Challenges of Abdominal Organ Transplant in Obesity:

Evaluating the safety of bariatric surgery as a bridge to kidney transplant: a retrospective cohort study

BACKGROUND

Bariatric surgery has been proven safe in end-stage kidney disease (ESKD); however, few studies have evaluated whether a history of bariatric surgery impacts transplant-specific outcomes. We hypothesize that a history of bariatric surgery at the time of transplant does not adversely impact transplant-specific outcomes.

METHODS

The IBM MarketScan Commercial Claims and Encounters database was queried for patients with a history of kidney transplant between 2000 and 2021. Patients were stratified into three groups based on bariatric surgery status and body mass index (BMI) at the time of transplant: patients with obesity (O), patients without obesity (NO), and patients with a history of bariatric surgery (BS). Inverse probability of treatment weighting was used to control for confounding. Adjusted hazard ratios (aHRs) describing the risk of transplant-specific and postoperative outcomes were estimated using weighted Kaplan-Meier curves. Primary outcomes included 30-day and 1-year risk of transplant-specific outcomes. Secondary outcomes included 30-day and 1-year postoperative complications and 30-day and 1-year risk of wound-related complications.

RESULTS

We identified 14,806 patients; 128 in the BS group, 1572 in the O group, and 13,106 in the NO group. There was no difference in 30-day or 1-year risk of transplant-specific complications between the BS and NO group or the O and NO group. Patients with obesity (O) were more likely to experience wound infection (aHR 1.49, 95% CI 1.12-1.99), wound dehiscence (aHR 2.2, 95% CI 1.5-3.2), and minor reoperation (aHR 1.52, 95% CI 1.23-1.89) at 1 year. BS patients had increased risk of wound infection at 1 year (aHR 2.79, 95% CI 1.26-6.16), but were without increase in risk of minor or major reoperation.

CONCLUSION

A history of bariatric surgery does not adversely affect transplant-specific outcomes after kidney transplant. Bariatric surgery can be safely utilized to improve the transplant candidacy of patients with obesity with CKD and ESKD.

Low-Volume Home Haemodialysis and In-Centre Haemodialysis: Comparison of Dialysis Adequacy in Obese Individuals

Background Although frequent low-flow, low-volume haemodialysis using the NxStage System One is now well-established as an option for home therapy of end-stage chronic kidney disease, its ability to deliver adequate dialysis in people with high BMI remains questionable. This doubt may lead to obese individuals being denied the potential benefits of this modality. To establish if this doubt is justified, we compared dialysis adequacy in two groups of obese individuals; one receiving standard thrice-weekly in-centre haemodialysis and the other receiving frequent haemodialysis at home using the NxStage System One. Methods This is a retrospective observational cohort study of 105 adult dialysis patients with obesity (BMI ≥ 30 kg/m2). All had been on dialysis for at least six months. Fifty-five patients receiving in-centre haemodialysis were compared with 50 patients receiving home haemodialysis using NxStage System One. Dialysis adequacy (standard Kt/V calculated by the Daugirdas equation) was compared between the two groups. The clinical characteristics, laboratory test results, and treatment regimens of each group were also compared. Results The in-centre haemodialysis group was older (63.6 ± 12.8 years vs. 58.5 ± 10.9 years, p=0.033) and had a higher Charlson comorbidity score (5.9 ± 2.1 vs. 4.5 ± 2.5, p=0.003). Standard Kt/V was significantly higher in the home haemodialysis group (2.4 ± 0.5) than in the in-centre haemodialysis group (2.2 ± 0.2) (p = 0.006). The mean serum inorganic phosphate was significantly lower in the home haemodialysis group than in the in-centre haemodialysis group (1.6 ± 0.4 mmol/l vs. 1.8 ± 0.5 mmol/l, p = 0.010). There were no statistically significant differences in the usage of antihypertensives, phosphate binders, or erythropoiesis-stimulating agents between the two groups. Conclusions In this study, dialysis adequacy (expressed as standard Kt/V) was superior to that of standard thrice-weekly in-center haemodialysis delivered by frequent low-volume home haemodialysis using the NxStage System One. Hesitancy about recommending frequent low-volume home haemodialysis to obese individuals is therefore unjustified.

