Obesity and outcome following renal transplantation

Obesity is associated with a higher incidence of rejection in patients on belatacept: A pooled analysis from the BENEFIT/BENEFIT-EXT clinical trials

Though belatacept is administered with a weight-based dosing schema, there has been higher clearance reported in obese patients. Therefore, we evaluated the association between body mass index (BMI) and transplant outcomes in kidney transplant recipients who were randomized to cyclosporine- or belatacept-based immunosuppression in the BENEFIT and BENEFIT-EXT randomized clinical trials. A total of 666 and 543 patients underwent randomization and transplantation in BENEFIT and BENEFIT-EXT, respectively, of which 1056 had complete data and were included in this analysis. Patients were grouped categorically according to BMI: <25, 25 to <30, and ≥30 kg/m2. BMI did influence both the incidence and severity of acute rejection. Obese patients with BMI >30 kg/m2 in the low intensity belatacept group experienced significantly more rejection at 12 months than did patients with BMI <25 kg/m2 or BMI 25 to <30 kg/m2. In both the moderate intensity belatacept and low intensity belatacept groups, obese patients with BMI >30 kg/m2 experienced significantly more severe acute rejection than did patients with BMI < 25 kg/m2 or BMI 25 to <30 kg/m2. These results suggest that obese kidney transplant recipients are at an increased risk for acute rejection when under belatacept-based immunosuppression when compared to nonobese patients.

Does obesity really affect renal transplantation outcomes?

INTRODUCTION

Kidney transplantation is the treatment of choice for patients with stage 5 chronic kidney disease (CKD). About 60% of CKD patients are overweight or obese at the time of kidney transplantation, and post-transplant obesity occurs in 50% of patients, with a weight gain of 10% in the first year and high risk of cardiovascular mortality. Obesity is associated with an increased risk of delayed graft function (DGF), acute rejection, surgical complications, graft loss and mortality. The aim of this study is to assess the clinical evolution of obese and overweight patients that have received a kidney transplant, based on short- and long-term complications associated with a higher BMI.

MATERIAL AND METHODS

A descriptive, observational, cross-sectional study was conducted with 104 kidney or pancreas-kidney transplant patients between March 2017 and December 2020, with a follow-up until April 2021. For comparative analysis, patients were grouped according to BMI.

RESULTS

Mean age was of 56.65 years, 60.6% male and 39.4 % female. Overweight patients experienced prolonged surgeries, more surgical wound dehiscence, delayed graft function, hernias, proteinuria and more indications for renal biopsies. Additionally, obese patients displayed more DGF, indications for renal biopsies, proteinuria, development of diabetes mellitus, atrial fibrillation and needed prolonged hospital stays.

CONCLUSIONS

Despite a high prevalence of comorbidity in the overweight and/or obese population, we found no reduction in patient and/or graft survival. However, longer follow-up is needed.

Impact of Obesity on Kidney Transplant Outcomes in Older Adults

BACKGROUND

The prevalence of obesity in older patients undergoing kidney transplantation is increasing. Older age and obesity are associated with higher risks of complications and mortality post-transplantation. The optimal management of this group of patients remains undefined.

METHODS

We retrospectively analyzed the United Network for Organ Sharing database of adults ≥70 years of age undergoing primary kidney transplant from January 1, 2014, to December 31, 2022. We examined patient and graft survival stratified by body mass index (BMI) in 3 categories, <30 kg/m2, 30 to 35 kg/m2, and >35 kg/m2. We also analyzed other risk factors that impacted survival.

RESULTS

A total of 14,786 patients ≥70 years underwent kidney transplantation. Of those, 9,731 patients had a BMI <30 kg/m2, 3,726 patients with a BMI of 30 to 35 kg/m2, and 1,036 patients with a BMI >35 kg/m2. During the study period, there was a significant increase in kidney transplants in patients ≥70 years old across all BMI groups. Overall, patient survival, death-censored graft survival, and all-cause graft survival were lower in obese patients compared with nonobese patients. Multivariable analysis showed worse patient survival and graft survival in patients with a BMI of 30 to 35 kg/m2, a BMI >35 kg/m2, a longer duration of dialysis, diabetes mellitus, and poor functional status.

CONCLUSION

Adults ≥70 years should be considered for kidney transplantation. Obesity with a BMI of 30 to 35 kg/m2 or >35 kg/m2, longer duration of dialysis, diabetes, and functional status are associated with worse outcomes. Optimization of these risk factors is essential when considering these patients for transplantation.

Surgical complications and graft survival in kidney transplant recipients according to CT-scans evaluation

INTRODUCTION

Obesity is a risk factor for significant surgical complications following kidney transplantation. We examined morphometric parameters other than the body mass index (BMI) that could predict surgical complications and determine their impact on graft survival.

MATERIALS

Kidney transplantations performed at our center between 2012 and 2019 were retrospectively evaluated. Data for visceral adipose tissue (VAT), subcutaneous adipose tissue, psoas surface, abdominal perimeter (AP), and vessel-to-skin distance (VSK) were collected from pre-transplant computed tomography (CT) scans. The primary outcome was the occurrence of surgical complications within 1 year of transplantation; the secondary outcome was graft survival.

RESULTS

We included 321 (88%) of 364 kidney transplant recipients, of which 154 (46.5%) patients experienced some form of surgical complication in the 1st year of follow-up. Univariate analysis revealed that higher VAT (P=0.004), VSK (P=0.007), and AP (P=0.01) values were potential risk factors for early postoperative morbidity. However, none of these factors were significant in the multivariate analysis. Concerning the secondary outcome, while the univariate analysis identified higher VAT (P=0.001) value as a risk factor, in the multivariate analysis only delayed graft function demonstrated a significant impact on graft survival (P=0.002).

CONCLUSIONS

Although morphological parameters showed greater accuracy in predicting surgical complications in univariate analysis, these results were not significant in multivariate analysis. Moreover, these factors were not significantly associated with graft survival. Therefore, routine application of analyses based on these parameters, regardless of BMI, may not be useful.

LEVEL OF EVIDENCE: 5

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.

