The survival benefit of kidney transplantation in obese patients

Obesity as an isolated contraindication to kidney transplantation in the end-stage renal disease population: A cohort study

OBJECTIVE

The aim of this study was to characterize end-stage renal disease (ESRD) patients with obesity as their only contraindication to listing and to quantify wait-list and transplant access.

METHODS

Using the US Renal Data System, a retrospective cohort study of incident dialysis cases (2012 to 2014) was performed. The primary outcomes were time to wait-listing and time to transplantation.

RESULTS

Of 157,572 dialysis patients not already listed, 39,844 had BMI as their only demonstrable transplant contraindication. They tended to be younger, female, and Black. Compared with patients with BMI < 35, those with BMI 35 to 39.9, 40 to 44.9, and ≥45 were, respectively, 15% (adjusted hazard ratio [aHR] 0.85; 95% CI: 0.83-0.88; p < 0.001), 45% (aHR 0.55; 95% CI: 0.52-0.57; p < 0.001), and 71% (aHR 0.29; 95% CI: 0.27-0.31; p < 0.001) less likely to be wait-listed. Wait-listed patients with BMI 35 to 39.9 were 24% less likely to achieve transplant (aHR 0.76; 95% CI: 0.72-0.80; p < 0.0001), BMI 40 to 44.9 were 21% less likely (aHR 0.79; 95% CI: 0.72-0.86; p < 0.0001), and BMI ≥ 45 were 15% less likely (aHR 0.85; 95% CI: 0.75-0.95; p = 0.004) compared with patients with BMI < 35.

CONCLUSIONS

Obesity was the sole contraindication to wait-listing for 40,000 dialysis patients. They were less likely to be wait-listed. For those who were, they had a lower likelihood of transplant. Aggressive weight-loss interventions may help this population achieve wait-listing and transplant.

Long-term kidney transplant graft survival-Making progress when most needed

Current short-term kidney post-transplant survival rates are excellent, but longer-term outcomes have historically been unchanged. This study used data from the national Scientific Registry of Transplant Recipients (SRTR) and evaluated 1-year and 5-year graft survival and half-lives for kidney transplant recipients in the US. All adult (≥18 years) solitary kidney transplants (n = 331,216) from 1995 to 2017 were included in the analysis. Mean age was 49.4 years (SD +/-13.7), 60% male, and 25% Black. The overall (deceased and living donor) adjusted hazard of graft failure steadily decreased from 0.89 (95%CI: 0.88, 0.91) in era 2000-2004 to 0.46 (95%CI: 0.45, 0.47) for era 2014-2017 (1995-1999 as reference). Improvements in adjusted hazards of graft failure were more favorable for Blacks, diabetics and older recipients. Median survival for deceased donor transplants increased from 8.2 years in era 1995-1999 to an estimated 11.7 years in the most recent era. Living kidney donor transplant median survival increased from 12.1 years in 1995-1999 to an estimated 19.2 years for transplants in 2014-2017. In conclusion, these data show continuous improvement in long-term outcomes with more notable improvement among higher-risk subgroups, suggesting a narrowing in the gap for those disadvantaged after transplantation.

Kidney and pancreas transplant candidacy

PURPOSE OF REVIEW

Kidney and/or pancreas transplantation candidacy criteria have evolved significantly over time reflecting improved pre and post-transplant management. With improvement in medical care, potential candidates for transplant not only are older but also have complex medical issues. This review focuses on the latest trends regarding candidacy for kidney and/or pancreas transplantation along with advances in pretransplant cardiac testing.

RECENT FINDINGS

More candidates are now eligible for kidney and/or pancreas transplantation owing to less stringent candidacy criteria especially in regards to age, obesity, frailty and history of prior malignancy. Pretransplant cardiovascular assessment has also come a long way with a focus on less invasive strategies to assess for coronary artery disease.

SUMMARY

Criteria for kidney and/or pancreas transplantation are expanding. Patients who in the past might have been declined because of numerous factors are now finding that transplant centers are more open minded to their candidacy, which could lead to better access to organ transplant wait list.

Is Bigger Better? Living Donor Kidney Volume as Measured by the Donor CT Angiogram in Predicting Donor and Recipient eGFR after Living Donor Kidney Transplantation

BACKGROUND

The role of kidney volume measurement in predicting the donor and recipient kidney function is not clear.

METHODS

We measured kidney volume bilaterally in living kidney donors using CT angiography and assessed the association with the donor remaining kidney and recipient kidney (donated kidney) function at 1 year after kidney transplantation. Donor volume was categorized into tertiles based on lowest, middle, and highest volume.

RESULTS

There were 166 living donor and recipient pairs. The mean donor age was 44.8 years (SD ± 10.8), and donor mean BMI was 25.5 (SD ± 2.9). The recipients of living donor kidneys were 64% male and had a mean age of 43.5 years (SD ± 13.3). Six percent of patients experienced an episode of cellular rejection and were maintained on dialysis for a mean of 18 months (13-32) prior to transplant. Kidney volume was divided into tertiles based on lowest, middle, and highest volume. Kidney volume median (range) in tertiles 1, 2, and 3 was 124 (89-135 ml), 155 (136-164 ml), and 184 (165-240 ml) with donor eGFR ml/min (adjusted for body surface area expressed as ml/min/1.73 m2) at the time of donation in each tertile, 109 (93-129), 110 (92-132), and 101 ml/min (84-117). The median (IQR) eGFR in tertiles 1 to 3 in kidney recipients at 1 year after donation was 54 (44-67), 62 (50-75), and 63 ml/min (58-79), respectively. The median (IQR) eGFR in tertiles 1 to 3 in the remaining kidney of donors at 1 year after donation was 59 (53-66), 65 (57-72), and 65 ml/min (56-73), respectively.

CONCLUSION

Bigger kidney volume was associated with better eGFR at 1 year after transplant in the recipient and marginally in the donor remaining kidney.

Patients with High Priority for Kidney Transplant Who Are Not Given Expedited Placement on the Transplant Waiting List Represent Lost Opportunities

BACKGROUND

Kidney transplantation is associated with the best outcomes for most patients with ESKD. The national Kidney Allocation System prioritizes patients with Estimated Post-Transplant Survival (EPTS) scores in the top 20% for expedited access to optimal deceased donor kidneys.

METHODS

We studied adults aged ≥18 years in the United States Renal Data System with top 20% EPTS scores who had been preemptively waitlisted or initiated dialysis in 2015-2017. We evaluated time to waitlist placement, transplantation, and mortality with unadjusted and multivariable survival models.

RESULTS

Of 42,445 patients with top 20% EPTS scores (mean age, 38.0 years; 57% male; 59% White patients, and 31% Black patients), 7922 were preemptively waitlisted. Among 34,523 patients initiating dialysis, the 3-year cumulative waitlist placement incidence was 37%. Numerous factors independently associated with waitlisting included race, income, and having noncommercial insurance. For example, waitlisting was less likely for Black versus White patients, and for patients in the lowest-income neighborhoods versus those in the highest-income neighborhoods. Among patients initiating dialysis, 61% lost their top 20% EPTS status within 30 months versus 18% of patients who were preemptively listed. The 3-year incidence of deceased and living donor transplantation was 5% and 6%, respectively, for patients who initiated dialysis and 26% and 44%, respectively, for patients who were preemptively listed.

CONCLUSIONS

Many patients with ESKDqualifying with top 20% EPTS status are not placed on the transplant waiting list in a timely manner, with significant variation on the basis of demographic and social factors. Patients who are preemptively listed are more likely to receive benefits of top 20% EPTS status. Efforts to expedite care for qualifying candidates are needed, and automated transplant referral for patients with the best prognoses should be considered.