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

Background:

Obesity is associated with increased surgical complications and long-term cardiovascular mortality. Studies of access in kidney transplantation have found a bias against obese patients on the wait-listing.

Objective:

To determine the current state of clinical practice for the management of obesity in kidney transplantation.

Design:

A survey in two versions, PDF and traditional paper, composed of categorical questions.

Setting:

A pan-Canadian survey of transplant nephrologists and surgeons.

Methods:

The survey PDF was distributed electronically to the Kidney Group of the Canadian Society of Transplantation. A shorter, hardcopy version was distributed subsequently at a national transplant meeting.

Results:

There were 47 responses, including almost every Canadian adult transplant program. Most (81%) reported the use of a body mass index limit for access to the waiting list. However, only 40% reported a strict enforcement. There were several instances of intra-hospital disagreements regarding the use of a policy, among the centers with multiple responses. The body mass index limit was most commonly 40 kg/m² (62%), followed by 35 kg/m² (36%). Despite the body mass index limit, few centers (30%) reported having a weight management program. The reported experience with bariatric surgery was small, though nearly all replied that they would refer to a bariatric specialist in the future.

Limitations:

This national survey provides a broad assessment of clinical practice. The distinction between an official policy and informal clinical tendencies is difficult. The results cannot be used to support any specific limit or policy.

Conclusions:

This survey found that the body mass index limit for access to the kidney transplant waiting list was common in Canada. Several inconsistencies suggest a lack of official policy. To achieve equity in access, clear guidelines for obesity should be established and enforced. Bariatric surgery has the promise of rapid weight loss. Resource allocation to study obesity in transplant patients will be essential.

Obesity and metabolic syndrome in kidney transplantation

The epidemic of obesity and metabolic syndrome (MS) contributes to the rapid growth of chronic kidney disease (CKD) and end-stage renal disease (ESRD). There is a reverse epidemiology, known as the "obesity paradox," in ESRD patients receiving maintenance dialysis. Obese patients are routinely referred for kidney transplant, and they have more surgical and medical complications than non-obese patients. However, compared to dialysis, kidney transplant provides a survival benefit for obese patients. After kidney transplant, obese patients tend to gain more body weight, and non-obese patients can develop new-onset obesity/MS. Obesity/MS is not only associated with serious morbidities, but also compromises the long-term graft and patient survival. The immunosuppressive drugs commonly used as maintenance therapy, including corticosteroids, calcineurin inhibitors and mammalian target-of-rapamycin inhibitors, contribute to obesity/MS. Development of novel immunosuppressive drugs free of metabolic adverse effects is needed, so that the full potential and benefits of kidney transplantation can be realized.

Expanding the donor pool in pancreas transplantation

PURPOSE OF REVIEW

The current era of organ shortage has necessitated expansion of the currently available organ donor pool, to increase the number of pancreases available for transplant. This review summarizes the cumulative efforts of various centers in making this possible.

RECENT FINDINGS

Various centers are consistently reporting their experience with marginal donors; recent additions to the cohort have been increase in pancreases from donors after cardiac death (controlled and uncontrolled), update on long-term outcomes of live pancreas donors, as well as efforts at objectively assessing donor risk.

SUMMARY

It has become important for the transplanting surgeon to make difficult decisions on organ suitability and appropriateness depending upon the recipient's status. Further more, limiting further damage to these vulnerable grafts is important in improving utilization as well as successful transplantation.

The impact of recipient obesity on outcomes after renal transplantation

BACKGROUND

The benefit of renal transplantation in obese patients is controversial, with many centers setting upper limits on body mass index (BMI) in consideration for listing patients for transplant. This study was undertaken to determine the effect of recipient obesity on delayed graft function (DGF) and graft survival after renal transplantation.