[Anesthesia for organ transplant patients]

Organ transplant patients who must undergo nontransplant surgical interventions can be challenging for the anesthesiologists in charge. On the one hand, it is important to carefully monitor the graft function in the perioperative period with respect to the occurrence of a possible rejection reaction. On the other hand, the ongoing immunosuppression may have to be adapted to the perioperative requirements in terms of the active substance and the route of administration, the resulting increased risk of infection and possible side effects (e.g., myelosuppression, nephrotoxicity and impairment of wound healing) must be included in the perioperative treatment concept. Furthermore, possible persistent comorbidities of the underlying disease and physiological peculiarities as a result of the organ transplantation must be taken into account. Support can be obtained from the expertise of the respective transplantation center.

Comparative outcomes of bariatric surgery in patients with ESRD on dialysis in the modern era of renal transplantation: analysis using the 2015-2020 MBSAQIP database

BACKGROUND

Severe obesity is a relative contraindication for renal transplantation, therefore bariatric surgery is an important option as a pre-kidney transplant weight loss strategy. However, comparative data regarding postoperative outcomes of laparoscopic sleeve gastrectomy (LSG) or laparoscopic Roux-en-Y gastric bypass (LRYGB) in patients with or without ESRD on dialysis are scarce.

METHODS

Patients between 18- and 80-year-old who underwent LSG and RYGB were included. To determine the outcomes of patient who underwent bariatric surgery with ESRD on dialysis, a 1:4 PSM was performed between the patients with ESRD on dialysis and those without renal disease. The PSM analyses in both groups were performed using 20 preoperative characteristics. Then 30-day postoperative outcomes were assessed.

RESULTS

The operative time and postoperative-LOS were significantly longer in ESRD patients on dialysis compared to those with no renal disease either for LSG (82.37 ± 40.42 vs. 73.62 ± 38.65; P < 0.001, 2.22 ± 3.01 vs. 1.67 ± 1.90; P < 0.001) or for LRYGB (129.13 ± 63.20 vs. 118.72 ± 54.16; P = 0.002, 2.53 ± 1.74 vs. 2.00 ± 1.68; P < 0.001). In the LSG cohort (2137 vs. 8495 matched cases), patients with ESRD on dialysis showed significant increase in mortality (0.7% vs 0.3%; P = 0.019), unplanned ICU admission (3.1% vs 1.3%; P < 0.001), blood transfusions (2.3% vs 0.8%; P 0.001), readmissions (9.1% vs. 4.0%; P < 0.001), reoperations (3.4% vs. 1.2%; P < 0.001), interventions (2.3% vs. 1.0%; P = 0.006). In the LRYGB group (443 vs. 1769 matched cases), patients with ESRD on dialysis showed a significantly higher need for unplanned ICU admission (3.8% vs. 1.4%; P = 0.027), readmissions (12.4% vs. 6.6%; P = 0.011), and interventions (5.2% vs. 2.0%; P = 0.050).

CONCLUSION

Bariatric surgery is a safe procedure for patients with ESRD on dialysis to help them get a kidney transplant. Even though this group experienced a higher incidence of postoperative complications compared to those without kidney disease, the absolute complication rates are low and not associated with bariatric-specific complications. Therefore, ESRD should not be perceived as contraindications to bariatric surgery.

Effect of Pre-Transplant Recipient Underweight on the Postoperative Outcome and Graft Survival in Primary Kidney Transplantation

BACKGROUND

The objective of this study was to evaluate the influence of recipient underweight on the short- and long-term outcomes of patients undergoing primary kidney transplantation (KT).

PATIENTS AND METHODS

Three hundred thirty-three patients receiving primary KT in our department between 1993 and 2017 were included in the study. Patients were divided according to their body mass index (BMI) into underweight (BMI <18.5 kg/m2; N = 29) and normal weight (BMI 18.5-24.9 kg/m2; N = 304) groups. Clinicopathological characteristics, postoperative outcomes, and graft and patient survival were analyzed retrospectively.

RESULTS

The postoperative rate of surgical complications and renal function were comparable between the groups. One year and 3 years after KT, 70% and 92.9%, respectively, of the pre-transplant underweight patients reached a normal BMI (≥18.5 kg/m2). The mean death-censored graft survival was significantly lower in pre-transplant underweight patients than in pre-transplant normal-weight patients (11.5 ± 1.6 years vs 16.3 ± 0.6 years, respectively; P = .045). Especially KT recipients with a moderate or severe pre-transplant underweight (BMI <17 kg/m2; N = 8) showed an increased rate of graft loss (5- and 10-year graft survival: 21.4% each). No statistical difference could be observed between the 2 groups regarding causes of graft loss. In multivariate analysis, recipient underweight (P = .024) remained an independent prognostic factor for graft survival.

CONCLUSION

Being underweight did not affect the early postoperative outcome after primary KT. However, underweight, and especially moderate and severe thinness, is associated with reduced long-term kidney graft survival, and therefore this group of patients should be monitored with special attention.

Comparable kidney transplant outcomes in selected patients with a body mass index ≥ 40: A personalized medicine approach to recipient selection

INTRODUCTION

Many kidney transplant (KT) centers decline patients with a body mass index (BMI) ≥40 kg/m2 . This study's aim was to evaluate KT outcomes according to recipient BMI.

METHODS

We performed a single-center, retrospective review of adult KTs comparing BMI ≥40 patients (n = 84, BMI = 42 ± 2 kg/m2 ) to a matched BMI < 40 cohort (n = 84, BMI = 28 ± 5 kg/m2 ). Patients were matched for age, gender, race, diabetes, and donor type.

RESULTS

BMI ≥40 patients were on dialysis longer (5.2 ± 3.2 years vs. 4.1 ± 3.5 years, p = .03) and received lower kidney donor profile index (KDPI) kidneys (40 ± 25% vs. 53 ± 26%, p = .003). There were no significant differences in prevalence of delayed graft function, reoperations, readmissions, wound complications, patient survival, or renal function at 1 year. Long-term graft survival was higher for BMI ≥40 patients, including after adjusting for KDPI (BMI ≥40: aHR = 1.79, 95% CI = 1.09-2.9). BMI ≥40 patients had similar BMI change in the first year post-transplant (delta BMI: BMI ≥ 40 +.9 ± 3.3 vs. BMI < 40 +1.1 ± 3.2, p = .59).