PODCAST

This article contains a podcast athttps://www.asn-online.org/media/podcast/JASN/2021_07_30_JASN2020081146.mp3.

Obesity in Renal Transplantation

BACKGROUND

Data from the WHO show an increasing rate of overweight and obesity in general population in the last decades. This increase in obesity also affects population with end-stage renal disease (ESRD) and kidney transplant (KT) candidates.

SUMMARY

In this review, we focused on how obesity impacts on KT stages: access to KT and outcomes of KT candidates; how to reduce weight and its consequences; short and long-term outcomes in obese recipients and the impact of weight variations; and the implications of obesity in living donor KT. We searched MEDLINE, EMBASE, and Cochrane Central Register of Controlled Trials until November 30, 2020. We selected systematic reviews and meta-analyses and randomized clinical trials. When no such reports were found for a topic, observational studies were included in the assessment. Key Messages: Although obesity is a risk factor to present worst outcomes after KT, several studies have demonstrated a survival benefit compared to patients who continue on dialysis. There is a need for a public health campaign to raise awareness in KT candidates and to highlight the importance of self-care, increasing exercise, healthy diet, and weight loss.

Recipient Obesity and Kidney Transplant Outcomes: A Mate-Kidney Analysis

RATIONALE & OBJECTIVE

The impact of extreme recipient obesity on long-term kidney transplant outcomes has been controversial. This study sought to evaluate the association of various levels of recipient obesity on kidney transplantation outcomes by comparing mate-kidney recipient pairs to address possible confounding effects of donor characteristics on posttransplant outcomes.

STUDY DESIGN

Nationwide observational cohort study using mate-kidney models.

SETTING & PARTICIPANTS

In analysis based on the Organ Procurement and Transplant Network/United Network of Organ Sharing database, 44,560 adult recipients of first-time deceased-donor kidney transplants from 2001 through 2016 were paired by donor.

PREDICTORS

Recipient body mass index (BMI) categorized as 18-25 (n = 12,446), >25-30 (n = 15,477), >30-35 (n = 11,144; obese), and >35 (n = 5,493; extreme obesity) kg/m².

OUTCOMES

Outcomes included patient survival, graft survival, death-censored graft survival, delayed graft function (DGF), and hospital length of stay.

ANALYTICAL APPROACH

Conditional logistic regression and stratified proportional hazards models were used to compare outcomes as odds ratios and hazard ratios (HRs), adjusted for recipient and transplant factors, using recipients with a BMI >35 kg/m² as a reference.

RESULTS

At a median follow-up of 3.9 years, adjusted odds ratios for DGF were 0.42 (95% CI, 0.36-0.48), 0.55 (95% CI, 0.48-0.62), and 0.73 (95% CI, 0.64-0.83) for BMI 18-25, >25-30, and >30-35 kg/m², respectively (P < 0.001 for all). Death-censored graft failure was less frequent for BMI ≤25 and >25-30 kg/m² (HRs of 0.66 [95% CI, 0.59-0.74] and 0.79 [95% CI, 0.70-0.88], respectively; P < 0.001 for both), but not for BMI >30-35 kg/m² (HR, 0.91 [95% CI, 0.81-1.02]; P = 0.09). Length of stay and patient survival did not differ by recipient BMI.

LIMITATIONS

Observational study with limited detail regarding potential confounders.

CONCLUSIONS

Despite an increased risk of DGF likely unrelated to donor organ quality, long-term transplant outcomes among recipients with a BMI >35 kg/m² are similar to those among recipients with a BMI >30-35 kg/m², supporting a flexible approach to kidney transplantation candidacy in candidates with extreme obesity.

Failure to Advance Access to Kidney Transplantation over Two Decades in the United States

BACKGROUND

Extensive research and policies have been developed to improve access to kidney transplantation among patients with ESKD. Despite this, wide variation in transplant referral rates exists between dialysis facilities.

METHODS

To evaluate the longitudinal pattern of access to kidney transplantation over the past two decades, we conducted a retrospective cohort study of adult patients with ESKD initiating ESKD or placed on a transplant waiting list from 1997 to 2016 in the United States Renal Data System. We used cumulative incidence models accounting for competing risks and multivariable Cox models to evaluate time to waiting list placement or transplantation (WLT) from ESKD onset.

RESULTS

Among the study population of 1,309,998 adult patients, cumulative 4-year WLT was 29.7%, which was unchanged over five eras. Preemptive WLT (prior to dialysis) increased by era (5.2% in 1997-2000 to 9.8% in 2013-2016), as did 4-year WLT incidence among patients aged 60-70 (13.4% in 1997-2000 to 19.8% in 2013-2016). Four-year WLT incidence diminished among patients aged 18-39 (55.8%-48.8%). Incidence of WLT was substantially lower among patients in lower-income communities, with no improvement over time. Likelihood of WLT after dialysis significantly declined over time (adjusted hazard ratio, 0.80; 95% confidence interval, 0.79 to 0.82) in 2013-2016 relative to 1997-2000.

CONCLUSIONS

Despite wide recognition, policy reforms, and extensive research, rates of WLT following ESKD onset did not seem to improve in more than two decades and were consistently reduced among vulnerable populations. Improving access to transplantation may require more substantial interventions.

Management of Obesity in Adults with CKD

Obesity is a leading public health problem that currently affects over 650 million individuals worldwide. Although interest in the adverse effects of obesity has grown exponentially in recent years, less attention has been given to studying its management in individuals with CKD. This relatively unexplored area should be considered a high priority because of the rapid growth and high prevalence of obesity in the CKD population, its broad impact on health and outcomes, and its modifiable nature. This article begins to lay the groundwork in this field by providing a comprehensive overview that critically evaluates the available evidence related to obesity and kidney disease, identifies important gaps in our knowledge base, and integrates recent insights in the pathophysiology of obesity to help provide a way forward in establishing guidelines as a basis for managing obesity in CKD. Finally, the article includes a kidney-centric algorithm for management of obesity that can be used in clinical practice.

Tacrolimus Exposure in Obese Patients: and A Case-Control Study in Kidney Transplantation

BACKGROUND

Tacrolimus pharmacokinetics in obese (Ob) patients has been poorly studied. In this article, the authors explored the impact of obesity on tacrolimus exposure in kidney transplant recipients (KTRs) and estimated a more suitable initial dosage in this population.

METHODS

A retrospective, observational, monocentric case-control study was performed in obese KTRs (BMI > 30 kg/m2) who received tacrolimus between 2013 and 2017 (initial dose: 0.15 mg/kg/d) (actual weight). Nonobese (Nob) controls (BMI <30 kg/m2) were matched for age and sex. Weekly centralized monitoring of tacrolimus trough levels was performed by liquid chromatography/mass spectrometry until the third month (M3). Target trough levels were set between 8 and 10 ng/mL. All patients received antilymphocyte globulin, corticosteroids, and mycophenolate mofetil.

RESULTS

Of the 541 KTRs, 28 tacrolimus-treated Ob patients were included and compared with 28 NOb-matched controls. With a mean of 22 assays/patient, tacrolimus trough levels were higher in Ob patients (mean 9.9 versus 8.7 ng/mL; P = 0.008); the weight-related dose of Tac was lower at M3 (mean 0.10 versus 0.13 mg/kg/d, P < 0.0001). The tacrolimus concentration to dose (C0/D) was higher in the Ob cohort [mean 116 versus 76 (ng/mL)/(mg/kg/d); P = 0.001]. In Ob patients, a mean decrease of -4.6 mg/d in the 3 months after tacrolimus initiation was required (versus -1.12 in NOb; P = 0.001) to remain within the therapeutic range. Obesity, high mycophenolate mofetil daily dose at M3, and CYP3A5 expression were independently associated with higher tacrolimus exposure. Four dose-adaptation strategies were simulated and compared with the study results.

