Obesity and kidney transplant candidates: how big is too big for transplantation?

Open Renal Transplantation in Obese Patients: A Correlation Study between BMI and Early and Late Complications with Implementation of a Prognostic Risk Score

BACKGROUND

Obesity is a global epidemic that affects millions worldwide and can be a deterrent to surgical procedures in the population waiting for kidney transplantation. However, the literature on the topic is controversial. This study evaluates the impact of body mass index (BMI) on complications after renal transplantation, and identifies factors associated with major complications to develop a prognostic risk score.

METHODS

A correlation analysis between BMI and early and late complications was first performed, followed by a univariate and multivariate logistic regression analysis. The 302 included patients were divided into obese (BMI ≥ 30 kg/m2) and non-obese (BMI ≤ 30 kg/m2) groups. Correlation analysis showed that delayed graft function (DGF) was the only obesity-associated complication (p = 0.044). Logistic regression analysis identified female sex, age ≥ 57 years, BMI ≥ 25 and ≥30 kg/m2, previous abdominal and/or urinary system surgery, and Charlson morbidity Score ≥ 3 as risk factors for significant complications. Based on the analyzed data, we developed a nomogram and a prognostic risk score.

RESULTS

The model's area (AUC) was 0.6457 (95% IC: 0.57; 0.72). The percentage of cases correctly identified by this model retrospectively applied to the entire cohort was 73.61%.

CONCLUSIONS

A high BMI seems to be associated with an increased risk of DGF, but it does not appear to be a risk factor for other complications. Using an easy-to-use model, identification, and stratification of individualized risk factors could help to identify the need for interventions and, thus, improve patient eligibility and transplant outcomes. This could also contribute to maintaining an approach with high ethical standards.

Approach to weight management in patients with advanced chronic kidney disease in a real-life clinical setting

Objective

Excess adiposity represents a risk factor for chronic kidney disease (CKD) and progression to end-stage kidney disease. Anti-Obesity Medications (AOMs) are vastly underutilized in patients with advanced CKD because of concerns related to safety and efficacy. This study was conducted to evaluate the real-world approach to weight management and the efficacy and safety of AOMs in people with advanced CKD.

Methods

This is a retrospective analysis of individuals with Body Mass Index (BMI) ≥ 27 kg/m2 and eGFR ≤ 30 mL/min/1.73 m2 referred to an academic medical weight-management program between 01/2015 and 09/2022. Evaluation of weight-management approaches, body weight change, treatment-related side effects, and reasons for treatment discontinuation were reported.

Results

Eighty-nine patients met inclusion criteria, 16 were treated with intensive lifestyle modifications (ILM) alone and 73 with AOMs (all treated with glucagon-like peptide-1 receptor agonist [GLP1-RA] +/- other AOMs) along with ILM. Patients treated with AOMs had a longer duration of on-treatment follow-up (median 924 days) compared to (93 days) the ILM group. Over 75% of patients treated with AOMs lost ≥5% body weight versus 25% of those treated with ILM. Only 15% of patients treated with AOMs discontinued therapy due to treatment-related side effects.

Conclusion

In patients with obesity and advanced CKD, GLP-1RA-based anti-obesity treatment was well-tolerated, effective, and led to durable weight reduction.

Elements of Weight Management Among Pre-Kidney Transplant Candidates: The Patient Perspective

Obesity and related comorbidities heighten risks for complications in kidney transplant settings. While pre-transplant patients often have access to nutrition counseling and health support, literature is limited on patients' perceptions of weight and motivation to lose weight prior to transplantation. We conducted a survey among ≥18-year-old patients on the kidney transplant waitlist at a single center. Questions addressed weight perception, motivation for weight loss, available resources, and engagement in physical activity. Medical records provided demographic and clinical data. Statistical tests analyzed quantitative data, while free-text responses were thematically grouped and described. Of 1055 patients, 291 responded and were matched with demographic data. Perceived weight changes correlated with actual changes in body mass index (BMI) (<24.9) were more receptive to weight center resources (<30 kg/m2) are most interested in weight loss resources and demonstrate motivation. Furthermore, pre-transplant nutrition counseling correlates with healthier behaviors. Integrating patients' perspectives enhances pre-transplant protocols by encouraging active involvement in health decisions.

Patient-Level and Center-Level Factors Associated with Required Predonation Weight Loss among Obese Living Kidney Donors

Key Points

Among obese living kidney donors, year of donation, preoperative body mass index, hypertension, and center percent of living kidney donor transplants were associated with required predonation weight loss. There were no significant differences in the likelihood of predonation weight loss requirement by race, sex, or age or by markers of preoperative metabolic dysfunction.

Background

The proportion of overweight/mildly obese living kidney donors (OLKDs) has increased in the past few decades, with significant center variation in the body mass index (BMI) of LKDs. The purpose of this study was to examine factors associated with required predonation weight loss among OLKDs (BMI, ≥30 kg/m2).

Methods

This retrospective cohort study surveyed 1097 OLKDs (1979–2020) (mean BMI, 33 kg/m2) about their donation experience. Bivariate analyses compared donor demographic and center characteristics by whether the donor reported predonation weight loss requirement. Generalized estimating equations with logit link were used to estimate marginal effects of patient-level and center-level factors. Multiple imputation using chained equations was implemented to account for missing values.

Results

Of 1097 OLKDs surveyed, 340 (31.0%) reported predonation weight loss requirement. Donors with a predonation weight loss requirement had slightly higher predonation BMIs and donated in more recent years at centers performing a lower percentage of living donor nephrectomies and with a lower median BMI. In multivariable logistic regression analysis, we observed transplant year (odds ratio [OR], 1.04 per year donation; 95% confidence interval [CI], 1.01 to 1.07; P = 0.005), preoperative BMI (OR, 1.16; 95% CI, 1.05 to 1.28; P < 0.01), preoperative hypertension (OR, 1.61; 95% CI, 1.08 to 2.40; P = 0.02), and center percentage of living donor kidney transplants (OR, 0.99; 95% CI, 0.98 to 1.00; P = 0.02) as significantly associated with a predonation weight loss requirement. The study found no differences in the likelihood of predonation weight loss requirement by race, sex, age, preoperative creatinine, preoperative metabolic dysfunction, or center-level median BMI of living donors.

Conclusions

These results suggest that both center-level and patient-level factors influence whether OLKDs are required to lose weight before donation. Future study is needed to determine whether predonation weight loss is associated with improved long-term postdonation outcomes.

Management of pediatric obesity as a pathway towards kidney transplantation

Obesity is an increasing problem in pediatrics, leading to cardiovascular, metabolic and psychosocial complications. Additionally, for patients with chronic kidney disease (CKD), obesity can lead to CKD progression towards end-stage renal disease (ESRD) needing renal-replacement therapy (RRT). It is well-established that the optimal type of RRT for children with ESRD is kidney transplantation, as it provides significantly better life expectancy and quality of life. Unfortunately, pediatric patients with CKD/ESRD and obesity face barriers getting to kidney transplantation and often remain on dialysis for a long time, which negatively impacts their life expectancy and quality of life. One barrier to kidney transplant is that Body Mass Index (BMI) is still considered by most transplant centers as the main criterion for obesity assessment, although more recent evidence suggests that BMI is not the best measure of adiposity. Clearcut evidence is lacking that obesity has a long-term negative impact upon the graft. Another barrier to transplant can be bias on the part of referring providers that can deter or delay referral to an obesity treatment program. Our article describes the barriers that pediatric obese patients with CKD and ESRD face in their way towards kidney transplantation. In addition, our article encourages pediatric nephrologists to early refer their patients with CKD and ESRD who suffer from obesity to a specialized obesity treatment program and/or bariatric surgery. Our article also describes the treatment options for pediatric patients with CKD and ESRD who suffer from obesity in order to make them eligible for a kidney transplant.