CONCLUSIONS

Overall outcomes after KT were comparable in BMI ≥40 patients compared to a matched cohort with lower BMI with improved long-term graft survival in obese patients. BMI-based exclusion criteria for KT should be reexamined in favor of a more individualized approach.

Obesity is Associated With Delayed Graft Function in Kidney Transplant Recipients: A Paired Kidney Analysis

Obesity is increasingly prevalent among candidates for kidney transplantation. Existing studies have shown conflicting post-transplant outcomes for obese patients which may relate to confounding bias from donor-related characteristics that were unaccounted for. We used ANZDATA Registry data to compare graft and patient survival between obese (BMI >27.5 kg/m2 Asians; >30 kg/m2 non-Asians) and non-obese kidney transplant recipients, while controlling for donor characteristics by comparing recipients of paired kidneys. We selected transplant pairs (2000-2020) where a deceased donor supplied one kidney to an obese candidate and the other to a non-obese candidate. We compared the incidence of delayed graft function (DGF), graft failure and death by multivariable models. We identified 1,522 pairs. Obesity was associated with an increased risk of DGF (aRR = 1.26, 95% CI 1.11-1.44, p < 0.001). Obese recipients were more likely to experience death-censored graft failure (aHR = 1.25, 95% CI 1.05-1.49, p = 0.012), and more likely to die with function (aHR = 1.32, 95% CI 1.15-1.56, p = 0.001), versus non-obese recipients. Long-term patient survival was significantly worse in obese patients with 10- and 15-year survival of 71% and 56% compared to 77% and 63% in non-obese patients. Addressing obesity is an unmet clinical need in kidney transplantation.

Transplanting a left or right donor kidney into the left or right iliac fossa: importance of laterality and site of venous anastomosis

Data on the impact of donor-to-recipient laterality on kidney transplantation are lacking. This study evaluated the impact of donor-to-iliac fossa laterality and the site of venous anastomosis on operating time and surgical outcome. This retrospective single-center study analyzed 1262 deceased donor adult kidney transplants into pristine iliac fossa. Multivariable linear and logistic regression analyses were used to identify variables with an impact on operating time and surgical complications. Operating time was shorter by 11 min in median for transplantations into the right iliac fossa compared to the left iliac fossa (p < 0.001). Operating time in left-to-right donor-to-recipient combination was shorter by 17 min in median if venous anastomoses were performed on the caval vein or common iliac vein as compared to anastomoses to the external iliac vein (p < 0.001). Overall, the shortest operating times (median 112.5 min) were achieved in left-to-right donor-to-recipient combinations with venous anastomosis to the caval or common iliac vein, without an increase in surgical complications. Kidney transplantation into the right iliac fossa with anastomosis to the caval vein or the common iliac vein saves operating time and reduces thrombotic complications. Acceptance of a left donor kidney is likely to further reduce operating time.

Obesity Affects Short-Term Renal Function After Renal Transplantation

BACKGROUND

The literature has shown a significant association between body mass index (BMI) and patient and graft outcomes after renal transplantation. The purpose of this study was to reveal the effect of obesity on graft function in a Taiwanese kidney transplant cohort.

METHODS

Two hundred consecutive patients who received kidney transplantation were enrolled in our study. Eight pediatric cases were excluded due to differing definitions of BMI among children. According to the national obesity criteria, these patients were divided into underweight, normal, overweight, and obese groups. Their estimated glomerular filtration rate (eGFR) was compared accordingly using t tests. Cumulative graft and patient survivals were calculated using Kaplan-Meier analysis. A P value of ≤ .05 was considered significant.

RESULTS

The mean age of our cohort (105 men and 87 women) was 45.3 years. There was no significant difference comparing biopsy-proven acute rejection, acute tubular necrosis, and delayed graft function between the obese and nonobese groups (P values: .293, .787, and .304, respectively). Short-term eGFR was inferior in the overweight group, but this effect was insignificant beyond 1 month. The 1-month and 3-month eGFR were found to be correlated with BMI groups (P = .012 and P = .008, respectively) but not significant after 6 months post-kidney transplantation.

CONCLUSIONS

Our study found that short-term renal function was affected by obesity and being overweight, possibly due to the higher prevalence of diabetes and dyslipidemia in obese patients and the increased surgical difficulty.

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.

Combined liver transplantation and sleeve gastrectomy: Report of a brief-interval staged approach

Pretransplantation bariatric surgery in patients with high Model for End-Stage Liver Disease (MELD) score is fraught with risks. Bariatric surgery after liver transplantation (LT) may be complicated by surgical adhesions but could have advantages if performed at the time of transplantation. We investigated a method of brief-interval staging combining LT and sleeve gastrectomy (SG). LT recipients with a body mass index (BMI) > 40 kg/m 2 received an SG during the same hospitalization as the LT (LT/SG), at the same time as a planned brief-interval return to the operating room for biliary anastomosis. Differences in intraoperative attributes of the LT (Stage 1) versus SG (Stage 2) procedures were analyzed using Wilcoxon signed-rank test with significance p  < 0.05 and compared with patients with obesity having a two-stage LT without SG. A total of 14 cases {median MELD score 33 (interquartile range [IQR], 18-40)} were compared with 28 controls; 60% were critically ill prior to surgery with mechanical ventilation, vasopressors, or continuous renal replacement therapy. Median interval between procedures was 16.1 (IQR, 12.5-22.7) hours for cases and 12.2 (IQR, 11.1-16.6) hours for controls, p  = 0.27. Median BMI at LT/SG was 47.0 (IQR, 41.7-51.3) kg/m 2 versus 38.1 (IQR, 35.7-39.8) kg/m 2 for controls, p  < 0.001. At 1 year, median excess body weight loss was 74.0% (IQR, 46.2%-78.7%) in cases and 15.8% (IQR, -5.4% to 62.6%) in controls, p  = 0.13; total weight loss was 38.1% (IQR, 23.9-42.9) in cases versus 7.7% (IQR, -2.4% to 27.6%) for controls, p  = 0.03. Graft survival at 1 year was 92.9% for cases and 89.3% for controls with similar early postoperative outcomes. This proof-of-concept study revealed that a brief-interval SG during LT is feasible in patients with high MELD and resulted in sustained weight loss at 1 year with similar graft survival. Further studies are needed to determine an optimal strategy.

