Kidney Transplant Outcomes in the Super Obese: A National Study From the UNOS Dataset

Efficacy of surgical techniques for morbid obesity and their potentials in end-stage renal disease in preparation for kidney transplantation

Obesity is a modern «epidemic» not only in the general population but also among patients with end-stage renal disease (ESRD) who require kidney transplantation (KTx). The objective of this literature review is to analyze global studies on surgical methods of treating morbid obesity and their potentials in ESRD patients in preparation for KTx.

Management of obesity in kidney transplant candidates and recipients: A clinical practice guideline by the DESCARTES Working Group of ERA

The clinical practice guideline Management of Obesity in Kidney Transplant Candidates and Recipients was developed to guide decision-making in caring for people with end-stage kidney disease (ESKD) living with obesity. The document considers the challenges in defining obesity, weighs interventions for treating obesity in kidney transplant candidates as well as recipients and reflects on the impact of obesity on the likelihood of wait-listing as well as its effect on transplant outcomes. It was designed to inform management decisions related to this topic and provide the backdrop for shared decision-making. This guideline was developed by the European Renal Association's Developing Education Science and Care for Renal Transplantation in European States working group. The group was supplemented with selected methodologists to supervise the project and provide methodological expertise in guideline development throughout the process. The guideline targets any healthcare professional treating or caring for people with ESKD being considered for kidney transplantation or having received a donor kidney. This includes nephrologists, transplant physicians, transplant surgeons, general practitioners, dialysis and transplant nurses. Development of this guideline followed an explicit process of evidence review. Treatment approaches and guideline recommendations are based on systematic reviews of relevant studies and appraisal of the quality of the evidence and the strength of recommendations followed the Grading of Recommendations Assessment, Development and Evaluation approach. Limitations of the evidence are discussed and areas of future research are presented.

Early Postoperative Outcomes of Super Morbid Obese Compared to Morbid Obese Patients After Ambulatory Surgery Under General Anesthesia: A Propensity-Matched Analysis of a National Database

BACKGROUND

Patients with body mass index (BMI) ≥50 kg/m2, defined as super morbid obesity, represent the fastest growing segment of patients with obesity in the United States. It is currently unknown if super morbid obese patients are at greater odds than morbid obese patients for poor outcomes after outpatient surgery. The main objective of the current investigation is to assess if super morbid obese patients are at increased odds for postoperative complications after outpatient surgery when compared to morbid obese patients.

METHODS

The American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database from 2017 to 2018 was queried to extract and compare patients who underwent outpatient surgery and were defined as either morbidly obese (BMI >40 and <50 kg/m2) or super morbidly obese (BMI ≥50 kg/m2). The primary outcome was the occurrence of medical adverse events within 72 hours of discharge. In addition, we also examine death and readmissions as secondary outcomes. A propensity-matched analysis was used to evaluate the association of BMI ≥50 kg/m2 versus BMI between 40 and 50 kg/m2 and the outcomes.

RESULTS

A total of 661,729 outpatient surgeries were included in the 2017-2018 NSQIP database. Of those, 7160 with a BMI ≥50 kg/m2 were successfully matched to 7160 with a BMI <50 and ≥40 kg/m2. After matching, 17 of 7160 (0.24%) super morbid obese patients had 3-day medical complications compared to 15 of 7160 (0.21%) morbid obese patients (odds ratio [OR; 95% confidence interval {CI}] = 1.13 [0.57-2.27], P = .72). The rate of 3-day surgical complications in super morbid obese patients was also not different from morbid obese patients. Thirty-five of 7160 (0.48%) super morbid obese patients were readmitted within 3 days, compared to 33 of 7160 (0.46%) morbid obese patients (OR [95% CI] = 1.06 [0.66-1.71], P = .80). When evaluated in a multivariable analysis as a continuous variable (1 unit increase in BMI) in all patients, BMI ≥40 kg/m2 was not significantly associated with overall medical complications (OR [95% CI] = 1.00 [0.98-1.04], P = .87), overall surgical complication (OR [95% CI] = 1.02 [0.98-1.06], P = .23), or readmissions (OR [95% CI] = 0.99 [0.97-1.02], P = .8).