Effect of Recipient Body Mass Index on Kidney Transplantation Outcomes: A Systematic Review and Meta-analysis by the Transplant Committee from the French Association of Urology

CONTEXT

The impact of recipient obesity on kidney transplantation (KT) outcomes remains unclear.

OBJECTIVE

The aim of this study was to perform a systematic review and meta-analysis to appraise all available evidence on the outcomes of KT in obese patients (body mass index [BMI] ≥30 kg/m2) versus nonobese patients (BMI <30 kg/m2).

EVIDENCE ACQUISITION

A systematic review and meta-analysis was performed. Search was conducted in the MEDLINE OvidSP, Web of Science, Google Scholar, Embase, and Cochrane databases to identify all studies reporting the outcomes of KT in obese versus nonobese recipients.

EVIDENCE SYNTHESIS

Fifty-two articles met the inclusion criteria. Delayed graft function and surgical complications were significantly higher in obese recipients (delayed graft function: relative risk [RR]: 1.44, 95% confidence interval [CI]: 1.32-1.57, p < 0.01; surgical complications: RR: 1.74, 95% CI: 1.36-2.22, p < 0.0001). Five-year patient survival (RR: 0.96, 95% CI: 0.92-1.00, p = 0.01), 10-yr patient survival (RR: 0.90, 95% CI: 0.84-0.97, p = 0.006), and 10-yr graft survival (RR: 0.87, 95% CI: 0.79-0.96, p = 0.01) were significantly inferior in the obese group.

CONCLUSIONS

KT in obese recipients was associated with lower patient and graft survival, and higher delayed graft function, acute rejection, and medical and surgical complications than nonobese recipients. In the current situation of organ shortage and increasing prevalence of obesity, ways to optimize KT in this setting should be investigated.

PATIENT SUMMARY

Compared with nonobese population, kidney transplantation in obese recipients has inferior patient and graft survival, and higher medical and surgical complications.

Findings of Cardiovascular Workup of Kidney Transplant Candidates: A Retrospective Study of a Single-Center in Saudi Arabia

Background

There are limited data about the prevalence of cardiovascular (CV) risk factors and the findings of CV workup among kidney transplant (KTx) recipients (KTRs) in Saudi Arabia.

Methods

A single-center retrospective study of KTRs who underwent KTx from 2017 to 2020 was performed. We reviewed the prevalence of CV risk factors and the results of the pre-KTx CV workup which was derived from the American Heart Association guidelines.

Results

We included 254 KTRs. The mean age was 43.1 ± 15.9 years, and 55.5% were men and 79.5% were living-donor KTRs. Pre-emptive KTx was 9.8%, peritoneal dialysis was 11.8%, and hemodialysis was 78.3% (arteriovenous fistula: 33.1% versus hemodialysis catheter: 66.9%). The mean dialysis vintage was 4.8 ± 3.3 years for deceased-donor KTRs versus 2.4 ± 2.6 years for living-donor KTRs. CV risk factors were hypertension: 76%, diabetes: 40.6% (type 1 : 25.2% versus type 2 : 74.7%), hyperlipidemia (low-density lipoprotein >2.6 mmol/L): 40.2%, coronary artery disease (CAD): 12.6%, smoking: 9.1%, peripheral vascular disease: 2.8%, and cerebral vascular disease: 2.4%. The prevalence of obesity stage 1 was 19.7% and obesity stage 2 was 4%. Left ventricular hypertrophy was present in 38.5%. The ejection fraction was abnormal (<55%) in 22%. Abnormal wall motion was present in 34 patients (13.4%). A cardiac (PET-CT) stress test was conducted on 129 patients (50.8%) which showed abnormal perfusion in 37 patients (28.7%). Out of those who required PET-CT, 18.6% had a coronary artery calcium scoring (CACS) of more than 400, 41.8% had a CACS of zero, 29.4% had a CACS of 1-100, and 14.7% had a CACS of 100-400. Coronary angiogram was required in only 41 patients (16.1%), 12 (29.3%) required coronary interventions, 25 (61%) were treated medically, and 4 (9.8%) did not have any CAD. CT scans of pelvic arteries were performed in 118 patients (46.5%). It showed moderate or severe calcifications in only 7 patients (5.9%), whereas it was normal in 97 patients (82.2%), or it showed only mild calcifications in 14 patients (11.9%).

Conclusion

This study outlines the prevalence of CV risk factors and the findings of the pretransplant CV workup among KTx candidates who underwent KTx. Multicenter national studies will be helpful to validate the generalizability of these findings.

Findings of Cardiovascular Workup of Kidney Transplant Candidates: A Retrospective Study of a Single-Center in Saudi Arabia.. [DOI: 10.21203/rs.3.rs-3030184/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

Background: There are limited data about the prevalence of cardiovascular (CV) risk factors and the findings of CV workup among kidney transplant (KTx) recipients (KTRs) in Saudi Arabia. Method: A single-center retrospective study of KTRs who underwent KTx from 2017 to 2020. We reviewed the prevalence of CV risk factors and the results of the pre-KTx CV workup which was derived from the American Heart Association guidelines. Results: We included 254 KTRs. The mean age was 43.1±15.9 years, 55.5% were men and 79.5% were living-donor KTRs. Pre-emptive KTx was 9.8%, peritoneal dialysis: 11.8% and hemodialysis: 78.3% (arteriovenous fistula: 33.1% versus hemodialysis catheter: 66.9%). Mean dialysis vintage was 4.8±3.3 years for deceased-donor KTRs versus 2.4±2.6 years for living-donor KTRs. CV risk factors were hypertension: 76%, diabetes: 40.6% (type 1: 25.2% versus type 2: 74.7%), hyperlipemia (low-density lipoprotein> 2.6 mmol/L): 40.2%, coronary artery disease (CAD): 12.6%, smoking: 9.1%, peripheral vascular disease: 2.8%, and cerebral vascular disease: 2.4%. The prevalence of obesity stage 1 was 19.7% and obesity stage 2 was 4%. Left ventricular hypertrophy was present in 38.5%. Ejection fraction was abnormal (<55%) in 22%. Abnormal wall motion was present in 34 patients (13.4%). Cardiac (PET-CT) stress test was indicated in 129 patients (50.8%) and showed abnormal perfusion in 37 patients (28.7%). Out of those who required PET-CT, 18.6% had coronary artery calcium scoring (CACS) more than 400, 41.8 had CACS of zero, 29.4% had CACS of 1-100, and 14.7% had CACS of 100-400. Coronary angiogram was required in only 41 patients (16.1%), 12 (29.3%) required coronary interventions, 25 (61%) were treated medically, and 4 (9.8%) did not have any CAD. CT scans of pelvic arteries were performed in 118 patients (46.5%). It showed moderate or severe calcifications in only 7 patients (5.9%), whereas it was normal in 97 patients (82.2%), or it showed only mild calcifications in 14 patients (11.9%). Conclusion: This study outlines the prevalence of CV risk factors and the findings of the pretransplant CV workup among KTx candidates who underwent KTx. Multicenter national studies will be helpful to validate the generalizability of these findings.

Post-kidney transplant body mass index trajectories are associated with graft loss and mortality

BACKGROUND

Early post-kidney transplantation (KT) changes in physiology, medications, and health stressors likely impact body mass index (BMI) and likely impact all-cause graft loss and mortality.

METHODS

We estimated 5-year post-KT (n = 151 170; SRTR) BMI trajectories using an adjusted mixed effects model. We estimated long-term mortality and graft loss risks by 1-year BMI change quartile (decrease [1st quartile]: change < -.07 kg/m2 /month; stable [2nd quartile]: -.07 ≤ change ≤ .09 kg/m2 /month; increase [3rd, 4th quartile]: change > .09 kg/m2 /month) using adjusted Cox proportional hazards models.