CONCLUSIONS

An initial dose calculation based on either ideal or lean body weight may allow for faster achievement of tacrolimus trough level targets in Ob KTRs, who are at risk of overexposure when tacrolimus is initiated at 0.15 mg/kg/d. A prospective study is required to validate alternative dose calculation strategies in these patients.

KDOQI US Commentary on the 2020 KDIGO Clinical Practice Guideline on the Evaluation and Management of Candidates for Kidney Transplantation

Evaluation of patients for kidney transplant candidacy is a comprehensive process that involves a detailed assessment of medical and surgical issues, psychosocial factors, and patients' physical and cognitive abilities with an aim of balancing the benefits of transplantation and potential risks of surgery and long-term immunosuppression. There is considerable variability among transplant centers in their approach to evaluation and decision-making regarding transplant candidacy. The 2020 KDIGO (Kidney Disease: Improving Guidelines Outcome) clinical practice guideline on the evaluation and management of candidates for kidney transplantation provides practice recommendations that can serve as a useful reference guide to transplant professionals. The guideline, covering a broad range of topics, was developed by an international group of experts from transplant and nephrology through a review of literature published until May 2019. A work group of US transplant nephrologists convened by NKF-KDOQI (National Kidney Foundation-Kidney Disease Quality Initiative) chose key topics for this commentary with a goal of presenting a broad discussion to the US transplant community. Each section of this article has a summary of the key KDIGO guideline recommendations, followed by a brief commentary on the recommendations, their clinical utility, and potential implementation challenges. The KDOQI work group agrees broadly with the KDIGO recommendations but also recognizes and highlights the decision-making challenges that arise from lack of high-quality evidence and the need to balance equity with utility of organ transplantation.

[Living-donor robotic-assisted kidney transplantation: French academic center experience]

INTRODUCTION

The main objective was to report the intra-, post-operative and functional outcomes of living-donor robotic-assisted kidney transplantation (RAKT), performed by a surgeon skilled in robotic surgery. The secondary objective was to compare the results of RAKT, based on the surgeon's experience.

METHODS

For this retrospective cohort study, we analyzed data from consecutive patients who underwent living-donor RAKT from July 2015 to March 2020 and compared the results of RAKT according to the surgeon's experience (group 1: 1-14th RAKT versus group 2: 15-29th RAKT).

RESULTS

Twenty-nine living-donor RAKT were performed. The median age and BMI of the recipients were: 57.0 (44.0-66.0) years and 32.7 (23.5-39.6)kg/m². The median overall operative time and median console time were: 140.0 (122.5-165.0) and 120.0 (107.5-137.5) minutes. The median rewarming time, arterial, venous and urinary anastomoses durations were: 35.0 (27.5-45.0), 15.0 (11.0-20.0), 12.0 (10.0-16.0), 20.0 (16.0-23.0) minutes. Two (6.9%) minor and 5 (17.2%) major (Clavien-Dindo≥III) postoperative complications occurred. At 2 years of follow-up, patient and transplant survival was 100% (n=29) and 93.1% (n=27). After the 14th RAKT, the rewarming time (P=0.01) and venous anastomosis duration (P=0.004) were statistically shorter.

CONCLUSION

Living-donor robotic-assisted kidney transplantation, performed by a surgeon skilled robotic surgery, ensures good functional results in the medium term.

LEVEL OF EVIDENCE

3.

KDIGO Clinical Practice Guideline on the Evaluation and Management of Candidates for Kidney Transplantation

The 2020 Kidney Disease: Improving Global Outcomes (KDIGO) Clinical Practice Guideline on the Evaluation and Management of Candidates for Kidney Transplantation is intended to assist health care professionals worldwide who evaluate and manage potential candidates for deceased or living donor kidney transplantation. This guideline addresses general candidacy issues such as access to transplantation, patient demographic and health status factors, and immunological and psychosocial assessment. The roles of various risk factors and comorbid conditions governing an individual's suitability for transplantation such as adherence, tobacco use, diabetes, obesity, perioperative issues, causes of kidney failure, infections, malignancy, pulmonary disease, cardiac and peripheral arterial disease, neurologic disease, gastrointestinal and liver disease, hematologic disease, and bone and mineral disorder are also addressed. This guideline provides recommendations for evaluation of individual aspects of a candidate's profile such that each risk factor and comorbidity are considered separately. The goal is to assist the clinical team to assimilate all data relevant to an individual, consider this within their local health context, and make an overall judgment on candidacy for transplantation. The guideline development process followed the Grades of Recommendation Assessment, Development, and Evaluation (GRADE) approach. Guideline recommendations are primarily based on systematic reviews of relevant studies and our assessment of the quality of that evidence, and the strengths of recommendations are provided. Limitations of the evidence are discussed with differences from previous guidelines noted and suggestions for future research are also provided.

Effects of body mass index on kidney transplant outcomes are significantly modified by patient characteristics

Body mass index (BMI) is a known risk factor associated with kidney transplant outcomes and is incorporated for determining transplant candidate eligibility. However, BMI is a coarse health measure and risks associated with BMI may vary by patient characteristics. We evaluated 296 807 adult (age > 17) solitary kidney transplant recipients from the Scientific Registry of Transplant Recipients (2000-2019). We examined effects of BMI using survival models and tested interactions with recipient characteristics. Overall, BMI demonstrated a "J-Shaped" risk profile with elevated risks for overall graft loss with low BMI and obesity. However, multivariable models indicated interactions between BMI with recipient age, diagnosis, gender, and race/ethnicity. Low BMI was relatively higher risk for older recipients (>60 years), people with type I diabetes, and males and demonstrated no additional risk among younger (18-39) and Hispanic recipients. High BMI was associated with elevated risk for Caucasians and attenuated risk among African Americans and people with type II diabetes. Effects of BMI had variable risks for mortality vs graft loss by recipient characteristics in competing risks models. The association of BMI with posttransplant outcomes is highly variable among kidney transplant recipients. Results are important considerations for personalized care and risk stratification. Findings suggest that transplant contraindications should not be based on absolute BMI thresholds but modified based on patient characteristics.

Clinical outcome of kidney transplantation after bariatric surgery: A single-center, retrospective cohort study

Patients with class II and III obesity and end‐stage renal disease are often ineligible for kidney transplantation (KTx) due to increased postoperative complications and technically challenging surgery. Bariatric surgery (BS) can be an effective solution for KTx candidates who are considered inoperable. The aim of this study is to evaluate outcomes of KTx after BS and to compare the outcomes to obese recipients (BMI ≥ 35 kg/m²) without BS. This retrospective, single‐center study included patients who received KTx after BS between January 1994 and December 2018. The primary outcome was postoperative complications. The secondary outcomes were graft and patient survival. In total, 156 patients were included, of whom 23 underwent BS prior to KTx. There were no significant differences in postoperative complications. After a median follow‐up of 5.1 years, death‐censored graft survival, uncensored graft survival, and patient survival were similar to controls (log rank test p = .845, .659, and .704, respectively). Dialysis pre‐transplantation (Hazard Ratio (HR) 2.55; 95%CI 1.03–6.34, p = .043) and diabetes (HR 2.41; 95%CI 1.11–5.22, p = .027) were independent risk factors for all‐cause mortality. A kidney from a deceased donor was an independent risk factor for death‐censored graft loss (HR 1.98; 95%CI 1.04–3.79, p = .038). Patients who received a KTx after BS have similar outcomes as obese transplant recipients.