CONCLUSIONS

Super morbid obesity is not associated with higher rates of early postoperative complications when compared to morbid obese patients. Specifically, early pulmonary complications were very low after outpatient surgery. Super morbid obese patients should not be excluded from outpatient procedures based on a BMI cutoff alone.

Nonlinear relationship between body mass index and clinical outcomes after kidney transplantation: A dose-response meta-analysis of 50 observational studies

BACKGROUND

Exact dose-response relationship between body mass index at transplantation and clinical outcomes after kidney transplantation remained unclear, and no specific body mass index threshold and pretransplant weight loss aim were recommended for kidney transplantation candidates among transplant centers.

METHODS

PubMed, Embase, Web of Science, and Cochrane Library were searched for literature published up to December 31, 2019. The two-stage, random effect meta-analysis was performed to estimate the dose-response relationship between body mass index and clinical outcomes after kidney transplantation.

RESULTS

Ninety-four studies were included for qualitative assessment and 50 for dose-response meta-analyses. There was a U-shaped relationship between graft loss, patient death, and body mass index. Body mass index with the lowest risk of graft loss was 25.2 kg/m², and preferred body mass index range was 22-28 kg/m². Referring to a body mass index of 22 kg/m², the risk of graft loss was 1.088, 0.981, 1.003, and 1.685 for a body mass index of 18, 24, 28, and 40 kg/m², respectively. Body mass index with the lowest risk of patient death was 24.7 kg/m², and preferred body mass index range was 22-27 kg/m². Referring to a body mass index of 22 kg/m², the patient death risk was 1.115, 0.981, 1.032, and 2.634 for a body mass index of 18, 24, 28, and 40 kg/m², respectively. J-shaped relationships were observed between body mass index and acute rejection, delayed graft function, primary graft nonfunction, and de novo diabetes. Pair-wise comparisons showed that higher body mass index was also a risk factor for cardiovascular diseases, hypertension, infection, longer length of hospital stay, and lower estimated glomerular filtration rate level.

CONCLUSION

Underweight and severe obesity at transplantation are associated with a significantly increased risk of graft loss and patient death. A target body mass index at kidney transplantation is 22-27 kg/m².

But Why Weight: Understanding the Implications of Obesity in Kidney Transplant

Obesity is increasing in prevalence among candidates for kidney transplant. Understanding the influence of obesity on candidate evaluation, surgical risk, peritransplant management, and post-transplant outcomes is critical to ensuring equitable access to transplant for this growing population.

The Effects of Sex and Body Weight on Renal Graft Function-The Role of CCL2

There are reports on the effects of excessive recipient body weight on renal graft function. Increased CCL2 (chemokine CC-mortif ligand 2) production is observed in patients with excessive body weight. CCL2 also exacerbates the inflammatory process in the renal graft. A total of 49 renal graft recipients of both sexes having undergone renal biopsy within the last 18 months were retrospectively reviewed. At their most recent appointment the patients’ plasma concentrations of CCL2 were evaluated. Renal function was assessed retrospectively. CCL2 concentrations were higher in men than women (p < 0.047), while higher CCL2 levels were associated with a decrease in eGFR (estimated glomerular filtration rate) during the first year post Tx (kidney transplantation). CCL2 negatively correlated with eGFR at 5 years (R = −0.45, p < 0.040997) and positively correlated with the degree of tubular atrophy in renal biopsy specimens (R = 0.43, p < 0.027293) and with systolic pressure. Men showed significantly higher BMI (body mass index) values at the time of Tx and at their last appointment than women did (p < 0.000403; p < 0.000613, respectively). Men showed poorer long-term renal graft function, with significantly lower eGFR values at 4 and 5 years into the post-transplantation period. The male sex and excessive body weight have adverse effects on short- and long-term renal graft function, which is associated with increased levels of CCL2.

Management of Obesity in Adults with CKD

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

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

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.

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

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

One-Year Outcomes of a Cohort of Renal Transplant Patients Related to BMI in a Steroid-Sparing Regimen

BACKGROUND

The prevalence of overweight and obese kidney transplant recipients (KTR) has risen in parallel to the obesity epidemic that has affected the general population over the last two decades. At present, there is an ongoing debate regarding the suitability for transplantation of obese patients.