RESULTS

BMI increased in the 3 years post-KT (.64 kg/m2 /year, 95% CI: .63, .64) and decreased in years 3-5 (-.24 kg/m2 /year, 95% CI: -.26, -.22). 1-year post-KT BMI decrease was associated with elevated risks of all-cause mortality (aHR = 1.13, 95% CI: 1.10-1.16), all-cause graft loss (aHR = 1.13, 95% CI: 1.10-1.15), death-censored graft loss (aHR = 1.15, 95% CI: 1.11-1.19), and mortality with functioning graft (aHR = 1.11, 95% CI: 1.08-1.14). Among recipients with obesity (pre-KT BMI≥30 kg/m2 ), BMI increase was associated with higher all-cause mortality (aHR = 1.09, 95% CI: 1.05-1.14), all-cause graft loss (aHR = 1.05, 95% CI: 1.01-1.09), and mortality with functioning graft (aHR = 1.10, 95% CI: 1.05-1.15) risks, but not death-censored graft loss risks, relative to stable weight. Among individuals without obesity, BMI increase was associated with lower all-cause graft loss (aHR = .97, 95% CI: .95-.99) and death-censored graft loss (aHR = .93, 95% CI: .90-.96) risks, but not all-cause mortality or mortality with functioning graft risks.

CONCLUSIONS

BMI increases in the 3 years post-KT, then decreases in years 3-5. BMI loss in all adult KT recipients and BMI gain in those with obesity should be carefully monitored post-KT.

The Fat Kidney

PURPOSE OF REVIEW

The purpose of this review is to summarize the current evidence on the role of obesity in the development and progression of chronic kidney disease and the current evidence on nutritional, pharmacological, and surgical strategies for the management of individuals with obesity and chronic kidney disease.

RECENT FINDINGS

Obesity can hurt the kidney via direct pathways, through the production of pro-inflammatory adipocytokines, and indirectly due to systemic complications of obesity, including type 2 diabetes mellitus and hypertension. In particular, obesity can damage the kidney through alterations in renal hemodynamics resulting in glomerular hyperfiltration, proteinuria and, finally, impairment in glomerular filtratation rate. Several strategies are available for weight loss and maintenance, such as the modification of lifestyle (diet and physical activity), anti-obesity drugs, and surgery therapy, but there are no clinical practice guidelines to manage subjects with obesity and chronic kidney disease. Obesity is an independent risk factor for the progression of chronic kidney disease. In subjects with obesity, weight loss can slow down the progression of renal failure with a significant reduction in proteinuria and improvement in glomerular filtratation rate. Specifically, in the management of subjects with obesity and chronic renal disease, it has been shown that bariatric surgery can prevent the decline in renal function, while further clinical studies are needed to evaluate the efficacy and safety on the kidney of weight reducing agents and the very low-calorie ketogenic diet.

Pretransplant BMI Should Be <25 in Japanese Kidney Transplant Recipients: A Single-Center Experience

BACKGROUND

The aim of this study was to determine the appropriate body mass index (BMI) in Japanese kidney transplant (KTx) recipients. We analyzed the effects of pre- and post-transplant (Tx) obesity on graft and patient survival, perioperative complications, post-transplant diabetes mellitus (PTDM), and cardiovascular disease (CVD) in Japanese KTx recipients.

METHODS

This retrospective study included 269 recipients who underwent KTx from 2008 through 2020 at Niigata University Hospital. Obesity was defined as a body mass index (BMI) ≥25 kg/m². We examined the association between pre- and post-Tx obesity and graft survival, patient survival, the incidence of PTDM and CVD, and perioperative surgical complications.

RESULTS

The graft survival rate was lower in the pre-Tx BMI ≥25 kg/m² group, although there was no significant difference in patient survival. There was no difference in graft and patient survival between the post-Tx BMI ≥25 kg/m² group and the <25 kg/m² group. A pre-Tx BMI ≥25 kg/m² was an independent risk factor for biopsy-proven allograft rejection. New-onset DM after transplantation was significantly more common in the BMI ≥25 kg/m² group than in the BMI <25 kg/m² group (36% vs 13%; P = .002). The incidence of CVD was significantly higher in the post-Tx BMI ≥30 kg/m² group than in the BMI <30 kg/m² group (50% vs 11%; P = .023). There were no differences in surgical operating time, intraoperative blood loss, or perioperative complications between the obese and non-obese groups.

CONCLUSION

Pre-Tx BMI ≥25 kg/m² may be a risk factor for allograft rejection and graft loss. Post-Tx BMI should be <25 kg/m² to reduce the risk for PTDM.

Cognitive-behavioral and dietary weight loss intervention in adult kidney transplant recipients with overweight and obesity: Results of a pilot RCT study (Adi-KTx)

The obesity epidemic and its health consequences have not spared the population of kidney transplant (KTx) candidates and recipients. In addition, KTx recipients are susceptible to weight gain after transplantation. Overweight and obesity after KTx are strongly associated with adverse outcomes. Therefore, we designed a randomized controlled, mono-center study to specifically test the effectiveness of a primarily cognitive-behavioral approach supplemented by nutritional counseling for weight reduction following KTx as the intervention group (IG) in comparison to a brief self-guided intervention as control group (CG). The study was registered in the German Clinical Trials Register (DRKS-ID: DRKS00017226). Fifty-six KTx patients with a BMI from 27 to 40 kg/m² were included in this study and randomized to the IG or CG. Main outcome was the number of participants achieving a 5% weight loss during the treatment phase. Additionally, participants were assessed 6 and 12 months after the end of the 6-month treatment phase. Participants significantly lost weight without group differences. 32.0% (n = 8) of the patients in the IG and 16.7% (n = 4) of the patients in the CG achieved a weight loss of 5% or more. Weight loss was largely maintained during follow-up. Retention and acceptance rate in the IG was high, with 25 (out of 28) patients completing all 12 sessions and one patient completing 11 sessions. Short-term, cognitive-behaviorally oriented weight loss treatment seems to be feasible and acceptable for patients after KTx who suffer from overweight or obesity. This clinical trial was ongoing at the onset of the COVID-19 pandemic which might have influenced study conduct and results. Clinical Trial Registration: https://clinicaltrials.gov/ DRKS-ID: DRKS00017226.

Preoperative blood pressure and risk of delayed graft function in deceased donor kidney transplantation

BACKGROUND

In kidney transplantation, delayed graft function (DGF) is associated with increased morbidity and a higher risk of graft failure. Prior research suggests that chronic hypotension increases DGF risk, but the relationship of preoperative blood pressure to DGF is unclear.

METHODS

In this single center study of adult deceased donor kidney transplant recipients transplanted between 2015 and 2019, we evaluated the question of whether preoperative mean arterial pressure (MAP) affected DGF risk. Additionally, we investigated whether the risk of DGF was moderated by certain donor and recipient characteristics. For recipient characteristics associated with increased DGF risk and preoperative MAP, we performed a mediation analysis to estimate the proportion of DGF risk mediated through preoperative MAP.

RESULTS

Among 562 deceased donor kidney recipients, DGF risk decreased as preoperative MAP increased, with a 2% lower risk per 1 mm Hg increase in MAP. This increased risk was similar, with no statistically significant interaction effect between preoperative MAP and donor (donation after circulatory death) and recipient characteristics (diabetes, body mass index, and use of anti-hypertensive medications). Preoperative MAP was negativity correlated with recipient BMI and duration of pre transplant dialysis. On mediation analysis, MAP accounted for 12% and 16% of the DGF risk associated with recipient BMI and pre-transplant dialysis duration, respectively.