Prospective Assessment of the Prevalence of Enter Hyperoxalosis in Kidney Transplant Candidates

Enteric hyperoxalosis (EH) is an emerging cause of kidney transplantation (KT) dysfunction. We sought to determine the prevalence of EH and factors that affect plasma oxalate (POx) among at-risk KT candidates.

Methods

We prospectively measured POx among KT candidates evaluated at our center from 2017 to 2020 with risk factors for EH namely bariatric surgery, inflammatory bowel disease, or cystic fibrosis. EH was defined by a POx ≥10 μmol/L. Period-prevalence of EH was calculated. We compared mean POx across 5 factors: underlying condition, chronic kidney disease (CKD) stage, dialysis modality, phosphate binder type, and body mass index.

Results

Of 40 KT candidates screened, 23 had EH for a 4-y period prevalence of 58%. Mean POx was 21.6 ± 23.5 μmol/L ranging from 0 to 109.6 μmol/L. 40% of screened had POx >20 μmol/L. Sleeve gastrectomy was the most common underlying condition associated with EH. Mean POx did not differ by underlying condition (P = 0.27), CKD stage (P = 0.17), dialysis modality (P = 0.68), phosphate binder (P = 0.58), and body mass index (P = 0.56).

Conclusions

Bariatric surgery and inflammatory bowel disease were associated with a high prevalence of EH among KT candidates. Contrary to prior studies, sleeve gastrectomy was also associated with hyperoxalosis in advanced CKD. POx concentrations observed in EH reached levels associated with tissue and potentially allograft deposition. Concentrations can be as high as that seen in primary hyperoxaluria. More studies are needed to assess if POx is indeed a modifiable factor affecting allograft function in patients with EH.

Retrospective analysis of the impact of severe obesity on kidney transplant outcomes

BACKGROUND

The prevalence of obesity among kidney transplant recipients is rising. We sought to determine the association between recipient body mass index (BMI) and post-transplant complications.

METHODS

Single-center, retrospective cohort study of all adult kidney transplant recipients from 2004 to 2020. Recipients were stratified into four BMI categories: normal-weight (BMI 18.5-24.9 kg/m2, n = 1020), overweight (BMI 25-29.9 kg/m2, n = 1002), moderately obese (BMI 30-34.9 kg/m2, n = 510) and severely-to-morbidly obese (BMI ≥35 kg/m2, n = 274). Logistic regression was used to estimate the association between BMI category and surgical site infections (SSIs).

RESULTS

Recipients with BMI ≥35 kg/m2 had significantly higher rates of SSIs (P < .0001) compared with recipients in all other categories. On multivariable analysis, recipients with BMI ≥35 kg/m2 had increased odds of SSIs compared with normal-weight recipients [odds ratio (OR) 3.34, 95% confidence interval (CI) 1.55-7.22, P = .022). On multivariable and Kaplan-Meier analyses, no BMI groups demonstrated increased odds for death-censored graft failure.

CONCLUSION

Severe obesity in kidney transplant recipients is associated with increased SSIs, but not kidney allograft failure.

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.

Options for approaches to nephrectomy in patients with end-stage chronic kidney disease caused by autosomal dominant polycystic kidney disease: A review

Autosomal-dominant polycystic kidney disease is a common kidney disease that affects all racial groups around the world, occupies one of the leading places in the structure of urological diseases and forms a significant contribution to the structure of all causes leading to the end stage of chronic renal failure, disabling patients in this group and hence leading to the inevitability of renal replacement therapy. A highly effective clinical method for replacing lost kidney function is kidney transplantation. Based on the fact that the number of patients with this pathology is increasing, it is necessary to search for and introduce clear criteria for the best care, taking into account the high likelihood of developing infectious complications, hematuria, the absence or presence of diuresis, arterial hypertension in this category of patients. The article reflects the various methods of nephrectomy in patients suffering from autosomal dominant polycystic kidney disease, as well as how approaches to nephrectomy have evolved. The results of complications, as well as patient and graft survival in domestic and foreign studies, in which bilateral or ipsilateral nephrectomy was used using open or laparoscopic access before, during or after kidney transplantation, are demonstrated. Preference is rightfully given to minimally invasive methods of surgical treatment. Taking into account the already reduced resources of the organism of these patients, the volume and method of surgical treatment should be carefully chosen, taking into account safety, efficacy and risk minimization.

The effect of calcineurin inhibitors on anthropometric measurements in kidney transplant recipients

Background

This study was designed to investigate the effect of calcineurin inhibitors (CNIs), cyclosporine (CsA), and tacrolimus (Tac) on anthropometrics in kidney transplant recipients.

Methods

111 of 128 adult kidney transplant recipients who received post-transplant CNIs were included in this retrospective study. Anthropometrics were recorded in the pre-transplant and post-transplant 4-year follow-up periods (1st, 3rd, 6th, 12th, 24th, 36th and 48th months).

Results

Compared to pre-transplant values, significant increases in body weight and body mass index (between 3rd and 48th months), waist and hip circumferences (between 1st and 48th months), waist-to-hip ratio (between 1st and 3rd or 6th months) and neck circumference (between 1st and 12th or 24th months) were observed in both CsA and Tac groups. A significant increase was noted in post-transplant body fat percentage values for the 3rd to 24th months in the CsA group, whereas for the 24th to 48th months in both CsA and Tac groups. Hip circumferences percentage changes from the pre-transplant period to the 1st, 12th and 24th months were significantly higher in CsA than in the Tac group. At each time point, there was no significant difference in percentage changes for other anthropometric parameters between the CsA and Tac groups. De novo diabetes mellitus developed in 8.3% of the CsA group and 19.1% of the Tac group.

Conclusions

After a successful kidney transplant, anthropometric measurements increase in most recipients. Although the effect of calcineurin inhibitor type on weight gain is unclear, a regression analysis showed that CNI type was not a risk factor for the development of obesity in the 48th month. However, it is helpful to be cautious about its dyslipidemic effect in patients using CsA and the potential hazards of using Tac in patients with a diabetic predisposition.

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.