An overview of frailty in kidney transplantation: measurement, management and future considerations

The construct of frailty was first developed in gerontology to help identify older adults with increased vulnerability when confronted with a health stressor. This article is a review of studies in which frailty has been applied to pre- and post-kidney transplantation (KT) populations. Although KT is the optimal treatment for end-stage kidney disease (ESKD), KT candidates often must overcome numerous health challenges associated with ESKD before receiving KT. After KT, the impacts of surgery and immunosuppression represent additional health stressors that disproportionately impact individuals with frailty. Frailty metrics could improve the ability to identify KT candidates and recipients at risk for adverse health outcomes and those who could potentially benefit from interventions to improve their frail status. The Physical Frailty Phenotype (PFP) is the most commonly used frailty metric in ESKD research, and KT recipients who are frail at KT (~20% of recipients) are twice as likely to die as nonfrail recipients. In addition to the PFP, many other metrics are currently used to assess pre- and post-KT vulnerability in research and clinical practice, underscoring the need for a disease-specific frailty metric that can be used to monitor KT candidates and recipients. Although frailty is an independent risk factor for post-transplant adverse outcomes, it is not factored into the current transplant program risk-adjustment equations. Future studies are needed to explore pre- and post-KT interventions to improve or prevent frailty.

Obesity and gender-biased access to deceased donor kidney transplantation

BACKGROUND

Despite the survival advantage of transplantation over dialysis, obese patients are less likely to be listed on the deceased donor waiting list and subsequently transplanted. This study aimed to determine the association between obesity and access to deceased donor transplantation and whether any association observed was applicable to men and women equally.

METHODS

Cox proportional hazards models were conducted to determine the association between obesity and waitlisting for transplantation and then subsequent receipt of a kidney transplant using data from the Australian and New Zealand Dialysis and Transplant Registry (2007-14).

RESULTS

Of 11633 patients included, 4408 (37.9%) were obese. Over a follow-up period of 26306 patient-years during waitlisting and 5607 patient-years from waitlisting to transplantation, 3515 candidates were listed (28.4% obese) and 1662 were transplanted (29.3% obese). Obesity was associated with a reduced likelihood of waitlisting {adjusted hazard ratio [aHR] 0.66 [95% confidence interval (CI) 0.58-0.76]} but not kidney transplantation once waitlisted [aHR 1.10 (95% CI 0.97-1.24)]. The impact of obesity and waitlisting was modified by gender (P-value for interaction = 0.01). Women who were obese were 34% less likely to be listed than normal-weight women [aHR 0.66 (95% CI 0.58-0.76)], compared with obese men who were 14% less likely [aHR 0.86 (95% CI 0.77-0.97)].

CONCLUSIONS

Overall, obesity reduces the likelihood of being listed for deceased donor transplantation, especially among women, but not transplantation once listed. Transplant physicians who regulate access to the deceased donor waiting list should be aware of this apparent inequity and seek to understand and ameliorate contributing factors.

ABO-Incompatible Robotic-Assisted Kidney Transplantation in the Obese Recipient

Objective: The objective of this preliminary study was to report and compare the peri-operative and functional results of ABO-incompatible (ABOi) living-donor robotic-assisted kidney transplantation (RAKT), ABO-compatible (ABOc) living-donor RAKT, and ABOi living-donor open kidney transplantation (OKT).

Materials and Methods: For the present retrospective study, we analyzed data of consecutive patients who underwent ABOi or ABOc-RAKT and ABOi-OKT, from January 2015 to December 2019, in one French academic center. Patients' baseline characteristics, operative, and functional outcomes were compared between ABOi-RAKT, ABOc-RAKT, and ABOi-OKT.

Results: 29 RAKT, including 7 ABOi-RAKT, and 56 ABOi-OKT were performed in our center. Median follow-up was 2.0 years. Median recipient age, pre-emptive kidney transplantation rate, sex ratio and desensitization procedures were similar in ABOi-RAKT, ABOc-RAKT, and ABOi-OKT groups. Recipient BMI at transplantation was statistically higher in ABOi and ABOc-RAKT groups compared to ABOi-OKT. The surgical site complication (principally infection-related) rate was lower in ABOi-RAKT, without statistical differences (0 vs. 8.9%, respectively, in ABOi-RAKT and ABOi-OKT, p = 0.7). The delayed graft function rate was 0% in ABOi-RAKT, 13.6% in ABOc-RAKT, and 10.7% in ABOi-OKT (p = 0.6). The post-transplantation blood transfusion rate was statistically higher in the ABOi-OKT group (14.3 vs. 13.6 vs. 57.1% in ABOi-RAKT, ABOc-RAKT, and ABOi-OKT, respectively, p = 0.001). The kidney graft survival at 1 month and at last follow-up was not different between ABOi-RAKT and ABOi-OKT.

Conclusion: Our data support the use of ABOi-RAKT to restore accessibility to kidney transplantation for obese patients to the greatest extent possible. Large series are required to confirm these encouraging data from a single center.

Obesity, transplantation, and bariatric surgery: An evolving solution for a growing epidemic

The increasing obesity epidemic has major implications in the realm of transplantation. Patients with obesity face barriers in access to transplant and unique challenges in perioperative and postoperative outcomes. Because of comorbidities associated with obesity, along with the underlying end-stage organ disease leading to transplant candidacy, these patients may not even be referred for transplant evaluation, much less be waitlisted or actually undergo transplant. However, the use of bariatric surgery in this population can help optimize the transplant candidacy of patients with obesity and end-stage organ disease and improve perioperative and postoperative outcomes. We review the impact of obesity on kidney, liver, and cardiothoracic transplant candidates and recipients and explore potential interventions to address obesity in these populations.

Obesity: An Independent Predictor of Morbidity and Graft Loss after Kidney Transplantation

BACKGROUND

There is conflicting information on current medical and surgical complications associated with high body mass index (BMI) after kidney transplantation.

METHODS

In a single-center observational study, we analyzed the 5-year outcomes of all consecutive primary kidney transplant recipients between 2010 and 2015 based on BMI at the time of transplant.

RESULTS

There were 1,467 patients included in this study, distributed in the following groups based on BMI: underweight (n = 32, 2.2%), normal (n = 407, 27.7%), overweight (n = 477, 32.5%), grade I obesity (n = 387, 26.4%), grade II obesity (n = 155, 10.6%), and grade III obesity (n = 9, 0.6%). Obesity was associated with an increased incidence of delayed graft function (p = 0.008), length of stay (LOS, p = 0.03), 30-day surgical re-exploration (p = 0.02), and hospital readmission (p < 0.0001). Obesity was also associated with higher 1-year serum creatinine (p = 0.03) and increased 5-year incidence of cardiac events (p < 0.0001) and congestive heart failure (p < 0.0001). Multivariable Cox regression analyses determined grade III obesity (HR = 5.84, 95% CI: 1.40-24.36, p = 0.01), LOS >4 days (HR = 1.94, 95% CI: 1.19-3.18, p = 0.008), hospital readmission (HR = 2.25, 95% CI: 1.20-4.22, p = 0.01), 1-year serum creatinine >1.5 (HR = 1.95, 95% CI: 1.20-3.18, p = 0.007), and proteinuria (UPC) >1 g/g (HR = 1.85, 95% CI: 1.06-3.24, p = 0.03) as independent predictors of death-censored graft failure.

CONCLUSION

In the current era of renal transplant care, obesity is common, and high BMI remains associated with significant medical and surgical complications after transplant.

Trends in the Medical Complexity and Outcomes of Medicare-insured Patients Undergoing Kidney Transplant in the Years 1998-2014

BACKGROUND

Graft and patient survival following kidney transplant are improving. However, the drivers of this trend are unclear. To gain further insight, we set out to examine concurrent changes in pretransplant patient complexity, posttransplant survival, and cause-specific hospitalization.