CONCLUSION

In deceased donor kidney transplantation, each 1 mm Hg increase in preoperative MAP was associated with 2% lower DGF risk. Preoperative MAP was influenced by recipient BMI and dialysis duration, and likely contributes to some of the high DGF risk from obesity and long dialysis vintage.

Pretransplant BMI Significantly Affects Perioperative Course and Graft Survival after Kidney Transplantation: A Retrospective Analysis

Background. The number of kidney transplant recipients (KTRs) with overweight and obesity is increasing. It was shown that obesity is related to inferior patient and graft survival. We aimed to analyze intraoperative parameters and postoperative short and long-term course of kidney transplantation (KT) in body mass index (BMI)-stratified cohorts of KTRs. Methods. A retrospective analysis of a prospectively built database of 433 KTRs from 2014 to 2017 from a single transplant center was performed. The objective of the study was to analyze the association between BMI at the time of transplantation with intraoperative parameters, adverse events in early postoperative course, and the overall mortality and graft loss in BMI-stratified cohorts: normal (18.5 and 24.9 kg/m2), overweight (25−29.9 kg/m2) and obese (≥30 kg/m2). Results. Obesity was related to longer total procedure time (p = 0.0025) and longer warm ischemia time (p = 0.0003). The postoperative course in obese patients was complicated by higher incidence of DGF (delayed graft function), early surgical complications (defined as surgical complications <30 days from KT), reoperation rate, vascular complications, incidence of lymphocele and wound dehiscence. There was no difference between the normal weight and overweight KTRs. The one-month kidney function (p = 0.0001) and allograft survival (p = 0.029) were significantly inferior in obese patients with no difference between normal weight and overweight patients. One-year death-censored graft survival was better in patients with BMI < 30 (88.6 vs. 94.8% p = 0.05). BMI was a significant predictor of graft loss in univariate (p = 0.04) but not in multivariate analysis (p = 0.09). Conclusion. Pretransplant obesity significantly affects the intraoperative and postoperative course of kidney transplantation and graft function and survival. The course of transplantation of overweight is comparable to normal BMI KTRs, and presumably pretransplant weight reduction to the BMI < 30 kg/m2 may improve the short-term postoperative course of transplantation as well as may improve graft survival. Thus, pretransplant weight reduction in obese KTRs may significantly improve the results of kidney transplantation. Metabolic surgery may play a role in improving results of KT.

Machine Learning Consensus Clustering of Morbidly Obese Kidney Transplant Recipients in the United States

Background: This study aimed to better characterize morbidly obese kidney transplant recipients, their clinical characteristics, and outcomes by using an unsupervised machine learning approach. Methods: Consensus cluster analysis was applied to OPTN/UNOS data from 2010 to 2019 based on recipient, donor, and transplant characteristics in kidney transplant recipients with a pre-transplant BMI ≥ 40 kg/m2. Key cluster characteristics were identified using the standardized mean difference. Post-transplant outcomes, including death-censored graft failure, patient death, and acute allograft rejection, were compared among the clusters. Results: Consensus clustering analysis identified 3204 kidney transplant recipients with a BMI ≥ 40 kg/m2. In this cohort, five clinically distinct clusters were identified. Cluster 1 recipients were predominantly white and non-sensitized, had a short dialysis time or were preemptive, and were more likely to receive living donor kidney transplants. Cluster 2 recipients were older and diabetic. They were likely to have been on dialysis >3 years and receive a standard KDPI deceased donor kidney. Cluster 3 recipients were young, black, and had kidney disease secondary to hypertension or glomerular disease. Cluster 3 recipients had >3 years of dialysis and received non-ECD, young, deceased donor kidney transplants with a KDPI < 85%. Cluster 4 recipients were diabetic with variable dialysis duration who either received non-ECD standard KDPI kidneys or living donor kidney transplants. Cluster 5 recipients were young retransplants that were sensitized. One-year patient survival in clusters 1, 2, 3, 4, and 5 was 98.0%, 94.4%, 98.5%, 98.7%, and 97%, and one-year death-censored graft survival was 98.1%, 93.0%, 96.1%, 98.8%, and 93.0%, respectively. Cluster 2 had the worst one-year patient survival. Clusters 2 and 5 had the worst one-year death-censored graft survival. Conclusions: With the application of unsupervised machine learning, variable post-transplant outcomes are observed among morbidly obese kidney transplant recipients. Recipients with earlier access to transplant and living donation show superior outcomes. Unexpectedly, reduced graft survival in cluster 3 recipients perhaps underscores socioeconomic access to post-transplant support and minorities being disadvantaged in access to preemptive and living donor transplants. Despite obesity-related concerns, one-year patient and graft survival were favorable in all clusters, and obesity itself should be reconsidered as a hard barrier to kidney transplantation.

Kidney Transplantation in Patients After Bariatric Surgery: High-Volume Bariatric and Transplant Center Experience

BACKGROUND

Kidney transplantation (KTx) is the best type of treatment for patients with end-stage renal disease (ESRD). Unfortunately, obesity may be a contraindication for transplantation. Our study aimed to evaluate the results of KTx in patients who had bariatric surgery (BS) prior to transplantation.

METHODS

A single center, with experience in bariatric and transplant surgery, presents a retrospective study of 13 patients who received a kidney transplant after a gastric bypass (GB) operation between 2012 and 2019.

RESULTS

Thirteen patients, who were potential candidates for KTx, were previously qualified for BS because of a body mass index (BMI) > 35 kg/m². Additionally, all patients had arterial hypertension, 60% of patients had diabetes, and 30% of patients had coronary artery disease. Patients were activated on the waiting list when their BMI was < 35 kg/m². KTx was performed between 5 and 29 months after BS. One patient needed reoperation due to a urinary leak and another patient needed reoperation because of a high-pressure lymphocele. We diagnosed 2 delayed graft functions (DGFs) and 1 acute rejection. One patient died for reasons independent of surgery. The KTx observation period ranged from 3 to 8 years. Currently, 11 patients has stable renal function: creatinine concentration is 0.8-1.8 mg/dL and BMI is between 23 and 35 kg/m².

CONCLUSIONS

Despite the small group of patients, we can assume that kidney transplantation can be safely performed in patients with end-stage renal disease (ESRD) who have previously undergone gastric bypass (GB) as a graft bridging procedure. In some cases, BS may be the only chance of getting an organ.

Weight gain after renal transplant: Incidence, risk factors, and outcomes

Background

Renal transplantation is the definitive treatment for patients with end-stage renal disease (ESRD). It is associated with better quality of life and patient survival. Nevertheless, these benefits come with rising concerns about weight gain and metabolic abnormalities, which adversely impact transplant outcomes.

Objective

The objective of this study is to estimate the incidence of weight gain in the first year post-renal transplant in addition to the assessment of potential risk factors and the resulting outcome of the graft.

Methods

We conducted a single-center retrospective cohort study of all 295 patients who underwent kidney transplantation at King Abdulaziz Medical City (KAMC) between January 2016 and December 2019. Clinical and laboratory variables were collected from electronic records. Continuous variables were reported as mean ± standard deviation. Comparison between groups was assessed by unpaired t-test or Mann-Whitney U test while follow-up data were compared using paired t-test and repeated measures ANOVA. Association between the potential risk factors and the weight gain was assessed by means of binary logistic regression analysis.

