Survey of Canadian Kidney Transplant Specialists on the Management of Morbid Obesity and the Transplant Waiting List

Economic evaluation of weight loss and transplantation strategies for kidney transplant candidates with obesity

Novel antiobesity medications, particularly glucagon-like peptide-1 receptor agonists (GLP-1RAs), have expanded weight loss (WL) options for kidney transplantation (KT) candidates with obesity beyond lifestyle modifications and bariatric surgery. However, varying effectiveness, risk profiles, and costs make strategy choices challenging. To aid decision-making, we used a Markov model to examine the cost-effectiveness of different WL strategies over a 10-year horizon. A target WL of 15% of total body weight was used for the base case scenario, and we compared these strategies to a "liberal" KT strategy of transplanting candidates with obesity. Outcomes included costs (2023 US dollars), quality-adjusted life years, and incremental cost-effectiveness ratios. In analysis, a liberal KT strategy was favored over lifestyle modifications and GLP-1RAs. Among WL strategies, bariatric surgery was the most effective and cost the least, whereas lifestyle modification had the highest cumulative costs and was the least effective. Compared to liberal KT, bariatric surgery costs $45 859 per quality-adjusted life year gained. GLP-1RAs were favored over bariatric surgery only when drug costs were below $5000 per year (base cost $12 077). In conclusion, for KT candidates with obesity, a liberal KT strategy and bariatric surgery are preferred over lifestyle modifications alone and GLP-1RAs based on outcomes and cost-effectiveness.

The Impact and Effectiveness of Weight Loss on Kidney Transplant Outcomes: A Narrative Review

Obesity is a worldwide epidemic that leads to several non-communicable illnesses, including chronic kidney disease (CKD). Diet and lifestyle modifications have shown a limited impact in the treatment of obesity. Because the group of end-stage renal disease (ESRD) patients examined in this study had limited access to kidney transplantation (KT), patients with obesity were thought to be at an increased risk of intraoperative and postoperative KT complications. Although bariatric surgery (BS) is now recognized as the gold standard treatment for morbid obesity, its role in ESRD or kidney transplant patients remains unknown. It is critical to know the correlation between weight loss and complications before and after KT, the impact of the overall graft, and patients' survival. Hence, this narrative review aims to present updated reports addressing when to perform surgery (before or after a KT), which surgical procedure to perform, and again, if strategies to avoid weight regain must be specific for these patients. It also analyzes the metabolic alterations produced by BS and studies its cost-effectiveness pre- and post-transplantation. Due to the better outcomes found in KT recipients, the authors consider it more convenient to perform BS before KT. However, more multicenter trials are required to provide a solid foundation for these recommendations in ERSD patients with obesity.

An ethical analysis of obesity as a contraindication of pediatric kidney transplant candidacy

The inclusion of body mass index (BMI) as a criterion for determining kidney transplant candidacy in children raises clinical and ethical challenges. Childhood obesity is on the rise and common among children with kidney failure. In addition, obesity is reported as an independent risk factor for the development of CKD and kidney failure. Resultantly, more children with obesity are anticipated to need kidney transplants. Most transplant centers around the world use high BMI as a relative or absolute contraindication for kidney transplant. However, use of obesity as a relative or absolute contraindication for pediatric kidney transplant is controversial. Empirical data demonstrating poorer outcomes following kidney transplant in obese pediatric patients are limited. In addition, pediatric obesity is distributed inequitably among groups. Unlike adults, most children lack independent agency to choose their food sources and exercise opportunities; they are dependent on their families for these choices. In this paper, we define childhood obesity and review (1) the association and impact of obesity on kidney disease and kidney transplant, (2) existing adult guidelines and rationale for using high BMI as a criterion for kidney transplant, (3) the prevalence of childhood obesity among children with kidney failure, and (4) the existing literature on obesity and pediatric kidney transplant outcomes. We then discuss ethical considerations related to the use of obesity as a criterion for kidney transplant.

Outcomes of kidney transplant recipients who underwent pre-transplant bariatric surgery for severe obesity: a long-term follow-up study

BACKGROUND

Kidney transplantation (KT) is the preferred therapy for end-stage renal disease (ESRD). While a major cause for ESRD, obesity is also a key obstacle to candidacy for KT. Bariatric surgery, particularly sleeve gastrectomy (SG), is increasingly used to improve access to KT in patients with obesity, but the literature especially on outcomes post-KT remains lacking. We aimed to provide a long-term follow-up analysis of efficacy and outcomes of a previously described cohort of patients with obesity, who had SG as a means for access to KT.