The Impact of Obesity and Associated Comorbidities on the Outcomes after Renal Transplantation with a Living Donor vs. Deceased Donor Grafts

Background: Obesity among kidney transplant (KT) recipients can lead to metabolic comorbidity-associated deaths. This study compares post-KT survival between obese and non-obese patients and outcomes of living donor (LD) and deceased donor (DD) grafts. Methods: Between January 2005−May 2019, 1403 KT recipients from a single center were included in the study, as well as 314 patients (22.4%) with obesity (BMI > 30 kg/m2), 137 DD transplants, and 177 LD transplants. Of the 1089 (77.6%) in the control group (BMI ≤ 30 kg/m2), 384 were DD transplants and 705 LD transplants. The Kaplan−Meier method was used for survival analysis and a Cox regression was used to identify risk factors for graft loss and mortality. Propensity score matching analysis adjusting for age, IHD, and T2DM was performed. Results: The study group had higher incidence of obesity related comorbidities, delayed graft function and primary non function (p < 0.001). One-, 5-and 10-year patient and graft survival were lower in the study group (p < 0.001). Subgroup analysis of graft survival according to type of graft shows a difference in the DD (p = 0.002) but not in the LD group (p = 0.220). However, mortality was higher in both groups (LD, p = 0.045; DD, p = 0.004). Risk factors for mortality were age, T2DM, IHD, and DD, and for graft failure: IHD, BMI, donor age, re-transplant, and DD. Propensity score analysis shows an odds ratio of 0.81 for graft failure and 0.93 for death in the study group (95% CI = 0.55, 1.21, p = 0.3 and CI = 0.59, 1.46, p = 0.7, respectively). Conclusions: Recipient age and metabolic comorbidities should be emphasized when evaluating patients with obesity. We suggest considering weight loss interventions using the new GLP-1 inhibitors and bariatric procedures in selected patients to prepare overweight patients for transplant.

Taurodeoxycholic acid and valine reverse obesity-associated augmented alloimmune responses and prolong allograft survival

Obesity initiates a chronic inflammatory network linked to perioperative complications and increased acute rejection rates in organ transplantation. Bariatric surgery is the most effective treatment of obesity recommended for morbidly obese transplant recipients. Here, we delineated the effects of obesity and bariatric surgery on alloimmunity and transplant outcomes in diet-induced obese (DIO) mice. Allograft survival was significantly shorter in DIO-mice. When performing sleeve gastrectomies (SGx) prior to transplantation, we found attenuated T cell-derived alloimmune responses resulting in prolonged allograft survival. Administering taurodeoxycholic acid (TDCA) and valine, metabolites depleted in DIO-mice and restored through SGx, prolonged graft survival in DIO-mice comparable with SGx an dampened Th1 and Th17 alloimmune responses while Treg frequencies and CD4+ T cell-derived IL-10 production were augmented. Moreover, in recipient animals treated with TDCA/valine, levels of donor-specific antibodies had been reduced. Mechanistically, TDCA/valine restrained inflammatory M1-macrophage polarization through TGR5 that compromised cAMP signaling and inhibited macrophage-derived T cell activation. Consistently, administering a TGR5 agonist to DIO-mice prolonged allograft survival. Overall, we provide novel insights into obesity-induced inflammation and its impact on alloimmunity. Furthermore, we introduce TDCA/valine as a noninvasive alternative treatment for obese transplant patients.

Recipient obesity as a risk factor in kidney transplantation

Background

The aim of the study was to investigate the effect of recipient obesity on the short- and long-term outcomes of patients undergoing primary kidney transplantation (KT).

Patients and methods

A total of 578 patients receiving primary KT in our department between 1993 and 2017 were included in the study. Patients were divided according to their body mass index (BMI) into normal weight (BMI 18.5–24.9 kg/m²; N = 304), overweight (BMI 25–29.9 kg/m²; N = 205) and obese (BMI ≥ 30 kg/m²; N = 69) groups. Their clinicopathological characteristics, outcomes, and survival rates were analyzed retrospectively.

Results

Obesity was associated with an increased rate of surgical complications such as wound infection (P < 0.001), fascial dehiscence (P = 0.023), and lymphoceles (P = 0.010). Furthermore, the hospital stay duration was significantly longer in the groups with obese patients compared to normal weight and overweight patients (normal weight: 22 days, overweight: 25 days, and obese: 33 days, respectively; P < 0.001). Multivariate analysis showed that recipient obesity (BMI ≥ 30) was an independent prognostic factor for delayed graft function (DGF) (OR 2.400; 95% CI, 1.365–4.219; P = 0.002) and postoperative surgical complications (OR 2.514; 95% CI, 1.230–5.136; P = 0.011). The mean death-censored graft survival was significantly lower in obese patients (normal weight: 16.3 ± 0.6 years, overweight: 16.3 ± 0.8 years, obese 10.8 ± 1.5 years, respectively; P = 0.001). However, when using the Cox proportional hazards model, the association between recipient obesity and death-censored renal graft failure disappeared, after adjustment for important covariates, whereas the principal independent predictors of graft loss were recipient diabetes mellitus and hypertension and kidneys from donors with expanded donor criteria.

Conclusion

In conclusion, obesity increases the risk of DGF and post-operative surgical complications after primary KT. Appropriate risk-adapted information concerning this must be provided to such patients before KT. Furthermore, obesity-typical concomitant diseases seem to negatively influence graft survival and need to be considered after the transplantation of obese patients.

Effects of obesity and weight-loss surgery shift the microbiome and impact alloimmune responses

PURPOSE OF REVIEW

Obesity is a worldwide health problem with increasing rates in both children and adults. Bariatric surgery (BS) represents the only effective long-term treatment. Beneficial effects of BS may be mediated through shifts of the gut microbiome. Here, we introduce data linking the microbiome to alloimmune responses.

RECENT FINDINGS

The rapid development of microbiome sequencing technologies in addition to the availability of gnotobiotic facilities have enabled mechanistic investigations on modulations of alloimmune responses through microbiomes. BS has been shown to improve comorbidities and chronic inflammation caused by obesity. Changes in microbiota and microbiota-related metabolites may play a role. Patients either listed or having received a transplant have undergone weight loss surgery, thus allowing to dissect mechanisms of microbial shifts to alloimmunity.