Results

Significant weight gain was observed in 161 (54.6%) patients. Females were 119 (40.30%) of the cohort. The mean age was 45.3±15.1 years. The prevalence of diabetes was 234 (79.6%), while hypertensives constituted 77 (26.3%). The comparison between patients who gained weight significantly and patients with stable weight showed a numerical higher prevalence of female gender in patients who had more weight gain (44.1% vs. 35.8%), higher diabetes, higher rate of a living donor, and statistically significant lower dialysis duration before transplant. Other clinical and laboratory variables were comparable between the two groups.

Conclusion

Our study showed a high incidence of clinically significant weight gain among patients post-renal transplantation. Patients with lower dialysis duration, a living kidney donor and those who are obese at baseline were at higher risk of gaining weight. Patients who underwent kidney transplantation should be monitored closely for weight gain and further studies are needed to determine the risk factors and appropriate interventions.

Body Mass Index Thresholds and the Use of Bariatric Surgery in the Field of Kidney Transplantation in Germany

Background

Obesity in the recipient is linked to inferior transplant outcome. Consequently, access to kidney transplantation (KT) is often restricted by body mass index (BMI) thresholds. Bariatric surgery (BS) has been established as a superior treatment for obesity compared to conservative measures, but it is unclear whether it is beneficial for patients on the waiting list.

Methods

A national survey consisting of 16 questions was sent to all heads of German KT centers. Current situation of KT candidates with obesity and the status of BS were queried.

Results

Center response rate was 100%. Obesity in KT candidates was considered an important issue (96.1%; n = 49/51) and 68.6% (n = 35/51) of departments responded to use absolute BMI thresholds for KT waiting list access with ≥ 35 kg/m² (45.1%; n = 23/51) as the most common threshold. BS was considered an appropriate weight loss therapy (92.2%; n = 47/51), in particular before KT (88.2%; n = 45/51). Sleeve gastrectomy was the most favored procedure (77.1%; n = 37/51). Twenty-one (41.2%) departments responded to evaluate KT candidates with obesity by default but only 11 (21.6%) had experience with ≥ n = 5 transplants after BS. Concerns against BS were malabsorption of immunosuppressive therapy (39.2%; n = 20/51), perioperative morbidity (17.6%; n = 9/51), and malnutrition (13.7%; n = 7/51).

Conclusions

Obesity is potentially limiting access for KT. Despite commonly used BMI limits, only few German centers consider BS for obesity treatment in KT candidates by default. A national multicenter study is desired by nearly all heads of German transplant centers to prospectively assess the potentials, risks, and safety of BS in KT waitlisted patients.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s11695-022-06000-4.

Robotic Kidney Transplant: The Modern Era Technical Revolution

Since the mid 20th century, transplantation has been a fast-developing field of contemporary medicine. The technical aspects of transplant operations were developed in the 1950s, with little significant change for >50 y. Those techniques allowed completion of various organ transplants and successful patient outcomes, but they also carried the inherent disadvantages of open surgery, such as postoperative pain, wound complications and infections, and prolonged length of hospital stay. The introduction and adoption of minimally invasive surgical techniques in the early 1990s to various surgical specialties including general, gynecologic, and urologic surgery led to significant improvements in postoperative patient care and outcomes. Organ transplantation, with its precision demanding vascular anastomoses, initially had been considered infeasible to accomplish with conventional laparoscopic devices. The institution of robotic surgical technology in the late 1990s and its subsequent wide utilization in fields of surgery changed its accessibility and acceptance. With the steady camera, 3D views, and multidirectional wrist motions, surgical robotics opened new horizons for technically demanding surgeries such as transplantation to be completed in a minimally invasive fashion. Furthermore, the hope was this technique could find a niche to treat patients who otherwise are not deemed surgical candidates in many fields including transplantation. Here in, robotics in kidney transplantation and its ability to help provide equity through access to transplantation will be discussed.

Mammalian Target of Rapamycin Inhibitors and Wound Healing Complications in Kidney Transplantation: Old Myths and New Realities

Mammalian target of rapamycin inhibitors (mTOR-I) lacks nephrotoxicity, has antineoplastic effects, and reduces viral infections in kidney transplant recipients. Earlier studies reported a significant incidence of wound healing complications and lymphocele. This resulted in the uncomfortable willingness of transplant clinicians to use these agents in the immediate posttransplant period. As evidence and experience evolved over time, much useful information became available about the optimal use of these agents. Understandably, mTOR-I effects wound healing through their antiproliferative properties. However, there are a lot of other immunological and nonimmunological factors which can also contribute to wound healing complications. These risk factors include obesity, uremia, increasing age, diabetes, smoking, alcoholism, and protein-energy malnutrition. Except for age, the rest of all these risk factors are modifiable. At the same time, mycophenolic acid derivatives, steroids, and antithymocyte globulin (ATG) have also been implicated in wound healing complications. A lot has been learnt about the optimal dose of mTOR-I and their trough levels, its combinations with other immunosuppressive medications, and patients' profile, enabling clinicians to use these agents appropriately for maximum benefits. Recent randomized control trials have further increased the confidence of clinicians to use these agents in immediate posttransplant periods.

Robot-assisted kidney transplantation: an update

Renal transplantation has become the gold-standard treatment for the majority of patients with established renal failure. Recent decades have seen significant progress in immunosuppressive therapies and advances in post-transplant management of recipients, resulting in improved graft and patient outcomes. However, the open technique of allograft implantation has stood the test of time, remaining largely unchanged. In a world where major advances in surgery have been facilitated by innovations in the fields of biotechnology and medical instrumentation, minimally invasive options have been introduced for the recipient undergoing kidney transplantation. In this review we present the evolution of minimally invasive kidney transplantation, with a specific focus on robot-assisted kidney transplant and the benefits it offers to specific patient groups. We also discuss the ethical concerns that must be addressed by transplant teams considering developing or referring to robotic programs.

Dialysis of the Obese Patient: Meeting Needs for a Growing Epidemic

Increasing population obesity and associated metabolic consequences has led to increased number of obese patients with chronic kidney disease and end-stage renal disease. While obesity is associated with increased cardiovascular morbidity and mortality, obese dialysis patients present a seeming paradox for survival benefit, given other acute intervening illnesses for those on dialysis with loss of lean body mass overtime. Challenges remain in providing adequate renal replacement options and therapy for this growing segment of obese patients on dialysis which are discussed in this article.

Obesity and bariatric surgery in kidney transplantation: A clinical review

Obesity is increasing worldwide, and this has major implications in the setting of kidney transplantation. Patients with obesity may have limited access to transplantation and increased posttransplant morbidity and mortality. Most transplant centers incorporate interventions aiming to target obesity in kidney transplant candidates, including dietary education and lifestyle modifications. For those failing nutritional restriction and medical therapy, the use of bariatric surgery may increase the transplant candidacy of patients with obesity and end-stage renal disease (ESRD) and may potentially improve the immediate and late outcomes. Bariatric surgery in ESRD patients is associated with weight loss ranging from 29.8% to 72.8% excess weight loss, with reported mortality and morbidity rates of 2% and 7%, respectively. The most commonly performed bariatric surgical procedures in patients with ESRD and in transplant patients are laparoscopic sleeve gastrectomy (LSG) and laparoscopic Roux-en-Y gastric bypass. However, the correct timing of bariatric surgery and the ideal type of surgery have yet to be determined, although pretransplant LSG seems to be associated with an acceptable risk-benefit profile. We review the impact of obesity on kidney transplant candidates and recipients and in potential living kidney donors, exploring the potential impact of bariatric surgery in addressing obesity in these populations, thereby potentially improving posttransplant outcomes.