METHODS

Retrospective review of all renal transplant recipients in the United Network for Organ Sharing database from January 1, 2004, through December 31, 2009, was performed. Primary endpoints were DGF and non-death-censored graft survival. Comparisons were made on the basis of the following weight classes: nonobese (BMI < 30), class I obese (30 ≤ BMI < 35), class II obese (35 ≤ BMI < 40), and class III obese (BMI ≥ 40).

RESULTS

Multivariable logistic regression indicated a significantly increased risk for DGF in obese patients. The odds ratios for DGF compared with nonobese patients were 1.34 [95% confidence interval (CI) 1.27-1.42; P < 0.001], 1.68 (95% CI 1.56-1.82; P < 0.001), and 2.68 (95% CI 2.34-3.07; P < 0.001) for the class I obese, class II obese, and class III obese groups, respectively. Class I obesity was not a significant risk for non-death-censored graft failure [hazard ratio (HR) 1.00, 95% CI 0.95-1.05; P = 0.901] compared with nonobese patients. Patients in the class II obese (HR 1.15, 95% CI 1.07-1.24; P < 0.001) and class III obese (HR 1.26, 95% CI 1.11-1.43; P < 0.001) groups were at a significantly increased risk for graft failure than their nonobese counterparts.

CONCLUSIONS

Obese patients in all weight classes are at an increased risk for DGF after renal transplantation, although differences in non-death-censored graft survival are such that transplantation should not be denied on the basis of BMI criteria alone.

Increased morbidity in overweight and obese liver transplant recipients: a single-center experience of 1325 patients from the United Kingdom

Obesity levels in the United Kingdom have risen over the years. Studies from the United States and elsewhere have reported variable outcomes for obese liver transplant recipients in terms of post-liver transplant morbidity, mortality, and graft survival. This study was designed to analyze the impact of the body mass index (BMI) on outcomes following adult liver transplantation. Data from 1994 to 2009 were retrieved from a prospectively maintained database. Patients were stratified into 5 World Health Organization BMI categories: underweight (<18.5 kg/m(2)), normal weight (18.5-24.9 kg/m(2)), overweight (25.0-29.9 kg/m(2)), obese (30.0-34.9 kg/m(2)), and morbidly obese (≥35.0 kg/m(2)). The primary outcome was an evaluation of graft and patient survival, and the secondary outcome was an assessment of postoperative morbidity. Bonferroni correction was applied with statistical significance set at P < 0.012. Kaplan-Meier curves were used to study the effects of BMI on graft and patient survival. A total of 1325 patients were included in the study: underweight (n = 47 or 3.5%), normal-weight (n = 643 or 48.5%), overweight (n = 417 or 31.5%), obese (n = 145 or 10.9%), and morbidly obese patients (n = 73 or 5.5%). The rate of postoperative infective complications was significantly higher in the overweight (60.7%, P < 0.01) and obese recipients (65.5%, P < 0.01) versus the normal-weight recipients (50.4%). The morbidly obese patients had a longer mean intensive care unit (ICU) stay than the normal-weight patients (4.7 versus 3.2 days, P = 0.03). The mean hospital stay was longer for the overweight (22.4 days, P < 0.001), obese (21.3 days, P = 0.04), and morbidly obese recipients (22.4 days, P = 0.047) versus the normal-weight recipients (18.0 days). There was no difference in death-censored graft survival or patient survival between the groups. In conclusion, this is the largest and only reported UK series on BMI and outcomes following liver transplantation. Overweight and obese patients have significantly increased morbidity in terms of infective complications after liver transplantation and, consequently, longer ICU and hospital stays.