SUMMARY

Weight loss and BS have the potential to improve transplant outcomes by ameliorating alloimmune responses. Those effects may be carried out through alterations of the gut microbiome.

Association of obesity with mortality and clinical outcomes in children and adolescents with transplantation: A systematic review and meta-analysis

Obesity might be associated with mortality and clinical outcomes following transplantation; however, the direction of this relationship has not been well-recognized in youth. The aim of this systematic review and meta-analysis was to investigate the association of obesity with post-transplant mortality and clinical outcomes in children and adolescents. Following a systematic search of observational studies published by December 2018 in PubMed, Scopus, Embase, and Cochrane library, 15 articles with total sample size of 50,498 patients were included in the meta-analysis. The main outcome was mortality and secondary outcomes included acute graft versus host disease (GVHD), acute rejection, and overall graft loss. The pooled data analyses showed significantly higher odds of long term mortality (OR 1.30, 95% CI 1.15-1.48, P < 0.001, I² = 50.3%), short term mortality (OR 1.79, 95% CI 1.19-2.70, P = 0.005, I² = 59.6%), and acute GVHD (OR 2.13, 95% CI 1.5-3.02, P < 0.001, I² = 1.7%) in children with obesity. There were no significant differences between patients with and without obesity in terms of acute rejection (OR 1.07, 95% CI 0.98-1.16, P = 0.132, I² = 7.5%) or overall graft loss (OR 1.04, 95% CI 0.84-1.28, P = 0.740, I² = 51.6%). This systematic review and meta-analysis has stated higher post-transplant risk of short and long term mortality and higher risk of acute GVHD in children with obesity compared to those without obesity. Future clinical trials are required to investigate the effect of pre-transplant weight management on post-transplant outcomes to provide insights into the clinical application of these findings. This may in turn lead to establish guidelines for the management of childhood obesity in transplantations.

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.

Bariatric surgery prior to transplantation and risk of early hospital re-admission, graft failure, or death following kidney transplantation

Bariatric surgery has been shown to be safe in the dialysis population. Whether bariatric surgery before kidney transplantation influences posttransplant outcomes has not been examined nationally. We included severely obese (BMI >35) dialysis patients between 18 and 70 years who received a kidney transplant according to the US Renal Data System. We determined the association between history of bariatric surgery and risk of 30-day readmission, graft failure, or death after transplantation using multivariable logistic, Fine-Gray, and Cox models. We included 12 573 patients, of whom 503 (4%) received bariatric surgery before transplantation. Median age at transplant was 53 years; 42% were women. Overall, history of bariatric surgery was not statistically significantly associated with graft failure (HR 1.02; 95% CI 0.77-1.35) or death (HR 1.10; 95% CI 0.84-1.45). However, sleeve gastrectomy (vs. no bariatric surgery) was associated with lower risk of graft failure (HR 0.39; 95% CI 0.16-0.95). In conclusion, history of bariatric surgery prior to kidney transplantation was not associated with allograft or patient survival, but findings varied by surgery type. Sleeve gastrectomy was associated with better graft survival and should be considered in severely obese transplant candidates receiving dialysis.

Obesity Management in Kidney Transplant Candidates: Current Paradigms and Gaps in Knowledge

In this review, we discuss the increasing prevalence of obesity among people with chronic and end-stage kidney disease (ESKD) and implications for kidney transplant (KT) candidate selection and management. Although people with obesity and ESKD receive survival and quality-of-life benefits from KT, most KT programs maintain strict body mass index (BMI) cutoffs to determine transplant eligibility. However, BMI does not distinguish between visceral adiposity, which confers higher cardiovascular risks and risks of perioperative and adverse posttransplant outcomes, and muscle mass, which is protective in ESKD. Furthermore, requirements for patients with obesity to lose weight before KT should be balanced with the findings of numerous studies that show weight loss is a risk factor for death among patients with ESKD, independent of starting BMI. Data suggest that KT is associated with survival benefits relative to remaining on dialysis for candidates with obesity although recipients without obesity have higher delayed graft function rates and longer transplant hospitalization durations. Research is needed to determine the optimal body composition metrics for KT candidacy assessments and risk stratification. In addition, ESKD-specific obesity management guidelines are needed that will address the neurologic, behavioral, socioeconomic, and physical underpinnings of this increasingly common disease.

Impact of obesity in kidney transplantation: a prospective cohort study from French registries between 2008 and 2014

BACKGROUND

The access of obese patients to kidney transplantation is limited despite several studies showing that obese transplant recipients had a better survival rate than those undergoing dialysis. The aim of this study was to compare patient and graft survival rates and post-renal transplant complications in obese patients and non-obese patients and to assess the effect of pre-transplant weight loss in obese patients on transplant outcomes.

METHODS

We carried out a prospective cohort study using two French registries REIN and CRISTAL on 7 270 kidney transplant patients between 2008 and 2014 in France. We compared obese patients with non-obese patients and obese patients who lost more than 10% of weight before the transplant (Obese WL and Obese nWL).

RESULTS

The mean BMI in our obese patients was 32 kg/m2. Graft survival was lower in obese patients than in non-obese patients (HR = 1.40, IC 95% [1.09; 1.78], P = 0.007) whereas patient survival was similar (HR = 0.94, IC 95% [0.73; 1.23], P = 0.66). Graft survival was significantly lower in Obese WL than in Obese nWL (HR = 2.17, CI 95% [1.02; 4.63], P = 0.045) whereas patient survival was similar in the two groups (HR = 0.79, IC 95% [0.35; 1.77], P = 0.56).

CONCLUSION

Grade I obesity does not seem to be a risk factor for excess mortality after kidney transplantation and should not be an obstacle to having access to a graft. Weight loss before a kidney transplant in this patients should not be essential for registration on waiting list.

Robot-assisted kidney transplantation is a safe alternative approach for morbidly obese patients with end-stage renal disease

BACKGROUND

Many centres deny obese patients with a body mass index (BMI) >35 access to kidney transplantation due to increased intraoperative and postoperative complications.

METHODS

From August 2017 to December 2019, 73 consecutive cases of kidney transplantation in morbidly obese patients were enrolled at a single university at the initiation of a robotic transplant surgery program. Outcomes of patients who underwent robotic assisted kidney transplant (RAKT) were compared to frequency-matched patients undergoing open kidney transplant (OKT).

