Mass Index, and Age Are Significant Preoperative Factors for Predicting Estimated Glomerular Filtration Rate in Living Kidney Donors at 1 Year After Donation

BACKGROUND

Securing postdonation renal function in the lifetime of donors is a consequential subject for physicians, and precise prediction of postdonation renal function would be considerably beneficial when judging the feasibility of kidney donation. The aim of this study was to investigate the optimum model for predicting eGFR at 1 year after kidney donation.

METHODS

We enrolled 101 living-related kidney donors for the development cohort and 44 for the external validation cohort. All patients in each cohort underwent thin-sliced (1 mm) enhanced computed tomography (CT) scans. We excluded individuals with diabetes, glucose intolerance, or albuminuria from this study. We evaluated preoperative factors including age, sex, hypertension, body mass index (BMI), serum uric acid, baseline eGFR, and body surface area (BSA)-adjusted preserved kidney volume (PKV) by using 3-dimensional reconstruction of thin-sliced enhanced CT images. To detect independent predictors, we performed multivariable regression analysis.

RESULTS

The multivariable regression analysis revealed that age, BMI, predonation eGFR, and BSA-adjusted PKV were independent predictors of eGFR at 1 year after kidney donation (correlation coefficient: -0.15, -0.476, 0.521, 0.127, respectively). A strong correlation between predicted eGFR and observed eGFR was obtained in the development cohort (r = 0.839, P < .0001). The significance of this predictive model was also confirmed with the external validation cohort (r = 0.797, P < .0001).

CONCLUSIONS

Age, BMI, predonation eGFR, and BSA-adjusted PKV may be useful for precisely predicting eGFR at 1 year after living kidney donation and be helpful to determine the feasibility of kidney donation from marginal donors.

Pre-donation BMI and preserved kidney volume can predict the cohort with unfavorable renal functional compensation at 1-year after kidney donation

BACKGROUND

The magnitude of renal function recovery after kidney donation differs in donors with a heterogeneous background. Preoperative assessment of candidates with potentially unfavorable renal functional compensation is critical when baseline kidney function is marginal. We explored the significance of preserved kidney volume (PKV) and known preoperative risk factors for the prediction of unfavorable renal function compensation.

METHODS

We enrolled 101 living donors for whom a 1-mm sliced enhanced computed tomography scan was performed preoperatively and clinical data could be collected up to 1 year after donation. The donors whose estimated glomerular filtration rate (eGFR) at 1 year after donation was 70% or higher of baseline eGFR were assigned to the "favorable renal compensation" group and the others to the "unfavorable renal compensation" group.

RESULTS

Age, sex, and preoperative serum uric acid level were not significant predictors for "unfavorable renal compensation." Multivariable logistic regression analysis revealed that body mass index (BMI) and body surface area (BSA)-adjusted PKV were independent preoperative risk factors for "unfavorable renal compensation" (adjusted odds ratio, 1.342 and 0.929, respectively). Hypertension and preoperative eGFR were not independent predictors when adjusted with BMI and BSA-adjusted PKV. Receiver operative characteristic analysis revealed that the predictive equation with the two independent predictors yielded a good accuracy to detect donor candidates with unfavorable renal functional compensation (area under the curve = 0.803), and the optimal cut-off values were identified as 23.4 kg/m² for BMI and 107.3 cm³/m² for BSA-adjusted PKV.

CONCLUSIONS

BMI and BSA-adjusted PKV may be useful to select candidates with potentially unfavorable renal function compensation before kidney donation.

Impact of the Ratio of Visceral to Subcutaneous Adipose Tissue in Donor Nephrectomy Patients

OBJECTIVE

It was reported that a metabolic syndrome affected the remaining renal function after living donor nephrectomy. However, the measurement of waist circumference is unclear because it cannot distinguish between visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT). We investigate the clinical correlation between body adipose tissue and renal function recovery after living donor nephrectomy.

METHODS

From July 2013 to February 2015, 75 living kidney donors were enrolled. The VAT and SAT were measured by preoperative computed tomography (CT) scan. Body mass index (BMI), VAT, SAT, and VAT-to-SAT ratio were analyzed according to a postoperative renal function recovery. Receiver operating characteristic (ROC) was performed to predict estimated glomerular filtration rate (eGFR) less than 60 mL/min/1.73 m² at postoperative 6 months for BMI, VAT, SAT, and VAT-to-SAT ratio.