Does morbid obesity change outcomes after laparoscopic surgery for inflammatory bowel disease? Review of 626 consecutive cases

BACKGROUND

Little is known about the impact of obesity on morbidity in patients with inflammatory bowel disease (IBD) who are undergoing laparoscopic resections. The aim of this study was to evaluate outcomes in a consecutive series of normal weight (NW), overweight (OW), and obese (OB) patients undergoing elective laparoscopic colorectal surgery for IBD.

STUDY DESIGN

This study is a retrospective analysis of a prospectively collected, Institutional Review Board-approved IBD database.

RESULTS

Laparoscopic colorectal resection was performed in 626 patients (335 NW, 206 OW, and 85 OB) between August 2002 and December 2011. Operative time and blood loss were significantly higher in the OW and OB groups compared with the NW group (p = 0.001 and p < 0.001). No differences were observed in terms of intraoperative blood transfusions (p = 0.738) or complications (p = 0.196). The OW and OB groups had a significantly higher conversion rate (p = 0.049 and p = 0.037) and a longer incision compared with the NW group (p = 0.002 and p < 0.001). Obesity was an independent predictor of conversion to open surgery. No significant differences between groups were observed in terms of overall 30-day postoperative morbidity (p = 0.294) and mortality (p = 0.796). Long-term complications occurred in 6.3% NW, 7.3% OW, and 4.7% OB patients (p = 0.676). Incisional hernias were more common in the OB group compared with the NW group (p = 0.020). On multivariate analysis, obesity was not an independent risk factor for either early or late postoperative complications.

CONCLUSIONS

Obesity increases the complexity of laparoscopic resections in IBD with higher blood loss, operative time, and conversion rates, without worsening outcomes.

Home hemodialysis: a successful option for obese and bariatric people with end-stage kidney disease

The increasing prevalence of obesity in developed countries is reflected in the chronic kidney disease, dialysis, and transplant populations. The added risk factor of obesity increases the risk of vascular events, inflammation, insulin resistance, blood pressure, dyslipidemia, and mortality risk. Nephrology center policies may exclude obese people from transplantation programs resulting in many years of dialysis. The case of a 215-kg Australian male who has successfully dialyzed at home for more than 8 years will be used to illustrate the important considerations and clinical support that these people require for successful home dialysis treatment. The aim of this paper is to report on a program that has successfully trained 23 obese (body mass index >30) people who commenced on home hemodialysis between 2001 and 2009. Body weight ranged between 94.0 and 215 kg (mean 126, SD 26.19) and body mass index ranged between 34.9 and 71 (mean 43.38, SD 9.99) at the start of home training. During the 8.5 years of follow-up, average time on home dialysis was 43.7 months. Home hemodialysis is a feasible treatment for obese people to facilitate longer and more frequent dialysis, resulting in improved hemodynamic stability and improved quality of life. For obese people with end-stage kidney disease, home hemodialysis has shown to be cost-effective and can result in greater treatment efficacy than in-center hospital dialysis.

The impact of obesity on outcomes following major surgery for Crohn's disease: an American College of Surgeons National Surgical Quality Improvement Program assessment

BACKGROUND

Whereas Crohn's disease is traditionally thought to represent a wasting disease, little is currently known about the incidence and impact of obesity in this patient cohort.

OBJECTIVE

This study aimed to evaluate the perioperative outcomes in patients with Crohn's disease who were obese vs those who were not obese undergoing major abdominal surgery.

DESIGN

This study is a retrospective review of the American College of Surgeons National Surgical Quality Improvement Program database (2005-2008). Risk-adjusted 30-day outcomes were assessed by the use of regression modeling accounting for patient characteristics, comorbidities, and surgical procedures.

PATIENTS

Included were all patients with Crohn's disease who were undergoing abdominal operations.

MAIN OUTCOME MEASURE

The primary outcomes measured were short-term perioperative outcomes. Obesity was defined as a BMI of 30 or greater.