A Roadmap for Innovation to Advance Transplant Access and Outcomes: A Position Statement From the National Kidney Foundation

Over the past 65 years, kidney transplantation has evolved into the optimal treatment for patients with kidney failure, dramatically reducing suffering through improved survival and quality of life. However, access to transplant is still limited by organ supply, opportunities for transplant are inequitably distributed, and lifelong transplant survival remains elusive. To address these persistent needs, the National Kidney Foundation convened an expert panel to define an agenda for future research. The key priorities identified by the panel center on the needs to develop and evaluate strategies to expand living donation, improve waitlist management and transplant readiness, maximize use of available deceased donor organs, and extend allograft longevity. Strategies targeting the critical goal of decreasing organ discard that warrant research investment include educating patients and clinicians about potential benefits of accepting nonstandard organs, use of novel organ assessment technologies and real-time decision support, and approaches to preserve and resuscitate allografts before implantation. The development of personalized strategies to reduce the burden of lifelong immunosuppression and support "one transplant for life" was also identified as a vital priority. The panel noted the specific goal of improving transplant access and graft survival for children with kidney failure. This ambitious agenda will focus research investment to promote greater equity and efficiency in access to transplantation, and help sustain long-term benefits of the gift of life for more patients in need.

Abdominal Panniculectomy Can Simplify Kidney Transplantation in Obese Patients

BACKGROUND

Obesity is frequently present in patients suffering from end-stage renal disease (ESRD). However, overweight kidney transplant candidates are a challenge for the transplant surgeon. Obese patients tend to develop a large abdominal panniculus after weight loss creating an area predisposed to wound-healing disorders. Due to concerns about graft survival and postoperative complications after kidney transplantation, obese patients are often refused in this selective patient cohort. The study aimed to analyze the effect of panniculectomies on postoperative complications and transplant candidacy in an interdisciplinary setting.

METHODS

A retrospective database review of 10 cases of abdominal panniculectomies performed in patients with ESRD prior to kidney transplantation was conducted.

RESULTS

The median body mass index was 35.2 kg/m2 (range 28.5-53.0 kg/m2) at first transplant-assessment versus 31.0 kg/m2 (range 28.0-34.4 kg/m2) at panniculectomy, and 31.6 kg/m2 (range 30.3-32.4 kg/m2) at kidney transplantation. We observed no major postoperative complications following panniculectomy and minor wound-healing complications in 2 patients. All aside from 1 patient became active transplant candidates 6 weeks after panniculectomy. No posttransplant wound complications occurred in the transplanted patients.

CONCLUSION

Abdominal panniculectomy is feasible in patients suffering ESRD with no major postoperative complications, thus converting previously ineligible patients into kidney transplant candidates. An interdisciplinary approach is advisable in this selective patient cohort.

Obesity and Post-Transplant Diabetes Mellitus in Kidney Transplantation

Worldwide, the prevalence obesity, diabetes, and chronic kidney disease is increasing apace. The relationship between obesity and chronic kidney disease is multidimensional, especially when diabetes is also considered. The optimal treatment of patients with chronic kidney disease includes the need to consider weight loss as part of the treatment. The exact relationship between obesity and kidney function before and after transplantation is not as clear as previously imagined. Historically, patients with obesity had worse outcomes following kidney transplantation and weight loss before surgery was encouraged. However, recent studies have found less of a correlation between obesity and transplant outcomes. Transplantation itself is also a risk factor for developing diabetes, a condition known as post-transplant diabetes mellitus, and is related to the use of immunosuppressive medications and weight gain following transplantation. Newer classes of anti-diabetic medications, namely SGLT-2 inhibitors and GLP-1 agonists, are increasingly being recognized, not only for their ability to control diabetes, but also for their cardio and renoprotective effects. This article reviews the current state of knowledge on the management of obesity and post-transplant diabetes mellitus for kidney transplant patients.

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.

A Nephrologist Perspective on Obesity: From Kidney Injury to Clinical Management

Obesity is one of the epidemics of our era. Its prevalence is higher than 30% in the U.S. and it is estimated to increase by 50% in 2030. Obesity is associated with a higher risk of all-cause mortality and it is known to be a cause of chronic kidney disease (CKD). Typically, obesity-related glomerulopathy (ORG) is ascribed to renal hemodynamic changes that lead to hyperfiltration, albuminuria and, finally, impairment in glomerular filtration rate due to glomerulosclerosis. Though not only hemodynamics are responsible for ORG: adipokines could cause local effects on mesangial and tubular cells and podocytes promoting maladaptive responses to hyperfiltration. Furthermore, hypertension and type 2 diabetes mellitus, two conditions generally associated with obesity, are both amplifiers of obesity injury in the renal parenchyma, as well as complications of overweight. As in the native kidney, obesity is also related to worse outcomes in kidney transplantation. Despite its impact in CKD and cardiovascular morbility and mortality, therapeutic strategies to fight against obesity-related CKD were limited for decades to renin-angiotensin blockade and bariatric surgery for patients who accomplished very restrictive criteria. Last years, different drugs have been approved or are under study for the treatment of obesity. Glucagon-like peptide-1 receptor agonists are promising in obesity-related CKD since they have shown benefits in terms of losing weight in obese patients, as well as preventing the onset of macroalbuminuria and slowing the decline of eGFR in type 2 diabetes. These new families of glucose-lowering drugs are a new frontier to be crossed by nephrologists to stop obesity-related CKD progression.

Simultaneous robotic kidney transplantation and bariatric surgery for morbidly obese patients with end-stage renal failure

Patients with obesity have limited access to kidney transplantation, mainly due to an increased incidence of surgical complications, which could be reduced with selective use of robotic-assisted surgery. This prospective randomized controlled trial compares the safety and efficacy of combining robotic sleeve gastrectomy and robotic-assisted kidney transplant to robotic kidney transplant alone in candidates with class II or III obesity. Twenty candidates were recruited, 11 were randomized to the robotic sleeve gastrectomy and robotic-assisted kidney transplant group and 9 to the robotic kidney transplant group. At 12-month follow-up, change in body mass index was -8.76 ± 1.82 in the robotic sleeve gastrectomy and robotic-assisted kidney transplant group compared to 1.70 ± 2.30 in the robotic kidney transplant group (P = .0041). Estimated glomerular filtration rate, serum creatinine, readmission rates, and graft failure rates up to 12 months were not different between the two groups. Length of surgery was longer in the robotic sleeve gastrectomy and robotic-assisted kidney transplant group (405 minutes vs. 269 minutes, p = .00304) without increase in estimated blood loss (120 ml vs. 117 ml, p = .908) or incidence of surgical complications. Combined robotic-assisted kidney transplant and sleeve gastrectomy is safe and effective compared to robotic-assisted kidney transplant alone.

Renal transplantation outcomes in obese patients: a French cohort-based study

Background

Whilst there are a number of publications comparing the relationship between body mass index (BMI) of kidney transplant recipients and graft/patient survival, no study has assessed this for a French patient cohort.

Methods

In this study, cause-specific Cox models were used to study patient and graft survival and several other time-to-event measures. Logistic regressions were performed to study surgical complications at 30 days post-transplantation as well as delayed graft function.

Results

Among the 4691 included patients, 747 patients were considered obese with a BMI level greater than 30 kg/m². We observed a higher mortality for obese recipients (HR = 1.37, p = 0.0086) and higher risks of serious bacterial infections (HR = 1.24, p = 0.0006) and cardiac complications (HR = 1.45, p < 0.0001). We observed a trend towards death censored graft survival (HR = 1.22, p = 0.0666) and no significant increased risk of early surgical complications.

Conclusions

We showed that obesity increased the risk of death and serious bacterial infections and cardiac complications in obese French kidney transplant recipients. Further epidemiologic studies aiming to compare obese recipients versus obese candidates remaining on dialysis are needed to improve the guidelines for obese patient transplant allocation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12882-021-02278-1.