METHODS

We identified 101 332 Medicare-insured patients who underwent their first kidney transplant in the United States between the years 1998 and 2014. We analyzed secular trends in (1) posttransplant patient and graft survival and (2) posttransplant hospitalization for cardiovascular disease, infection, and cancer using Cox models with year of kidney transplant as the primary exposure of interest.

RESULTS

Age, dialysis vintage, body mass index, and the prevalence of a number of baseline medical comorbidities increased during the study period. Despite these adverse changes in case mix, patient survival improved: the unadjusted and multivariable-adjusted hazard ratios (HRs) for death in 2014 (versus 1998) were 0.61 (confidence interval [CI], 0.52-0.73) and 0.46 (CI, 0.39-0.55), respectively. For graft failure excluding death with a functioning graft, the unadjusted and multivariable adjusted subdistribution HRs in 2014 versus 1998 were 0.4 (CI, 0.25-0.55) and 0.45 (CI, 0.3-0.6), respectively. There was a marked decrease in hospitalizations for cardiovascular disease following transplant between 1998 and 2011, subdistribution HR 0.51 (CI, 0.43-0.6). Hospitalization for infection remained unchanged, while cancer hospitalization increased modestly.

CONCLUSIONS

Medicare-insured patients undergoing kidney transplant became increasingly medically complex between 1998 and 2014. Despite this, both patient and graft survival improved during this period. A marked decrease in serious cardiovascular events likely contributed to this positive trend.

Robotic-assisted kidney transplantation in obese recipients compared to non-obese recipients: the European experience

PURPOSE

The main objective was to compare minor (Clavien I-II) and major (Clavien ≥ III) intra- and postoperative complications of living donor robotic assisted kidney transplantation (RAKT) in obese (≥ 30 kg/m² BMI), overweight (< 30/ ≥ 25 kg/m² BMI) and non-overweight recipients (< 25 kg/m² BMI).

METHODS

For the present retrospective study, we reviewed the multi-institutional ERUS-RAKT database to select consecutive living donor RAKT recipients. Functional outcomes, intra- and postoperative complications were compared between obese, overweight and non-overweight recipients.

RESULTS

169 living donor RAKTs were performed, by 10 surgeons, from July 2015 to September 2018 in the 8 European centers. 32 (18.9%) recipients were obese, 66 (39.1%) were overweight and 71 (42.0%) were non-overweight. Mean follow-up was 1.2 years. There were no major intra-operative complications in either study group. Conversion to open surgery occurred in 1 obese recipient, in 2 overweight recipients and no conversion occurred in non-overweight recipients (p = 0.3). Minor and major postoperative complications rates were similar in the 3 groups. At one-year of follow-up, median eGFR was similar in all groups [54 (45-60) versus 57 (46-70) versus 63 (49-78) ml/min/1.73 m² in obese, overweight and non-overweight recipient groups, respectively, p = 0.5]. Delayed graft function rate was similar in the 3 groups. Only the number of arteries was an independent predictive factor of suboptimal renal function at post-operative day 30 in the multivariate analysis.

CONCLUSION

RAKT in obese recipients is safe, compared to non-overweight recipients and yields very good function, when it performed at high-volume referral centers by highly trained transplant teams.

Is Body Mass Index a Significant Independent Risk Factor for Graft Failure and Patient Death in the Modern Immunosuppressive Era?

OBJECTIVES

Previous studies have shown that kidney transplant recipients with a high body mass index (BMI) have inferior graft and patient outcomes compared to patients with a lower BMI. We hypothesized that there would be secular improvements in outcomes among high BMI recipients. We used data from the United Network for Organ Sharing (UNOS) to determine whether obesity affects patient and graft outcomes following kidney transplantation in the modern immunosuppressive era.

METHODS

The study sample consisted of 69,749 recipients from 1987 to 1999 and 197,986 recipients from 2000 to 2016. BMI values were categorized into 11 tiers: below 18 kg/m², from 18 to 36 kg/m² at 2 kg/m²-unit increments, and above 36 kg/m². We created multivariate models to evaluate the independent effect of BMI on graft and patient outcomes, adjusting for factors known to affect graft success and patient survival.

RESULTS

Overall graft and patient survival has improved for all BMI categories. Cox regression modeling hazard ratios showed that the relative risk for graft loss, patient death, and patient death with a functioning graft in the modern immunosuppressive era (2000 to 2016) has significantly decreased compared to the earlier era (1987 to 1999), especially for living kidney transplant recipients.

CONCLUSIONS

The relative risk of graft failure and patient death with increasing BMI has appreciably decreased in the modern immunosuppressive era, especially for living donor transplant recipients. Withholding transplantation from patients with higher BMIs may no longer be justifiable on grounds of worse clinical outcomes.

Obesity After Kidney Transplantation-Results of a KTx360°Substudy

OBJECTIVE

There is solid evidence that kidney transplant (KTx) patients are susceptible to weight gain after transplantation. Post-transplantation obesity [body mass index (BMI) ≥ 30 kg/m2] seems to be associated with higher risks of hypertension, dyslipidemia, diabetes mellitus, and cardiovascular events, while there are contradicting findings regarding the association between obesity and mortality, graft failure after transplantation as well as other variables. We aimed to evaluate the course of weight after KTx and to assess the prevalence of post-transplant obesity in a large sample of German KTx patients. Further, we focused on potential associations between weight gain, obesity, and BMI after transplantation with sociodemographic, medical, psychological [levels of anxiety and depression measured with the Hospital Anxiety and Depression Scale (HADS)], and donation-specific variables.

METHODS

In a structured post-transplant care program 433 KTx patients were evaluated at Hannover Medical School. Information on the pre-transplant body weight/dry weight of dialysis patients was taken from the electronic patient charts. At post-transplant assessment body weight was measured in the transplant center. For statistical analyses, descriptive statistics, analyses of variance, tests for correlations, and regression analyses were used.

RESULTS

Mean age was 51.3 years, 59% were male and 26.3% had ≥12 years of school attendance. Regarding somatic conditions 6.0% were suffering from type 2 diabetes mellitus, 6.9% were affected by new-onset diabetes after transplantation (NODAT), and the mean estimated glomerular filtration rate (eGFR) was 47.7 ml/min/1.73m2. The prevalence rates of obesity before and after kidney transplantation were 14.8 and 19.9%, respectively. This represents an increase of 34%. Obesity after transplantation was associated with higher rates of type 2 diabetes mellitus and of NODAT. Additionally, there was an association between increasing pre-transplant as well as post-transplant BMI and decreasing eGFR. Higher age and female sex were associated with higher rates of post-transplant obesity.

CONCLUSIONS

Our results suggest that obesity represents a serious problem in KTx patients, especially regarding the association between increasing BMI and decreasing graft functioning (eGFR). However, this aspect is often overlooked and information on effective treatment options for these patients are scarce making further research on this topic necessary.

Metabolic Disorders with Kidney Transplant

Metabolic disorders are highly prevalent in kidney transplant candidates and recipients and can adversely affect post-transplant graft outcomes. Management of diabetes, hyperparathyroidism, and obesity presents distinct opportunities to optimize patients both before and after transplant as well as the ability to track objective data over time to assess a patient's ability to partner effectively with the health care team and adhere to complex treatment regimens. Optimization of these particular disorders can most dramatically decrease the risk of surgical and cardiovascular complications post-transplant. Approximately 60% of nondiabetic patients experience hyperglycemia in the immediate post-transplant phase. Multiple risk factors have been identified related to development of new onset diabetes after transplant, and it is estimated that upward of 7%-30% of patients will develop new onset diabetes within the first year post-transplant. There are a number of medications studied in the kidney transplant population for diabetes management, and recent data and the risks and benefits of each regimen should be optimized. Secondary hyperparathyroidism occurs in most patients with CKD and can persist after kidney transplant in up to 66% of patients, despite an initial decrease in parathyroid hormone levels. Parathyroidectomy and medical management are the options for treatment of secondary hyperparathyroidism, but there is no randomized, controlled trial providing clear recommendations for optimal management, and patient-specific factors should be considered. Obesity is the most common metabolic disorder affecting the transplant population in both the pre- and post-transplant phases of care. Not only does obesity have associations and interactions with comorbid illnesses, such as diabetes, dyslipidemia, and cardiovascular disease, all of which increase morbidity and mortality post-transplant, but it also is intimately inter-related with access to transplantation for patients with kidney failure. We review these metabolic disorders and their management, including data in patients with kidney transplants.