METHODS

This is a single-center retrospective follow-up study of 32 patients with advanced chronic kidney disease or ESRD, who were referred and underwent SG between 2013 and 2018 as an access strategy to KT. The primary outcome was successful KT. Ninety-day outcomes, long-term graft function, and changes in weight and obesity-related comorbidities after KT were assessed. Descriptive statistics are presented as count (percentage) or median (interquartile range).

RESULTS

At baseline, 18 (56%) were male with a median age and BMI of 51 (11) years and 42.3 (5.2) kg/m², respectively. Median follow-up time post-SG was 53 (58) months. At last follow-up, 23 (72%) patients received KT. Median time to KT was 16 (20) months and BMI was 34.0 (5.1) kg/m² at time of transplant. At KT, 13 (57%) and 20 (87%) had diabetes and hypertension, respectively. Median follow-up post-KT was 16 (47) months. There was one graft loss requiring return to dialysis. At 5-year post-KT, median serum creatinine was 136 (66) µmol/l. At last follow-up post-KT, median BMI remained at 33.7 (7.6) kg/m². Among patients with diabetes and hypertension, 7/13 (54%) and 5/20 (25%) had either improvement or remission of their comorbidities, respectively.

CONCLUSION

SG is an effective strategy to improve access to KT in patients with severe obesity. Transplant recipients also continue to benefit from sustained weight loss and improved related comorbidities that may positively impact their graft function after KT.

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.

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.

Conservative Management of Obesity in Kidney Transplant Candidates

OBJECTIVE

Obesity is prevalent in patients with chronic kidney disease and is associated with increased complications after kidney transplantation (KT). A body mass index limit is used in most transplant programs, though few studies have focused on conservative weight loss in KT candidates. The objective of this retrospective study is to evaluate the efficacy of a basic conservative weight management program in morbidly obese KT candidates and to perform a comprehensive nutritional evaluation.

METHODS

This retrospective study included patients with a body mass index (BMI) >35 kg/m^2, with grade IV or V chronic kidney disease. The conservative weight loss program consisted of anthropometric measurements every 3 months, consultation with a nutritionist, daily exercise, and counseling for healthier eating habits. Overall and quarterly BMI targets were defined. A subset of patients further underwent a comprehensive nutritional evaluation to measure socioeconomic characteristics, food intake behavior, motivation for change, and a 4-day food diary.

RESULTS

Eighty patients were observed for a mean of 24 months. Successful weight loss (BMI < 35 kg/m²) was achieved in 26.3%, associated with women and those already close to the limit. The mean 1-year excess body weight loss was 8.4%. No patient with a BMI >40 kg/m² was successful. The comprehensive nutritional evaluation was performed with 44 patients and found that only 14.6% had previously received nutritional counseling for weight loss. Cognitive restraint scored highest in the food-intake behavior. Most patients were motivated to lose weight with 66% in the action phase. There was little evidence of overeating with a recommended mean calculated daily caloric intake of 82.9%.

CONCLUSION

The conservative weight loss program can have limited but non-negligible, success. Future successful nutritional interventions should take into consideration this surprising comprehensive profile of morbidly obese KT candidates.

Usability and experience testing to refine an online intervention to prevent weight gain in new kidney transplant recipients

OBJECTIVES

Weight gain in the first year following kidney transplantation increases the risk of adverse health outcomes. Currently, there is no recognized intervention available to prevent weight gain after kidney transplantation. An online kidney transplant-specific resource, entitled Exercise in Renal Transplant Online (ExeRTiOn), has been co-created by a multi-professional team, including patients, to assist with weight prevention. This study aimed to evaluate patient and health care professional usability and experience of the ExeRTiOn online resource.

DESIGN

Qualitative study utilizing 'Think-Aloud' and semi-structured interviews.

METHODS

Participants (n = 17) were purposively sampled to include new kidney transplant recipients (n = 11) and transplant health care professionals (n = 6). Kidney transplant recipient participants were from a spread of physical activity levels based on scores from the General Practice Physical Activity Questionnaire (GPPAQ). 'Think-Aloud' interviews assessed the usability of ExeRTiOn. Semi-structured interviews explored participants' experience of ExeRTiOn, weight gain, and physical activity. The data set were analysed thematically. Participant characteristics, including login data and self-reported body weight, were collected.

RESULTS

Data analyses identified valued intervention content and usability aspects which were summarized by two themes. The first theme 'You need to know how to manage yourself' included subthemes: (1) the resource filled a guidance gap, (2) expert patient content resonated, and (3) the importance of goal setting and monitoring progress. The second theme 'room for improvement' included subthemes: (2) web support and (2) content and operational change suggestions.

CONCLUSIONS

Results have allowed for identification of potential areas for resource refinement. This has facilitated iterative enhancement of ExeRTiOn in preparation for a randomized controlled feasibility trial.