RESULTS

A total of 24 morbidly obese patients successfully underwent RAKT, and 49 obese patients received an OKT. The RAKT group developed fewer surgical site infections (SSI) than the OKT group. Graft function, creatinine, and glomerular filtration rate (GFR) were similar between groups 1 year after surgery. Graft and patient survival were 100% for both groups.

CONCLUSIONS

RAKT offers a safe alternative for morbidly obese patients, who may otherwise be denied access to OKT.

Bariatric surgery in transplant recipients: A narrative review

Morbidity and mortality rates are increased due to obesity after organ transplantation; in this regards, bariatric surgery (BS) is believed to be an effective treatment for posttransplant obese patients. Nevertheless, some studies are doubtful in terms of the effectiveness of BS, the most suitable bariatric procedure, and management of immunosuppressant drugs in some kinds of organ transplants. We evaluated nonsurgical therapies, weight reduction, adjustment of immunosuppressants, comorbidities, and the recommended surgical procedures for posttransplant BS for different types of organ transplantations.

Factor Analysis for Body Mass Index Changes in Kidney Transplant Recipients

BACKGROUND

The purpose of this study was to identify factors influencing changes in the body mass index (BMI) of kidney transplant (KT) patients and provide data for the management of the BMI of patients who have undergone KT.

METHOD

The participants were 106 patients who underwent KT at a single center from August 2014 to June 2017. BMIs were compared and analyzed for 6 months and 24 months after KT, and the survey details were collected through medical records. Analysis was performed between 2 groups, one with increased BMI and the other without. Multivariate logistic regression analysis was performed to identify the factors related to an increase in BMI.

RESULTS

BMI increased from 22.60 ± 2.72 kg/m² at 6 months to 23.18 ± 3.06 kg/m² 2 years after KT. The group with increased BMI (n = 39) had more patients with higher low-density cholesterol levels at the time of KT (low-density cholesterol ≥100 mg/dL; 34 [54.0%] vs 10 [26.3]; P = .008) and without statin drug use than the other group (n = 67) (statin drug use, 48 [70.6%] vs 34 [87.2%], P = .044). Multiple logistic regression analysis showed that age >50 years (odds ratio [OR] = 2.942; 95% confidence interval [CI], 1.075-8.055; P = .036), low-density lipoprotein >100 mg/dL at KT (OR = 6.618; 95% CI, 2.225-19.682; P = 0.001), and no statin drugs (OR = 5.094; 95% CI, 1.449-17.911, P = .011) were the risk factors for an increased BMI after KT.

CONCLUSIONS

After KT, to prevent an increase in the BMI, clinicians should strongly recommend the use of drugs to treat hyperlipidemia, especially in elderly patients with high low-density lipoprotein levels before KT.

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.

Poor kidney graft survival in anorexia nervosa patients

BACKGROUND

Anorexia nervosa is a condition associated with poor outcomes in a variety of circumstances such as recurrence of eating disorders, psychiatric disorders, and organ damage.

OBJECTIVE

In the present study, we first sought to determine the 5-year kidney graft survival in patients with anorexia nervosa and then to evaluate the BMI course and medical complications.

METHODS

In this multicenter, retrospective, case-control study, we analyzed the impact of anorexia nervosa on graft outcomes compared to transplant recipients with low or normal BMI.

RESULTS

We enrolled 137 women in this study: 19 with anorexia nervosa, 59 with low BMI (BMI < 18.5 kg/m²), and 59 with normal BMI (18.5-24.9 kg/m²). Anorexia nervosa was significantly associated with lower graft survival compared to either of the other groups (hazard ratio 5.5 [95% CI 3.4-8.9], p = 0.005); there was no difference in graft survival between patients with low or normal BMI. Cardiovascular complications were more frequent in the anorexia nervosa group (37%) than in patients with low (6%) or normal BMI (7%) (p = 0.001).

CONCLUSION

We conclude that patients with anorexia nervosa should be considered a high-risk group.

LEVEL OF EVIDENCE

Level III, evidence obtained from well-designed cohort or case-control analytic studies.

Obesity in Renal Transplantation

BACKGROUND

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

SUMMARY

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

Effectiveness of Bariatric Surgery in Increasing Kidney Transplant Eligibility in Patients with Kidney Failure Requiring Dialysis

PURPOSE

Severe obesity can increase risk of complications after kidney transplantation. There is a paucity of literature on bariatric surgery outcomes in renal transplant candidates. The objective of this study was to analyze outcomes of bariatric surgery as a weight reduction strategy for patients with kidney failure to enhance eligibility for kidney transplantation.

MATERIALS AND METHODS

We performed a retrospective analysis of the Metabolic and Bariatric Surgery Accreditation and Quality Improvement Program database at a single institution for patients with chronic kidney disease receiving hemodialysis therapy (CKD G5D) undergoing bariatric surgery between 2011 and 2018.

RESULTS

Of 2363 patients who underwent bariatric surgery, 38 (1.6%) had CKD G5D; median age (range) was 49 years (33; 69), 52.6% were female, and mean BMI was 44.2 kg/m². Twenty-four patients underwent laparoscopic Roux-en-Y gastric bypass (LRYGB), and 14 patients underwent laparoscopic sleeve gastrectomy. Seventeen patients (46%, n=37) had a BMI≤35 at 6 months, while 25 patients (75.8%, n=33) achieved a BMI≤35 at 12 months. Of these, 18 patients (47%) were listed for kidney transplant, and 8 patients (21%) received kidney transplant. There was no statistically significant difference between sleeve and LRYGB procedures in patients who reached BMI of 35 at 12 months (P=0.58). Median length of stay was 2.3 days. Thirty-day readmission rate was 2 patients (5.3%), and 2 patients (5.3%) required reoperation (one for bleeding, one for acute recurrent hiatal hernia). No mortality occurred.

CONCLUSION

Laparoscopic bariatric surgery offers effective weight loss for CKD G5D patients to achieve transplant eligibility with acceptable outcomes.