Obesity, Chronic Kidney Disease, and Kidney Transplantation: An Evolving Relationship

Obesity has a fundamental role in driving the global kidney disease burden. The perplexing relationship of obesity with chronic kidney disease remains debated. However, a thorough understanding of the interplay of obesity in conjunction with chronic kidney disease and appropriate management options is lacking, leading to further increases in morbidity and mortality. Moreover, underutilization of bariatric procedures and unrealistic expectations of weight reduction based on body mass index, leading to poor access to kidney transplantation, are fueling the fire. In this review, we summarize the available data related to the obesity and chronic kidney disease association and its novel management options.

Implications for body weight extremes in solid organ transplantation

The pharmacokinetic profiles of medications are altered in overweight and underweight patients, but few studies have described these differences in patients with body mass index extremes. As solid organ transplant programs expand their candidate selection criteria to accommodate a growing population of patients with weight extremes, it has become imperative to understand and evaluate the impact weight extremes have on the pharmacokinetics of life-sustaining immunosuppression in this population. This review will describe pharmacokinetic and dosing considerations for weight extremes in solid organ transplant recipients, including changes following bariatric surgeries, non-pharmacologic and pharmacologic management strategies for weight loss and gain, and potential drug-drug interactions with popular weight management products.

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.

Novel approaches to sarcopenic obesity and weight management before and after kidney transplantation

PURPOSE OF REVIEW

Although a widely recognized and complex pathophysiological condition, sarcopenic obesity remains less appreciated and may elude diagnosis and workup in both kidney transplant waitlisted candidates and kidney transplant recipients. The lack of consensus definition, and practical diagnostic tools for evaluating waitlisted candidates and transplant recipients are barriers to early detect and initiate therapeutic management for sarcopenic obesity. Although sarcopenia leads to poor clinical outcomes, posttransplant obesity yields conflicting results. Exercise and nutritional managements are common therapies for sarcopenic obese patients; however, surgery weight loss or bariatric surgery in both transplant candidates and potential living kidney donors shows promising benefits for kidney transplant access in waitlist obese candidates but may require to be selected for appropriate patients.

RECENT FINDINGS

Pathogenesis and management for sarcopenia and obesity are interconnected. The benefits of exercise to improve muscle mass and function is clear in waitlist kidney transplant candidates and transplant recipients. However, there are several barriers for those to increase exercise and improve physical activity including patient, provider, and healthcare or environmental factors. The advantages of fat mass reduction to lose weight can promote muscle mass and strength. However, epidemiological data regarding the obesity paradox in dialysis-dependent patients when overnutrition provides survival benefits for this population should be taken into account when performing weight loss especially bariatric surgery.

SUMMARY

Barriers in providing optimal care to kidney transplant waitlisted candidates and transplant recipients may partly result from underdiagnosis of sarcopenic obesity; notwithstanding that this entity has increasingly been more recognized. Mechanistic studies to better understand pathogenesis of sarcopenic obesity will help determine pathogenesis and clinical tools for diagnosis of this entity, which can facilitate further studies related to the outcomes and weight management to ultimately improve kidney transplant outcomes.

Long-Term Outcomes and Prognostic Factors in Kidney Transplant Recipients with Polycystic Kidney Disease

Background

Polycystic kidney disease (PKD) accounts for approximately 15% of kidney transplants, but long-term outcomes in patients with PKD who have received a kidney transplant are not well understood.

Methods

In primary recipients of kidney transplants at our center (1994-2014), we compared outcomes of underlying PKD (N=619) with other native diseases (non-PKD, N=4312). Potential factors influencing outcomes in PKD were evaluated using Cox proportional-hazards regression and a rigorous multivariable model.

Results

Patients with PKD were older and were less likely to be sensitized or to experience delayed graft function (DGF). Over a median follow-up of 5.6 years, 1256 of all recipients experienced death-censored graft failure (DCGF; 115 patients with PKD) and 1617 died (154 patients with PKD). After adjustment for demographic, dialysis, comorbid disease, surgical, and immunologic variables, patients with PKD had a lower risk of DCGF (adjusted hazard ratio [aHR], 0.73; 95% CI, 0.57 to 0.93; P=0.01) and death (aHR, 0.62; 95% CI, 0.51 to 0.75; P<0.001). In our multiadjusted model, calcineurin-inhibitor (CNI) use was associated with lower risk of DCGF (aHR, 0.45; 95% CI, 0.26 to 0.76; P=0.003), whereas HLA mismatch of five to six antigens (aHR, 2.1; 95% CI, 1.2 to 3.64; P=0.009) was associated with higher likelihood of DCGF. Notably, both pretransplant coronary artery disease (CAD) and higher BMI were associated with increased risk of death (CAD, aHR, 2.5; 95% CI, 1.69 to 3.71; P<0.001; per 1 kg/m² higher BMI, aHR, 1.07; 95% CI, 1.04 to 1.11; P<0.001), DCGF, and acute rejection. Nephrectomy at time of transplant and polycystic liver disease were not associated with DCGF/death. Incidence of post-transplant diabetes mellitus was similar between PKD and non-PKD cohorts.

Conclusions

Recipients with PKD have better long-term graft and patient survival than those with non-PKD. Standard practices of CNI use and promoting HLA match are beneficial in PKD and should continue to be promoted. Further prospective studies investigating the potential benefits of CNI use and medical/surgical interventions to address CAD and the immunologic challenges of obesity are needed.

Podcast

This article contains a podcast at https://dts.podtrac.com/redirect.mp3/www.asn-online.org/media/podcast/K360/2021_02_25_KID0001182019.mp3.

Surgical complications risk in obese and overweight recipients for kidney transplantation: a predictive morphometric model based on sarcopenia and vessel-to-skin distance

PURPOSE

Sarcopenia or adipose tissue distribution within obese and overweight renal transplanted have been poorly evaluated. Our objective was to evaluate morphometric markers to predict surgical complications in kidney transplantation.

METHODS

We retrospectively included patients with a BMI > 25 kg/m² undergoing kidney transplantation from 2012 to 2017. Following measurements were performed on CT-scan sections: Sub-cutaneous Adipose Tissue surface (SAT), Visceral Adipose Tissue surface (VAT), Vessel-to-Skin distance (VSK), Abdominal Perimeter (AP), and Psoas surface. A multivariable logistic regression model with BMI was compared to a model containing morphometric variables to determine the best predictive model for surgical complications.

RESULTS

248 patients were included, 15 (6%) experienced transplant nephrectomy, 18 (7.3%) urinary leakage, and 29 (11.7%) subcapsular renal hematoma. Multivariable logistic regression evidenced that sarcopenia and VSK were risk factors of surgical complication within a year post-transplantation (respectively, OR = 0.9, 95%CI (0.8-0.9), p = 0.04 and OR = 1.2, 95%CI (1.1-1.3), p = 0.002). Area under the curve for a predictive model including VSK, age and psoas surface was 0.69, whereas BMI model was 0.65.

CONCLUSION

Combined morphometric parameters of obesity were associated with surgical complications in kidney transplantation. Morphometric threshold may provide a more accurate and objective criteria than BMI to evaluate kidney transplantation outcomes. External validation is needed.

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.

Laparoscopic sleeve gastrectomy for morbid obesity in renal transplantation candidates: a matched case-control study

Obesity has become an important issue in patients with end-stage renal disease (ESRD). Since it is considered a relative contraindication for renal transplantation, bariatric surgery has been advocated to treat morbid obesity in transplant candidates, and laparoscopic sleeve gastrectomy (LSG) is the most reported procedure. However, comparative data regarding outcomes of LSG in patients with or without ESRD are scarce. Consecutive patients with ESRD (n = 29) undergoing LSG were compared with matched patients with normal renal function undergoing LSG in a 1:3 ratio using propensity score adjustment. Data were collected from a prospective database. Eligibility for transplantation was also studied. A lower weight loss (20 kg (16-30)) was observed in patients with ESRD within the first year as compared to matched patients (28 kg (21-34)) (P < 0.05). After a median follow-up of 30 (19-50) months in the ESRD group, contraindication due to morbid obesity was lifted in 20 patients. Twelve patients underwent transplantation. In patients with ESRD potentially eligible for transplantation, LSG allows similar weight loss in comparison with matched patients with normal renal function, enabling lifting contraindication for transplantation due to morbid obesity in the majority of patients within the first postoperative year.