Impact of obesity on dialysis and transplant and its management

Obesity is increasing to unprecedented levels, including in the end-stage kidney disease population, where upwards of 60% of kidney transplant patients are overweight or obese. Obesity poses additional challenges to the care of the dialysis patient, including difficulties in creating vascular access and inserting Tenckhoff catheters, higher rates of catheter malfunction and peritonitis, the need for longer and/or more frequent dialysis (or peritoneal dialysis [PD] exchanges) to achieve adequate clearance, increased metabolic complications particularly with PD, and obesity is a barrier to kidney transplantation. In this article, we review special considerations in performing PD, hemodialysis and transplant in the obese patient, as well as the evidence behind medical and surgical management of obesity in dialysis patients.

Early Postoperative Complications and Outcomes of Kidney Transplantation in Moderately Obese Patients

BACKGROUND

Obese renal transplant recipients (body mass index [BMI] ≥30 kg/m²) are at risk of delayed graft function and postoperative complications, such as infections or delayed wound healing. There is also a tendency to exclude extremely obese patients from transplantation (KTx). Nonetheless, no association between obesity and increased mortality has been reported. The aim of this study is to evaluate the effect of BMI on the most common surgical and infectious complications after KTx.

MATERIALS AND METHODS

An observational study in 872 patients transplanted from 2010-2017 was conducted. Median BMI was 24.6 (13.9-34.3), and 8.3% of the group was obese. Patient records were searched for early postoperative complications: lymphocele or hematoma (>33 mL), urinary leakage, or urinary tract infection (UTI). Mann-Whitney U and χ² or Fisher exact tests were used. P < .05 was considered statistically significant. The study complies with the Helsinki Congress and the Istanbul Declaration.

RESULTS

Renal primary nonfunction was observed in 1.4% (12/872) of patients. Surgical or infectious complications occurred in 52.7% (453/860) of patients. No correlation between BMI and complication rate was noted. Complications were observed in 56.9% (41/72) of obese vs 52.3% (412/788) of nonobese patients (P = .448), including lymphocele in 15.3% vs 16.4% (P = .810), hematoma in 22.2% vs 19.2% (P = .530), urinary leakage in 1.4% vs 4.6% (P = .203), and UTI in 31.9% vs 32.9% (P = .873), respectively.

CONCLUSIONS

Recipient's BMI has no significant association with the most common surgical complications after KTx. There is no need to delay KTx in moderately obese patients.

Medical Contraindications to Transplant Listing in the USA: A Survey of Adult and Pediatric Heart, Kidney, Liver, and Lung Programs

INTRODUCTION

Listing practices for solid organ transplantation are variable across programs in the USA. To better characterize this variability, we performed a survey of psychosocial listing criteria for pediatric and adult heart, lung, liver, and kidney programs in the USA. In this manuscript, we report our results regarding listing practices with respect to obesity, advanced age, and HIV seropositivity.

METHODS

We performed an online, forced-choice survey of adult and pediatric heart, kidney, liver, and lung transplant programs in the USA.

RESULTS

Of 650 programs contacted, 343 submitted complete responses (response rate = 52.8%). Most programs have absolute contraindications to listing for BMI > 45 (adult: 67.5%; pediatric: 88.0%) and age > 80 (adult: 55.4%; pediatric: not relevant). Only 29.5% of adult programs and 25.7% of pediatric programs consider HIV seropositivity an absolute contraindication to listing. We found that there is variation in absolute contraindications to listing in adult programs among organ types for BMI > 45 (heart 89.8%, lung 92.3%, liver 49.1%, kidney 71.9%), age > 80 (heart 83.7%, lung 76.9%, liver 68.4%, kidney 29.2%), and HIV seropositivity (heart 30.6%, lung 59.0%, kidney 16.9%, liver 28.1%).

CONCLUSIONS

We argue that variability in listing enhances access to transplantation for potential recipients who have the ability to pursue workup at different centers by allowing different programs to have different risk thresholds. Programs should remain independent in listing practices, but because these practices differ, we recommend transparency in listing policies and informing patients of reasons for listing denial and alternative opportunities to seek listing at another program.

Obesity in kidney transplantation

The prevalence of obesity among patients with chronic kidney disease continues to increase as a reflection of the trend observed in the general population. Factors affecting the access to the waiting list and the transplantability of this specific population will be analysed. From observational studies, kidney transplantation in obese patients carries an increased risk of surgical complications compared to the nonobese population; therefore, many centres have been reluctant to proceed with transplantation, despite this treatment modality confers a survival advantage over dialysis. As a consequence, obese patients continue to face decreased access to the waiting list, with a lower likelihood of being transplanted and higher waiting times when compared to the nonobese candidates. In this review will be described the current strategies for treatment of obesity in different settings (pretransplant, at transplant and post-transplant). Obesity represents a risk factor for surgical complications but not a contraindication for kidney transplantation; outcomes could be greatly improved with its multidisciplinary and multimodal treatment. The modern technology with minimally invasive techniques, mainly using robotic platform, allows a reduction in the surgical complications rate, with graft and patient survival rates comparable to the nonobese counterpart.

Effects of body weight variation in obese kidney recipients: a retrospective cohort study

Background

Obese kidney allograft recipients have worse results in kidney transplantation (KT). However, there is lack of information regarding the effect of body mass index (BMI) variation after KT. The objective of the study was to evaluate the effects of body weight changes in obese kidney transplant recipients.

Methods

In this study we used data from the Catalan Renal Registry that included KT recipients from 1990 to 2011 (n = 5607). The annual change in post-transplantation BMI was calculated. The main outcome variables were delayed graft function (DGF), estimated glomerular filtration rate (eGFR) and patient and graft survival.

Results

Obesity was observed in 609 patients (10.9%) at the time of transplantation. The incidence of DGF was significantly higher in obese patients (40.4% versus 28.3%; P < 0.001). Baseline obesity was significantly associated with worse short- and long-term graft survival (P < 0.05) and worse graft function during the follow-up (P < 0.005). BMI variations in obese patients did not improve eGFR or graft or patient survival.

Conclusions

Our conclusion is that in obese patients, decreasing body weight after KT does not improve either short-term graft outcomes or long-term renal function.

Access to Kidney Transplantation after a Failed First Kidney Transplant and Associations with Patient and Allograft Survival: An Analysis of National Data to Inform Allocation Policy

BACKGROUND AND OBJECTIVES

Patients who have failed a transplant are at increased risk of repeat transplant failure. We determined access to transplantation and transplant outcomes in patients with and without a history of transplant failure.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

In this observational study of national data, the proportion of waitlisted patients and deceased donor transplant recipients with transplant failure was determined before and after the new kidney allocation system. Among patients initiating maintenance dialysis between May 1995 and December 2014, the likelihood of deceased donor transplantation was determined in patients with (n=27,459) and without (n=1,426,677) a history of transplant failure. Among transplant recipients, allograft survival, the duration of additional kidney replacement therapy required within 10 years of transplantation, and the association of transplantation versus dialysis with mortality was determined in patients with and without a history of transplant failure.