RESULTS

We identified 2319 patients (mean age, 41.6 y; 55% female). Of these patients, 379 (16%) met obesity criteria, 2% were morbidly obese, and 0.3% were super obese. Rates of obesity significantly increased each year over the study period. Twenty-five percent of the surgeries were performed laparoscopically (obese 21% vs nonobese 26%). Six percent were emergent, with no difference in patients with obesity. Operative times were significantly longer among patients with obesity (177 min) compared with patients who were not obese (164 min). After adjusting for differences in comorbidities and steroid use, overall perioperative morbidity was significantly higher in the obese cohort (32% vs 22% nonobese; OR 1.9). In addition, the rates of postoperative complications increased directly with rising BMI. Irrespective of procedure type, the patients who were obese were significantly more likely to experience wound infections (OR 1.7), which increased even further in patients who were morbidly obese (BMI >40; OR 7.1). By specific operation, postoperative morbidity was increased in patients with obesity following colectomies with primary anastomosis for both open and laparoscopic approaches (OR 2.9 and OR 3.8). Cardiac, pulmonary, and renal complications as well as overall mortality did not differ significantly based on BMI.

LIMITATIONS

This study was limited by being a retrospective review, and by using data limited to the American College of Surgeons National Surgical Quality Improvement Program database.

CONCLUSION

Increasing BMI adversely affects perioperative morbidity in patients with Crohn's disease.

Pancreas transplantation after bariatric surgery

Obese transplant candidates are at increased risk for perioperative and postoperative complications. In many transplant programs, morbid obesity is considered to be an exclusion criterion for transplantation. The only potential option that would grant these patients access to transplant is weight loss. Non-operative weight loss strategies such as behavioral modifications, exercise, diet, or medication have only very limited success in achieving long-term weight loss. In contrast, bariatric surgery was shown to achieve not only more excessive weight loss, but more importantly, this weight loss can be sustained for longer periods of time. Therefore, bariatric surgery presents an attractive option for weight loss for morbidly obese transplant candidates. We report our experience with four patients who underwent bariatric surgery prior to successful pancreas transplantation. Even though gastric bypass and laparoscopic adjustable gastric band present as equivalent alternatives for weight reduction, we believe that in the population of morbidly obese diabetic patients who are possible candidates for pancreas transplantation, laparoscopic adjustable gastric band placement is the more suitable procedure.

New-onset diabetes after renal transplantation: diagnosis, incidence, risk factors, impact on outcomes, and novel implications

OBJECTIVE

New-onset diabetes after transplantation (NODAT) is a multifactorial, complex metabolic disorder associated with impaired long-term graft function, reduced recipient survival, and increased risks of cardiovascular disease and infectious complications. The impact of NODAT is generally underestimated partly due to the inconsistent criteria that have been previously used for its diagnosis and to the generally short observation periods. The aim of this article was to review the recent literature on NODAT and to highlight the novel implications.

FINDINGS

The 2010 American Diabetes Association guidelines provide useful, simplified criteria to unify the diagnosis including application of hemoglobin A1C levels. We sought to establish the impact of various modifiable and nonmodifiable risk factors. A vast number of papers have examined the effects of immunosuppressive medications on the development of NODAT: Neither calcineurin inhibitor nor sirolimus (SRL) or steroids seems to be innocent of contributing to it. Immunosuppressants account for 74% of the occurrence of NODAT. Among modifiable risk factors, obesity is independent and significant, with great prevalence in the population. In additional to lifestyle modifications, the role of bariatric surgery (BS) either before or after transplantation is highlighted herein as a strategy to reduce disease in the view of the results among overweight, nontransplanted patients.

SUMMARY

Because of the strong association between high glucose values in the early posttransplant period and the development of NODAT, the condition must be recognized early after (or even before) transplantation by intensive screening. Patients at risk for NODAT must modify appropriate risk factors and particularly undergo pretransplant planning and/or posttransplant adjustment individualizing immunosuppressive therapy to mitigate the risk of this serious complication.