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.

Sleeve Gastrectomy Compared with Gastric Bypass for Morbidly Obese Patients with End Stage Renal Disease: a Decision Analysis

INTRODUCTION

The use of bariatric surgery has increased for morbidly obese patients with end stage renal disease (ESRD) for whom listing on the waitlist is often restricted until a certain BMI threshold is achieved. Effective weight loss for this population improves access to life-saving renal transplantation. However, it is unclear whether sleeve gastrectomy (SG) vs Roux-en-Y gastric bypass (RYGB) is a more effective therapy for these patients.

METHODS

A decision analytic Markov state transition model was created to simulate the life of morbidly obese patients with ESRD who were deemed ineligible to be waitlisted for renal transplantation unless they achieved a BMI less than 35 kg/m². Life expectancy following weight management (MWM), RYGB, and SG were estimated. Base case patients were defined as having a pre-intervention BMI of 45 kg/m². Sensitivity analysis of initial BMI was performed. Markov parameters were extracted from literature review.

RESULTS

RYGB improved survival compared with SG and MWM. RYGB patients had higher rates of transplantation, leading to improved mean long-term survival. Base case patients who underwent RYGB gained 1.3 additional years of life compared with patient's who underwent SG and 2.6 additional years of life compared with MWM.

CONCLUSIONS

RYGB improves access to renal transplantation and thereby increases long-term survival compared with SG and MWM. The use of SG may be incongruent with the goal of improving access to renal transplantation for morbidly obese patients.

Temporary contraindication of obese recipients in kidney transplantation: A new morphometric tool for decision support

BACKGROUND

Morbid obesity, based on body mass index (BMI) and/or clinical examination, can be a temporary contraindication (TCI) of kidney transplantation. However, BMI alone does not evaluate the intra- or extra-peritoneal distribution of fatty tissue, and clinical examination alone is subjective. The objective was to evaluate the interest of morphometric criteria to ensure reproducible and consensual decision of TCI.

METHODS

We retrospectively included patients with a BMI >30 transplanted or temporarily contraindicated because of their weight from 2012 to 2017. The following measurements were performed on CT scan sections using a semiautomatic Hounsfield density detection software: subcutaneous adipose tissue surface (SAT), visceral adipose tissue surface (VAT), vessel-to-skin distance (VSK), abdominal perimeter (AP), and psoas index. Performance of morphometric measures to predict TCI was assessed through ROC analysis.

RESULTS

Ninety-seven patients were included: 76 kidney transplant recipients and 21 on the TCI list. The area under the curve (AUC, 95%CI) for the BMI model to predict TCI was 0.81 (0.72-0.90). A 5-variable model including BMI, VAT, VSK, AP, and age gave an AUC of 0.88 (0.78-0.98).

CONCLUSIONS

Morphometric obesity parameters are associated with TCI decision-making for kidney transplantation: When combined with BMI in a "morphometric tool," they were predictive of a TCI decision.

Cardiovascular disease in the kidney transplant recipient: epidemiology, diagnosis and management strategies

Kidney transplantation (KT) is the optimal therapy for end-stage kidney disease (ESKD), resulting in significant improvement in survival as well as quality of life when compared with maintenance dialysis. The burden of cardiovascular disease (CVD) in ESKD is reduced after KT; however, it still remains the leading cause of premature patient and allograft loss, as well as a source of significant morbidity and healthcare costs. All major phenotypes of CVD including coronary artery disease, heart failure, valvular heart disease, arrhythmias and pulmonary hypertension are represented in the KT recipient population. Pre-existing risk factors for CVD in the KT recipient are amplified by superimposed cardio-metabolic derangements after transplantation such as the metabolic effects of immunosuppressive regimens, obesity, posttransplant diabetes, hypertension, dyslipidemia and allograft dysfunction. This review summarizes the major risk factors for CVD in KT recipients and describes the individual phenotypes of overt CVD in this population. It highlights gaps in the existing literature to emphasize the need for future studies in those areas and optimize cardiovascular outcomes after KT. Finally, it outlines the need for a joint 'cardio-nephrology' clinical care model to ensure continuity, multidisciplinary collaboration and implementation of best clinical practices toward reducing CVD after KT.

Gene co-expression networks are associated with obesity-related traits in kidney transplant recipients

Background

Obesity is common among kidney transplant recipients; However biological mediators of obesity are not well understood in this population. Because subcutaneous adipose tissue can be easily obtained during kidney transplant surgery, it provides a unique avenue for studying the mechanisms of obesity for this group. Although differential gene expression patterns were previously profiled for kidney transplant patients, gene co-expression patterns can shed light on gene modules not yet explored on the coordinative behaviors of gene transcription in biological and disease processes from a systems perspective.

Methods

In this study, we collected 29 demographic and clinical variables and matching microarray expression data for 26 kidney transplant patients. We conducted Weighted Gene Correlation Network Analysis (WGCNA) for 5758 genes with the highest average expression levels and related gene co-expression to clinical traits.

Results

A total of 35 co-expression modules were detected, two of which showed associations with obesity-related traits, mainly at baseline. Gene Ontology (GO) enrichment was found for these two clinical trait-associated modules. One module consisting of 129 genes was enriched for a variety of processes, including cellular homeostasis and immune responses. The other module consisting of 36 genes was enriched for tissue development processes.

Conclusions

Our study generated gene co-expression modules associated with obesity-related traits in kidney transplant patients and provided new insights regarding the cellular biological processes underlying obesity in this population.

Approaches to Obesity Management in Dialysis Settings: Renal Dietitian Perspectives

OBJECTIVES

Over 40% of individuals in the United States with end-stage kidney disease have obesity. Little is known about renal dietitian perspectives on obesity management in the setting of dialysis dependence.

DESIGN AND METHODS

An online 21-item survey was distributed to 118 renal dietitians via individual outreach and a professional organization e-mail listserv. Four themes were explored: the burden of obesity among dialysis patients, concepts of healthy weight loss, weight loss approaches, and challenges of obesity management in dialysis settings. Respondents were asked to rank approaches and biomarkers for obesity management from 0 (least important or not used) to 100 (most important). Free text fields were provided in each category for additional comments.

RESULTS

Thirty-one renal dietitians responded to the survey (26% response rate). The majority of respondents (90%) indicated that access to kidney transplantation was the main reason that dialysis patients with obesity desired weight loss. Calorie restriction was rated as the most common weight loss approach, and dry weight as the most important weight loss biomarker. Nearly 40% of respondents do not alter their nutritional approach when dialysis patients with obesity are losing weight, and 42% of respondents do not monitor changes in waist circumference. Exercise, diet counseling, and stress management were variably prioritized as weight loss management strategies. Barriers to obesity management in dialysis settings included lack of time, lack of training in weight loss counseling, and gaps in current renal nutritional guidelines.

CONCLUSION

Despite the high prevalence of obesity among individuals with end-stage kidney disease, the results of this survey suggest that current approaches to obesity management in dialysis settings are highly variable. Many renal dietitians lack time to counsel patients on healthy weight loss strategies. Nutritional guidelines are also needed to support people with dialysis dependence and obesity who desire or require weight loss.