RESULTS

The lowest value of eGFR (57.52 ± 11.20 mL/min/1.73 m²) was measured at postoperative day 7. There was no statistically significant difference in eGFR between 1 month and 3 months. BMI, VAT, SAT, and VAT-to-SAT ratio showed a statistically significant correlation with each other (Pearson correlation, P < .05). Also, the recovery time of eGFR was correlated with VAT-to-SAT ratio; it was significant at postoperative 1, 3, and 6 months. VAT-to-SAT ratio (0.654, 95% confidence interval 0.525-0.783, P = .024) had higher predictive value in ROC.

CONCLUSION

We developed a new variable to predict the value of lower eGFR (less than 60 mL/min/1.73 m²) at a postoperative 6 months in living kidney donor. According to a CT scan, VAT-to-SAT ratio can predict renal function recovery.

Predictive model of 1-year postoperative renal function after living donor nephrectomy

OBJECTIVE

Kidney transplantation from a living donor nephrectomy (LDN) is the best treatment for end-stage renal disease, but decrease in donor renal function is often revealed. The aim of this study was to evaluate the association between preoperative factors and postoperative estimated glomerular filtration rate (eGFR) and test a predictive model to estimate postoperative eGFR, 1 year after LDN.

PATIENTS AND METHODS

We reviewed 226 records of consecutive patients who underwent laparoscopic live donor nephrectomy between 2006 and 2014 in a single tertiary center. Of these, complete data on 202 patients were analyzed. A training (2/3 of the whole population) and a validation set (1/3) were randomized. A multivariate regression model was used to identify predictors and a formula to estimate of 1-year postoperative eGFR in the training set, using the CKD-EPI formula. Then, the formula was subjected to internal validation using the validation set using receiver operating characteristic (ROC) curves.

RESULTS

Two hundred and two LLDN were evaluated with a mean preoperative eGFR of 94.1 ± 15.5 ml/min/1.73 m² and postoperative eGFR of 64.6 ± 14.5 ml/min/1.73 m² (p < 0.0001). In multivariable analysis, age and preoperative eGFR were independent predictors of postoperative eGFR in the training set. A formula to estimate postoperative eGFR was generated with Pearson r = 0.70 in the training cohort and 0.65 in the validation cohort (both p < 0.0001). Area under the ROC curve of the formula was 0.89 in the training cohort and 0.83 in the validation cohort (both p < 0.0001).

CONCLUSIONS

Preoperative eGFR and age are predictors of postoperative eGFR after LDN. The internally validated predictive model of postoperative eGFR developed could be an accurate tool to improve the selection of LDN candidates.

Compensatory Structural and Functional Adaptation After Nephrectomy in Obese Patients According to Waist Circumference

OBJECTIVE

To investigate whether the postnephrectomy renal adaptation mechanism, focused on functional hyperfiltration as well as structural hypertrophy, was affected by abdominal obesity.

MATERIALS AND METHODS

We retrospectively evaluated 358 patients who underwent simple or radical nephrectomy and nephroureterectomy between 2009 and 2013. Patients were classified according to waist circumference (WC), with values >102 cm in men and >88 cm in women considered high (obesity). Functional renal volume (FRV) was measured using computed tomography performed preoperatively and 6 months postoperatively to evaluate the degree of remnant kidney hypertrophy. The degree of hyperfiltration was calculated from the difference between the preoperative and postoperative glomerular filtration rate (GFR)/FRV.

RESULTS

The mean preoperative GFR, FRV, and GFR/FRV were 72.1 mL/min/1.73 m², 282.8 cm³, and 0.25 mL/min/1.73 m²/cm³, respectively. The percent GFR reduction was significantly greater in the high WC group (high, 25.9% vs normal, 16.0%, P = .036), although the degree of hypertrophic volume in the remnant kidney showed no difference. The change in GFR/FRV was statistically lower in the high WC group (high, 25.7% vs normal, 40.2%, P = .009). The factors associated with postoperative increased GFR/FRV were low preoperative GFR, proteinuria, high predictive preserved functional parenchymal volume ratio, absence of hypertension, increased levels of high-density lipoprotein cholesterol, and normal WC (all P < .05).