RESULTS

The proportion of waitlist candidates (mean 14%) and transplant recipients (mean 12%) with transplant failure did not increase after the new kidney allocation system. Among patients initiating maintenance dialysis, transplant-failure patients had a higher likelihood of transplantation (hazard ratio [HR], 1.16; 95% confidence interval [95% CI], 1.12 to 1.20; P<0.001). Among transplant recipients, transplant-failure patients had a higher likelihood of death-censored transplant failure (HR, 1.44; 95% CI, 1.34 to 1.54; P<0.001) and a greater need for additional kidney replacement therapy required within 10 years after transplantation (mean, 9.0; 95% CI, 5.4 to 12.6 versus mean, 2.1; 95% CI, 1.5 to 2.7 months). The association of transplantation versus dialysis with mortality was clinically similar in waitlisted patients with (HR, 0.32; 95% CI, 0.29 to 0.35; P<0.001) and without transplant failure (HR, 0.40; 95% CI, 0.39 to 0.41; P<0.001).

CONCLUSIONS

Transplant-failure patients initiating maintenance dialysis have a higher likelihood of transplantation than transplant-naïve patients. Despite inferior death-censored transplant survival, transplantation was associated with a similar reduction in the risk of death compared with treatment with dialysis in patients with and without a prior history of transplant failure.

Obesity in Kidney Transplantation: Impact on Transplant Candidates, Recipients, and Donors

Obesity is now common among children and adults who are kidney transplant candidates and recipients. It is associated with an increased risk of cardiovascular disease and kidney failure. This also pertains to potential living kidney donors with obesity. Obese patients with end-stage renal disease benefit from transplantation as do nonobese patients, but obesity is also associated with more risk. A complicating factor is that obesity is also associated with increased survival on maintenance dialysis in adults, but not in children. The assessment of obesity and body habitus should be individualized. Body mass index is a common but imperfect indicator of obesity. The medical management of obesity in renal failure patients is often unsuccessful. Bariatric surgery, specifically laparoscopic sleeve gastrectomy, can result in significant weight loss with reduced morbidity, but many patients do not agree to undergo this treatment. The best approach to manage obese transplant candidates and recipients is yet unresolved.

Obesity and bariatric intervention in patients with chronic renal disease

Obesity is associated with chronic metabolic conditions that directly and indirectly cause kidney parenchymal damage. A review of the literature was conducted to explore existing evidence of the relationship between obesity and chronic kidney disease as well as the role of bariatric surgery in improving access to kidney transplantation for patients with a high body mass index. The review showed no definitive evidence to support the use of a transplant eligibility cut-off parameter based solely on the body mass index. Moreover, in the pre-transplant scenario, the obesity paradox is associated with better patient survival among obese than non-obese patients, although promising results of bariatric surgery are emerging. However, until more information regarding improvement in outcomes for obese kidney transplant candidates is available, clinicians should focus on screening of the overall frailty condition of transplant candidates to ensure their eligibility and addition to the wait list.

The Evolution of Kidney Transplantation Surgery Into the Robotic Era and Its Prospects for Obese Recipients

Robotic-assisted kidney transplantation (RAKT) represents the most recent innovation in the evolution of kidney transplantation surgery. Vascular techniques enabling kidney transplantation have existed since the early 20th century and contributed to the first successful open kidney transplant procedure in 1954. Technical advances have since facilitated minimally invasive laparoscopic and robotic techniques in live-donor surgery, and subsequently for the recipient procedure. This review follows the development of surgical techniques for kidney transplantation, with a special focus on the advent of robotic-assisted transplantation because of its potential to facilitate transplantation of those deemed previously too obese to transplant by standard means. The different techniques, indications, advantages, disadvantages, and future directions of this approach will be explored in detail. Robot-assisted kidney transplantation may become the preferred means of transplanting morbidly obese recipients, although its availability to such recipients remains extremely limited and strategies targeting weight loss pretransplantation should never be abandoned in favor of a "RAKT-first" approach.

Obesity as a barrier to kidney transplantation: Time to eliminate the body weight bias?

There is clear evidence that survival rates following transplantation far exceed those for remaining on dialysis, regardless of body size measured by body mass index (BMI). Studies over the past 15 years also suggest little to no difference in long-term outcomes, including graft survival and mortality, irrespective of BMI, in contrast to earlier evidence. However, weight bias still exists, as access to kidney transplantation remains inequitable in centers using arbitrary BMI limits. Clinicians faced with the decision regarding listing based on body size are not helped by conflicting recommendations in national and international guidelines. Therefore, in clinical practice, obesity, and recommendations for weight loss, remain a controversial issue when assessing suitability for kidney transplantation. Obesity management interventions in end-stage kidney disease (ESKD), whether for weight loss for transplantation listing or for slowing kidney disease progression, are under-explored in trial settings. Bariatric surgery is the most successful treatment for obesity, but carries increased risk in the ESKD population, and the desired outcome of kidney transplant listing is not guaranteed. Centers that limit transplants to those meeting arbitrary levels of body mass, rather than adopting an individualized assessment approach, may be unfairly depriving many ESKD patients of the survival and quality of life benefits derived from kidney transplantation. However, robotic kidney transplantation surgery holds promise for reducing perioperative risks related to obesity, and may therefore represent an opportunity to remove listing criteria based on size.

Weight management strategies for those with chronic kidney disease: A consensus report from the Asia Pacific Society of Nephrology and Australia and New Zealand Society of Nephrology 2016 renal dietitians meeting

AIM

The aim of the present study was to develop a consensus report to guide dietetic management of overweight or obese individuals with chronic kidney disease (CKD).

METHODS

Six statements relating to weight management in CKD guided a comprehensive review of the literature. A summary of the evidence was then presented at the renal nutrition meeting of the 2016 Asia Pacific Society of Nephrology and Australia and New Zealand Society of Nephrology. Majority agreement was defined as group agreement on a statement of between 50-74%, and consensus was considered ≥75% agreement. The recommendations were developed via a mini Delphi process.

RESULTS

Two statements achieved group consensus: the current guidelines used by dietitians to estimate energy requirements for overweight and obese people with CKD are not relevant and weight loss medications may be unsafe or ineffective in isolation for those with CKD. One statement achieved group agreement: Meal replacement formulas are safe and efficacious in those with CKD. No agreement was achieved on the statements of whether there is strong evidence of benefit for weight loss prior to kidney transplantation; whether traditional weight loss strategies can be used in those with CKD and if bariatric surgery in those with end stage kidney disease is feasible and effective.

CONCLUSION

There is a limited evidence base to guide the dietetic management of overweight and obese individuals with CKD. Medical or surgical strategies to facilitate weight loss are not recommended in isolation and require a multidisciplinary approach with the involvement of a skilled renal dietitian.