Impact of high body mass index on allograft outcomes in kidney transplant recipients with presensitization to human leukocyte antigen

Background

This study aimed to investigate whether high body mass index (BMI) and presensitization to human leukocyte antigen (HLA) in kidney transplant recipients (KTRs) affected allograft outcomes.

Methods

From January 2010 to December 2018, 1,290 kidney transplantations (KTs) were performed at the Seoul St Mary’s Hospital. Of these, 682 cases of ABO-compatible living donor KT patients were enrolled. They were divided into four groups (low BMI-non-sensitized, high BMI-non-sensitized, low BMI-sensitized, and high BMI-sensitized) according to the median BMI value (22.7 kg/m²) and HLA presensitization status (anti-HLA antibody mean fluorescence intensity > 3,000). Short-term and long-term allograft outcomes were compared between groups.

Results

In the high BMI-sensitized group, the decline in allograft function was higher than that in the other three groups. Death-censored graft loss (DCGL) rates were highest in the high BMI-sensitized group (4 of 21 [19.0%], p = 0.04). In the multivariable Cox regression hazard regression model analysis, the hazard ratio (HR) for DCGL was intensified when high BMI and presensitization statuses were combined (HR, 3.75; p = 0.03); these statuses significantly interacted with each other (p-value for interaction = 0.008).

Conclusion

Our results suggest that presensitization to HLA and high BMI might have an interactive adverse impact on allograft outcomes in KTRs.

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.

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.

Metabolic Consequences of Solid Organ Transplantation

Metabolic complications affect over 50% of solid organ transplant recipients. These include posttransplant diabetes, nonalcoholic fatty liver disease, dyslipidemia, and obesity. Preexisting metabolic disease is further exacerbated with immunosuppression and posttransplant weight gain. Patients transition from a state of cachexia induced by end-organ disease to a pro-anabolic state after transplant due to weight gain, sedentary lifestyle, and suboptimal dietary habits in the setting of immunosuppression. Specific immunosuppressants have different metabolic effects, although all the foundation/maintenance immunosuppressants (calcineurin inhibitors, mTOR inhibitors) increase the risk of metabolic disease. In this comprehensive review, we summarize the emerging knowledge of the molecular pathogenesis of these different metabolic complications, and the potential genetic contribution (recipient +/- donor) to these conditions. These metabolic complications impact both graft and patient survival, particularly increasing the risk of cardiovascular and cancer-associated mortality. The current evidence for prevention and therapeutic management of posttransplant metabolic conditions is provided while highlighting gaps for future avenues in translational research.

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

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

Nutritional status in kidney transplant patients before and 6-month after transplantation: Result of PNSI study

OBJECTIVES

Kidney transplantation is an essential treatment in management of kidney failure patients. The present study evaluated and compared the nutritional status of renal transplant patients before and 6 months after kidney transplantation and in comparison with healthy individuals.

METHODS

A multi-center, case-control study was conducted among 40 kidney transplant recipients and 40 healthy adults. Biochemical tests, anthropometric indices, and dietary intake were collected at baseline and 6 months post-transplant and compared with healthy controls.

RESULTS

Anthropometric indices of the participants increased in post-transplant period compared to baseline (p < 0.05). The calories, fat, carbohydrates, and selenium intakes also increased in patients compared to before transplantation and healthy controls. The mean score of malnutrition index in patients, before transplantation were: good nutrition status (A) = 42.5%, mild to moderate malnutrition (B) = 52.5%, and severe malnutrition (C) = 5%, that changed to A = 75%, B = 20%, and C = 5% six months after surgery. The mean score of malnutrition index in pre-transplant patients were: A = 42.5%, B = 52.5% and, C = 5%, which changed to A = 75%, B = 20% and C = 5% after 6 months. Experimental results showed that mean plasma levels of albumin, total protein, calcium increased as well as mean plasma levels of magnesium and phosphorus decreased over six months (p < 0.001).

CONCLUSION

Kidney transplantation led to improvement in clinical and nutritional status of patients with renal failure. Improving dietary intakes as part of the medical care process can help improve their medical conditions.

Management of metabolic alterations in adult kidney transplant recipients: A joint position statement of the Italian Society of Nephrology (SIN), the Italian Society for Organ Transplantation (SITO) and the Italian Diabetes Society (SID)

Chronic metabolic alterations such as post-transplant diabetes mellitus (PTDM), dyslipidaemias and overweight/obesity significantly impact on kidney transplant (KT) outcomes. This joint position statement is based on the evidence on the management of metabolic alterations in KT recipients (KTRs) published after the release of the 2009 KDIGO clinical practice guideline for the care of KTRs. Members of the Italian Society of Nephrology (SIN), the Italian Society for Organ Transplantation (SITO) and the Italian Diabetes Society (SID) selected to represent professionals involved in the management of KTRs undertook a systematic review of the published evidence for the management of PTDM, dyslipidaemias and obesity in this setting. The aim of this work is to provide an updated review of the evidence on the prevention, diagnosis and treatment of metabolic alterations in KTRs, in order to support physicians, patients and the Healthcare System in the decision-making process when choosing among the various available options.

Study of weight and body mass index on graft loss after transplant over 5 years of evolution

Patients frequently experience a weight gain after organ transplantation. This increase in weight is the result of multiple factors, and is usually intensified by glucocorticoids and immunosuppressive drugs. It can also delay graft function and cause serious health problems. The objective of this study was to study the obesity as well as its causes and consequences in kidney transplant patients. The sample population consisted of 282 renal transplant patients, 170 men and 112 women, 18-74 years of age, who were monitored over a period of five years. For the purposes of our research, the patients were divided into two groups: (1) normal weight 18.5 ≤ BMI <25; (2) overweight 25 ≤ BMI ≤30. The association between BMI as an independent variable and graft survival was determined by means of a Cox regression analysis. Overweight patients were characterized by a higher comorbidity prevalence. In the Cox multivariate analysis, the initial BMI, evaluated as a continuous variable continued to be an independent predictor of delayed graft function and chronic nephropathy. This study evaluated the BMI as a continuous value instead of a categorical value. In conclusion, our results suggest that an increase in BMI without categorical variation can be an independent risk factor for graft loss. Consequently, obesity prevention for renal transplant patients should include dietary counseling and management, moderate physical activity, and steroid minimization.