METHODS

Data were prospectively collected on consecutive single organ KTR transplanted between January 2014 and March 2016. The patients were stratified according to their body mass index (BMI) using the World Health Organization classification. As a measure of allograft function Modification of Diet in Renal Disease, estimated glomerular filtration rate was used at 3, 6, and 12 months posttransplant.

RESULTS

We included 370 KTR: 126 of 370 women; median age, 52.7 years (range, 19-77 years), followed up for a median of 19.5 ± 8.6 months. In total, 155 (41.9%) KTR were underweight or of normal BMI at transplant, whereas 148 (40%) were overweight, and 67 (18.1%) were classified as obese (47 [12.7%] class 1, 11 [3%] class 2, 9 [2.4%] class 3). Overweight and obese KTR had a higher incidence of pretransplant diabetes (P = 0.021), but no difference was found in new-onset hyperglycemia posttransplant (P = 0.35). There was also no difference in posttransplant hospital length of stay (P = 0.386). Obese and overweight KTR had a significantly lower estimated glomerular filtration rate than underweight and normal BMI KTR at 3 and 6 months posttransplant, a finding that did not persist at 1 year follow-up. Overall, 23 patients lost their grafts, and 20 patients died during follow-up. Kaplan Meier analysis showed no difference in allograft loss between the different BMI groups (log rank P = 0.7).

CONCLUSIONS

In this single-center study, which used short-term data, overweight and obese patients were shown not to have inferior outcomes regarding renal function 1 year posttransplant.

Impact of super obesity on perioperative outcomes after hepatectomy: The weight of the risk

BACKGROUND

We evaluated perioperative outcomes in super obese patients (body mass index >50 kg/m²) undergoing liver resection using the American College of Surgeons National Surgical Quality Improvement Program.

METHODS

Patients undergoing hepatectomy recorded in the American College of Surgeons National Surgical Quality Improvement Program dataset from 2005 to 2015 were analyzed. Out of 21,228 hepatectomies in the National Surgical Quality Improvement Program dataset, 146 were performed on super obese patients.

RESULTS

Seventy-two percent of the super obese patients were female with a median age of 50.6 years, and 10% were classified as American College of Surgeons Class ≥III. In this group, 69.2% were hypertensive, 38.4% were diabetics, and 17.8% had dyspnea. The median operation time was 248 minutes in the super obese group, greater than any other body mass index class. Twenty-two percent of these patients required perioperative transfusion, although 74% underwent partial hepatectomies. Body mass index >50 kg/m² significantly increased morbidity in patients undergoing hepatectomies, almost 2-fold. Infectious complications increased by 86%, and the risk of developing critical care complications increased by 63%.

CONCLUSION

Our data show that super obesity (body mass index >50 kg/m²) is the strongest independent predictor of perioperative morbidity. These patients also are at much greater risk of infectious complications and critical care complications. Future studies should be conducted using weight loss strategies in extreme obese patients to reduce their risk of life-threatening complications after hepatectomy.

Body Size and Outcomes in Dialysis and Transplant Patients - Does it Matter?

The terminologies of "body size", "body mass index (BMI)", "body weight", "large BMI" and "obesity" are controversial for defining the effects of "adiposity" or "fat excess" on the outcomes of dialysis and transplant patients. However, probably these terminologies will be continued to be used in the future as well, because of being older and simpler terminologies. In the general population obesity is a powerful risk factor for cardiovascular morbidity and mortality, while, it conferred a survival advantage to dialysis patients. However, this may be a oversimplification, since obesity may still be a risk factor in non-sarcopenic hemodialysis patients. Obesity is associated with early post-transplant adverse effects (i.e. delayed graft function, graft failure, wound infections, also transplant costs) and unfavorable graft and patient survival. However, thanks to safer immunosuppressive protocols, recently graft and patient survival is similar in obese as those of the non-obese patients. On the other hand, morbid obesity may still be a cause of unfavorable patient and graft survival. Since obese transplant recipients have better life expectancy as compared to wait-listed hemodialysis patients, they should be transplanted as well, while morbidly obese patients should be asked to lose weight before being placed in the waiting lists.