Bariatric surgery to achieve transplant in end-stage organ disease patients: A systematic review and meta-analysis

BACKGROUND

As obesity prevalence grows, more end-stage organ disease patients will be precluded from transplant. Numerous reports suggest bariatric surgery in end-stage organ disease may help patients achieve weight loss sufficient for transplant listing.

METHODS

We performed a systematic review/meta-analysis of studies of bariatric surgery to achieve solid organ transplant listing.

RESULTS

Among 82 heart failure patients, 40.2% lost sufficient weight for listing, 29.3% were transplanted, and 8.5% had sufficient improvement with weight loss they no longer required transplantation. Among 28 end-stage lung disease patients, 28.6% lost sufficient weight for listing, 7.1% were transplanted, and 14.3% had sufficient improvement following weight loss they no longer required transplant. Among 41 cirrhosis patients, 58.5% lost sufficient weight for listing, 41.5% were transplanted, and 21.9% had sufficient improvement following weight loss they no longer required transplant. Among 288 end-stage/chronic kidney disease patients, 50.3% lost sufficient weight for listing and 29.5% were transplanted.

CONCLUSIONS

Small sample size and publication bias are limitations; however, bariatric surgery may benefit select end-stage organ disease patients with obesity that precludes transplant candidacy.

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.

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.

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.

Variation in Practice Patterns for Listing Patients for Renal Transplantation in the United Kingdom: A National Survey

BACKGROUND

Despite the availability of guidelines for the evaluation of candidates for renal transplantation, variation in access to transplantation exists. This national survey investigates whether center variation exists in the assessment of patients for renal transplantation in the United Kingdom.

METHODS

An online survey, informed by qualitative interviews, was distributed to all UK renal centers. This survey examined center approaches to chronic kidney disease service provision, transplant recipient assessment, education provision, and waitlisting decision making processes. Center reevaluation policies for patients already listed and priorities for future development were also examined.

RESULTS

All 71 renal centers responded. Of these, 83% reviewed predialysis patients in a low clearance clinic. In 26% of the centers, transplantation was not discussed as a treatment option with all patients. Fourteen centers reported having a dedicated transplant assessment clinic, whereas 28% did not have a formal assessment protocol. Age was an exclusion criterion for listing in 3 centers, all of which had a cutoff at 75 years. Eighty-three percent of the centers excluded patients with a high body mass index. Cardiac investigations were risk-stratified in 90% of centers. Surgical involvement varied with 11% of centers listing patients without formal surgical review. There was no formal protocol in place to reevaluate listed patients in 62% of centers.

CONCLUSIONS

There is wide variation in UK practice patterns for listing patients for renal transplantation, though its impact on access to transplantation is unclear. The extent to which center-specific and patient-specific factors affect access to transplantation requires further analysis in a prospective cohort of patients.

Influence of the recipient body mass index on the outcomes after kidney transplantation

PURPOSE

The relationship between the body mass index (BMI) of kidney transplant recipients and outcomes after kidney transplantation (KT) is not fully understood and remains controversial. We studied the influence of BMI on clinically relevant outcomes in kidney transplant recipients.

METHODS

In this retrospective single-centre study, all patients who underwent kidney transplantation at our institution between January 2007 and December 2012 were included. Demographic data and BMI were correlated with the clinical course of the disease, rejection rates, delayed graft function rates, and graft and patient survival.

RESULTS

During the study period, 384 single KTs (130 women and 254 men) were performed. Seventeen percent of the transplants were transplanted within the Eurotransplant Senior Programme (ESP). Most of the transplants were performed using organs that were obtained from donors after brain death (DBD), and living donor kidney transplants were performed in 22.4% of all transplants. The median BMI of the recipients was 25.9 kg/m². Additionally, 13.5% of the recipients had a BMI of 30-34.9 kg/m² and 3.9% had a BMI >35 kg/m². A BMI >30 kg/m² was significantly associated with primary non-function of the kidney (p = 0.047), delayed graft function (p = 0.008), and a higher rate of loss of graft function (p = 0.015). The glomerular filtration rate 12 months after KT was significantly lower in recipients with a BMI >30 kg/m². Multivariate analysis revealed that recipient BMI, among other factors, was an independent risk factor for delayed graft function and graft survival. Patients with a BMI >30 kg/m² had an almost four times higher risk for surgical site infection than did recipients with a lower BMI.

CONCLUSIONS

Increased BMI at kidney transplantation is a predictor of adverse outcomes, including delayed graft function. These findings demonstrate the importance of the careful selection of patients and pre-transplant weight reduction, although the role of weight reduction for improving graft function is not clear.