Baseline living-donor kidney volume and function associate with 1-year post-nephrectomy kidney function

Living donors may develop kidney dysfunction more often than equally healthy populations. The purpose of this study was to determine whether computed tomography-assessed remaining kidney volume indexed to body surface area (RKV/BSA) was associated with 1-year post-nephrectomy renal function independent of baseline renal function. Using multivariable regression, we modeled 1-year estimated glomerular filtration rate (eGFR) and eGFR <60 mL /min/1.73 m2 and considered pre-determined baseline eGFR subgroups in 151 consecutive donors. Mean ± SD baseline age, eGFR, RKV, BSA, and RKV/BSA were 38 ± 11 years, 97 ± 16 mL/min/1.73 m2 , 153 ± 29 mL, 1.9 ± 0.2 m2 , and 80.0 ± 12.8 ml/m2 , respectively; 50% were female and 94% were white. Mean baseline eGFR was greater with increasing RKV/BSA tertiles (92 ± 14, 97 ± 16, 107 ± 16 mL/min/1.73 m2 ; P < 0.001). Post-nephrectomy eGFR remained separated by RKV/BSA tertiles. At baseline, each SD greater RKV/BSA and eGFR was independently associated with higher adjusted 1-year eGFR by 2.4 and 9.2 mL/min/1.73 m2 . Each SD greater age associated with 2.2 mL/min/1.73 m2 lower adjusted 1-year eGFR. Adjusted odds of 1-year eGFR <60 increased significantly for donors with RKV/BSA <80 mL/m2 . With baseline eGFR <90, probability of 1-year eGFR <60 increased to >80% with decreasing RKV/BSA values below 80 mL/m2 . Those with baseline eGFR >100 rarely developed 1-year eGFR <60 if RKV/BSA remained >60 mL/m2 . RKV/BSA independently associated with 1-year eGFR <60, especially with lower baseline eGFRs. Additional studies should evaluate the predictive utility of this measure and its potential role in donor evaluations and informed consent.

Renal Transplant in Obese Patients and Impact of Weight Loss Before Surgery on Surgical and Medical Outcomes: A Single-Center Cohort Study

OBJECTIVES

Previous studies have linked obesity to poor outcomes in renal transplant recipients, prompting many transplant centers to encourage weight loss pretransplant in obese patients. Here, we performed a single-center retrospective study to assess the effects of weight loss on graft and patient outcomes.

MATERIALS AND METHODS

Data from 893 renal transplant recipients at our center from 2007 to 2011 were analyzed. First, renal transplant recipients with a history of obesity before transplant (42%) were compared with nonobese patients. Second, in the obese group, renal transplant recipients with significant weight loss (> 10%) before transplant were compared with other obese renal transplant recipients without significant weight loss.

RESULTS

Renal transplant recipients were predominantly white, with 74% having undergone living-donor transplant. Obese patients were older (56.6 vs 46.7 y old) and had more comorbidities and more surgical complications, in particular wound complications and incisional hernias, posttransplant than nonobese patients (14.7 vs 5.5%, respectively). Patient and graft survival rates were similar to those in nonobese patients. In the obese group, patient characteristics and medical or surgical complications after transplant did not differ between those with or without significant weight loss. However, obese patient and graft survival rates were lower in patients with weight loss than in obese patients without weight loss.

CONCLUSIONS

In our study, weight loss before transplant surgery in obese patients had no influence on surgical outcomes but was associated with a higher mortality rate. A prospective assessment of the impact of weight loss before surgery is needed to establish its usefulness.

The Incidence and Pathophysiology of the Obesity Paradox: Should Peritoneal Dialysis and Kidney Transplant Be Offered to Patients with Obesity and End-Stage Renal Disease?

PURPOSE OF REVIEW

To educate nephrologists and primary-care physicians about the incidence, pathophysiology, and survival benefits of the obesity paradox in end-stage renal disease (ESRD). This review also discusses the future of kidney transplant and peritoneal dialysis in obese dialysis patients.

RECENT FINDINGS

Obesity paradox in ESRD was first reported three decades ago, and since then, there have been several epidemiological studies that confirmed the phenomenon. Regardless of the anthropometric indices used to define obesity in ESRD patients, these markers serve to predict the dialysis patient's survival. The pathophysiology of obesity paradox tends to be multifactorial. Recent cohort studies demonstrated a survival benefit in all race and ethnic groups, but Hispanics and blacks experienced increased survival rates when compared to non-Hispanic whites. Obese dialysis patients should be offered peritoneal dialysis, especially if they are new to dialysis and have an adequate renal residual function. Several studies have shown that the benefit of receiving kidney transplant in obese patients exceeds the risks. The robotic-assisted kidney transplant (RAKT) procedure is the latest innovation that could offer hope for obese dialysis patients who have been denied or are waiting for kidney transplant. The obesity paradox phenomenon in ESRD is a unique illustration of survival benefit in a population that has a high overall annual mortality. Peritoneal dialysis should be encouraged for obese patients who have preserved residual renal function. Kidney transplant centers should encourage RAKT utilization in obese dialysis patients instead of denying them a kidney transplant.

Is big bad or bearable? Long-term renal transplant outcomes in obese recipients

BACKGROUND

The global obesity epidemic has implications for kidney transplantation. There are conflicting reports regarding the impact of obesity on long-term post-transplant outcomes.

AIM

To explore the impact of body mass index (BMI) on long-term outcomes after kidney transplantation.

DESIGN

The association between BMI and cardiovascular disease, cancer, post-transplant diabetes mellitus, graft and recipient survival was investigated in recipients who had been transplanted at least ten years previously.

METHODS

All consecutive adult renal transplant recipients who received first, deceased donor, transplants between 1986 and 2005 in Northern Ireland were followed-up until 2016.

RESULTS

A total of 328 patients were eligible. Of them, 96 were overweight with a BMI 25.0-29.9 kg/m2, and 56 were obese with a BMI exceeding 29.9 kg/m2. Median follow-up time was 16.7 years. In multivariate analysis recipient BMI was associated with the development of post-transplant diabetes mellitus (P=0.003), but not with new cardiovascular disease (P=0.78). Cancer was less common in recipients with a higher BMI (hazard ratio (HR) 0.58, P < 0.001). BMI at the time of transplantation did not significantly influence graft (P=0.28) or recipient survival (P=0.13).

CONCLUSIONS

Increased BMI at time of transplantation is associated with an increased risk of post-transplant diabetes mellitus but not new cardiovascular disease or malignancy. Long-term graft and recipient survival is not impacted. Potential recipients should not be excluded from transplantation solely on the basis of obesity, rather it should be considered as one part of an individualized risk stratification, based on comorbidity and considering the risk of death on maintenance dialysis.

Roux-en-Y gastric bypass is an effective bridge to kidney transplantation: Results from a single center

Body mass index (BMI) > 35-40 kg/m² is often a contraindication, while Roux-en-Y gastric bypass (RYGB) is performed to enable kidney transplantation. This single-center retrospective study evaluated pre- and post-transplant outcomes of 31 morbidly obese patients with end-stage renal disease having RYGB before kidney transplantation between July 2009 and June 2014. Fourteen RYGB patients were subsequently transplanted. Nineteen recipients not having GB with a BMI ≥ 36 kg/m² at transplantation were used as historical controls. Mean BMI (±SE) before RYGB was 43.5 ± 0.7 kg/m² (range: 35.4-50.5 kg/m² ); 87.1% (27/31) achieved a BMI < 35 kg/m² . The percentage having improved diabetes/hypertension control was 29.0% (9/31); 25.8% (8/31) had complications (mostly minor) after RYGB. Among transplanted patients, blacks/Hispanics comprised 78.6% (11/14) and 84.2% (16/19) of RYGB and controls; 57.1% (8/14) and 63.2% (12/19) had a (mostly long-standing) pretransplant history of diabetes. While biopsy-proven acute rejection (BPAR) occurred significantly higher among RYGB vs control patients (6/14 vs 3/19, P = .03), patients developing T-cell BPAR were also significantly more likely to have a tacrolimus (TAC) trough level < 4.0 ng/mL within 3 weeks of T-cell BPAR (P = .0007). In Cox's model, the impact of having a TAC level < 4.0 ng/mg remained significant (P = .007) while the effect of RYGB was no longer significant (P = .13). Infections, graft, and patient survival were not significantly different. Despite obvious effectiveness in achieving weight loss, RYGB will need more careful post-transplant monitoring given the observed higher BPAR rate.