CONCLUSION

Patients with high WC might have a large reduction in postoperative renal function, owing to a lower degree of functional hyperfiltration.

Abdominal Aortic Calcification in Living Kidney Donors

OBJECTIVE

This study assesses the association between abdominal aortic calcification (AAC) and renal function of living kidney donors and evaluate AAC as a surrogate marker for nephrosclerosis.

METHODS

Between January 2010 and March 2013, 287 donors who underwent living donor nephrectomy were enrolled. We analyzed computed tomography angiographies and quantified AAC scores by calculating the Agatston score for the abdominal aorta. The donors were stratified into the non-AAC group (AAC score = 0; n = 238) and the AAC group (AAC score >0; n = 49). The relationship between AAC and perioperative estimated glomerular filtration rate was analyzed. For the 180 donors consenting to implantation biopsy, the nephrosclerosis score was defined as the sum of abnormalities, including glomerulosclerosis, tubular atrophy, interstitial fibrosis, and arteriosclerosis.

RESULTS

The mean AAC score was 185.5 ± 263.3 in the AAC group. The AAC group was older than the non-AAC group (51.1 ± 6.1 vs 37.9 ± 11 years; P < .001). Perioperative renal function was not different between the 2 groups. However, among the AAC group, donors with an AAC score of >100 were associated with delayed renal function recovery (P = .035). Donors with AAC were more likely to have glomerulosclerosis (50.0% vs 29.1%; P = .022), tubular atrophy (62.5% vs 33.1%; P = .002), and a higher nephrosclerosis score (P = .002).

CONCLUSIONS

Living donors with an AAC score of >100 require close observation because they have a higher probability of delayed renal function recovery after donation. AAC is associated with nephrosclerosis in healthy adults.

Risk Factors Associated with Decreased Renal Function after Hand-Assisted Laparoscopic Donor Nephrectomy: A Multivariate Analysis of a Single Surgeon Experience

Background: Hand-assisted laparoscopic donor nephrectomy is a minimally invasive procedure for living kidney donation. The surgeon operative volume is associated with postoperative morbidity and mortality. We evaluated the risk factors associated with decreased renal function after hand-assisted laparoscopic donor nephrectomy performed by a single experienced surgeon. Methods: We included living renal donors who underwent hand-assisted laparoscopic donor nephrectomy by a single experienced surgeon between 2006 and 2013. Decreased renal function was defined as an estimated glomerular filtration rate (eGFR) of < 60 mL/min/1.73 m² on postoperative day 4. The donors were categorized into groups with postoperative eGFR < 60 mL/min/1.73 m² or ≥ 60 mL/min/1.73 m². Univariate and multivariate logistic regression analyses were performed to evaluate the risk factors associated with decreased renal function after hand-assisted laparoscopic donor nephrectomy. The hospital stay duration, intensive care unit admission rate, and eGFR at postoperative year 1 were evaluated. Results: Of 643 patients, 166 (25.8%) exhibited a postoperative eGFR of < 60 mL/min/1.73 m². Multivariate logistic regression analysis demonstrated that the risk factors for decreased renal function were age [odds ratio (95% confidence interval), 1.062 (1.035-1.089), P < 0.001], male sex [odds ratio (95% confidence interval), 3.436 (2.123-5.561), P < 0.001], body mass index (BMI) [odds ratio (95% confidence interval), 1.093 (1.016-1.177), P = 0.018], and preoperative eGFR [odds ratio (95% confidence interval), 0.902 (0.881-0.924), P < 0.001]. There were no significant differences in postoperative hospital stay duration and intensive care unit admission rate between the two groups. In addition, 383 of 643 donors were analyzed at postoperative year 1. Sixty donors consisting of 14 (5.0%) from the group of 279 donors in eGFR ≥ 60 mL/min/1.73 m², and 46 (44.2%) from the group of 104 donors in eGFR < 60 mL/min/1.73 m² had eGFR < 60 mL/min/1.73 m² at postoperative year 1 (P < 0.001). Conclusions: Increased age, male sex, higher BMI, and decreased preoperative eGFR were risk factors for decreased renal function after hand-assisted laparoscopic donor nephrectomy by a single experienced surgeon. These results provide important evidence for the safe perioperative management of living renal donors.

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.