Effects of Obesity on Postoperative Complications and Graft Survival After Kidney Transplantation

Metabolic and Bariatric Operation and the Path to Kidney Transplantation

BACKGROUND

Obesity is a significant barrier to kidney transplantation for patients with end-stage renal disease (ESRD). We aimed to evaluate the long-term impact of metabolic and bariatric surgery (MBS) on kidney transplantation access and outcomes in individuals with obesity and patients with ESRD.

STUDY DESIGN

A retrospective cohort study using data from 64 US healthcare organizations included 132,989 individuals with obesity (BMI ≥ 30 kg/m²) and ESRD requiring dialysis, of whom 6,263 (4.6%) underwent MBS. Propensity score matching produced 1:1 matched groups of 6,238 patients each, analyzed for 10 years. Primary outcomes included rates of kidney transplant waitlist placement, transplantation, and overall mortality. Secondary outcomes focused on 22,979 transplant recipients, including 1,701 (7.4%) patients who underwent MBS, to evaluate posttransplant adverse events.

RESULTS

During a median follow-up of 33.3 months (MBS) and 28.5 months (controls), patients who underwent MBS demonstrated higher rates of waitlist placement (19.12% vs 10.53%, hazard ratio [HR] 1.800, 95% CI 1.636 to 1.980, p < 0.001) and transplantation (27.06% vs 16.09%, HR 1.712, 95% CI 1.584 to 1.852, p < 0.001) at 10 years, with benefits evident within 1-month postoperation. Mortality was lower in the MBS group (30.55% vs 36.44%, HR 0.768, 95% CI 0.723 to 0.817, p < 0.001). In transplant recipients, patients who underwent MBS had lower cardiovascular complications (37.3% vs 40.6%, risk ratio 0.92, p = 0.007) and all-cause mortality (16.70% vs 20.88%, HR 0.82, p < 0.001), with no significant differences in graft rejection or failure.

CONCLUSIONS

MBS significantly improves access to kidney transplantation and long-term survival for obese patients with ESRD. Patients who underwent MBS demonstrated notable improvements in cardiovascular health, potentially leading to a better quality of life and survival. These findings suggest that MBS should be considered as part of the comprehensive care for this high-risk population.

Long term surgical outcomes following renal transplantation in Aotearoa New Zealand: the South Island Chapter

BACKGROUND

Over the last decade, there has been a steady increase in the number of patients diagnosed with end stage renal failure (ESRF). Renal transplant remains the best available treatment for ESRF. The aim of this study is to assess the surgical outcomes following renal transplantation in a single tertiary centre in Aotearoa New Zealand.

METHODS

A retrospective observational study was performed in Christchurch Hospital. All live-related and deceased donor adult renal transplants performed between 1 January 2009 and 1 January 2023 were included in the study. Patients were identified from the local transplant database (Proton) and data were extracted from both electronic and hardcopy records.

RESULT

There were 227 live-related and 150 deceased donor renal transplants performed over the study period. Median BMI in the study cohort was 27 kg/m2. The most common aetiology of ESRF was glomerular disease. Obese (BMI 30-40 kg/m2) patients had a higher incidence of post-operative complications. Ethnicity was shown to be associated with a higher incidence of post-operative complications. This was only statistically significant in the Pacific Islander group (P = 0.013). Live-related donor graft survival was 97% at 1 year and 93% at 5 years while deceased donor graft survival was 95% at 1 year and 92% at 5 years.

CONCLUSION

This study showed that graft outcome in our cohort was comparable to international data. However, further studies are needed to assess whether specific ethnic groups are truly linked to a higher incidence of post-operative complications.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

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.

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.

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

Associations between body mass index and all-cause mortality: A systematic review and meta-analysis

Fasting insulin and c-reactive protein confound the association between mortality and body mass index. An increase in fat mass may mediate the associations between hyperinsulinemia, hyperinflammation, and mortality. The objective of this study was to describe the "average" associations between body mass index and the risk of mortality and to explore how adjusting for fasting insulin and markers of inflammation might modify the association of BMI with mortality. MEDLINE and EMBASE were searched for studies published in 2020. Studies with adult participants where BMI and vital status was assessed were included. BMI was required to be categorized into groups or parametrized as non-first order polynomials or splines. All-cause mortality was regressed against mean BMI squared within seven broad clinical populations. Study was modeled as a random intercept. β coefficients and 95% confidence intervals are reported along with estimates of mortality risk by BMIs of 20, 30, and 40 kg/m2 . Bubble plots with regression lines are drawn, showing the associations between mortality and BMI. Splines results were summarized. There were 154 included studies with 6,685,979 participants. Only five (3.2%) studies adjusted for a marker of inflammation, and no studies adjusted for fasting insulin. There were significant associations between higher BMIs and lower mortality risk in cardiovascular (unadjusted β -0.829 [95% CI -1.313, -0.345] and adjusted β -0.746 [95% CI -1.471, -0.021]), Covid-19 (unadjusted β -0.333 [95% CI -0.650, -0.015]), critically ill (adjusted β -0.550 [95% CI -1.091, -0.010]), and surgical (unadjusted β -0.415 [95% CI -0.824, -0.006]) populations. The associations for general, cancer, and non-communicable disease populations were not significant. Heterogeneity was very large (I2  ≥ 97%). The role of obesity as a driver of excess mortality should be critically re-examined, in parallel with increased efforts to determine the harms of hyperinsulinemia and chronic inflammation.

Obesity and Kidney Transplant Candidates: An Outcome Analysis Based on Body Mass Index

Background Obesity is a well-established risk factor for a decline in renal function and post-operative complications. Also, obese patients suffer worse outcomes such as higher rates of wound complications, longer hospital stays, and delayed graft function (DGF) when compared to nonobese patients. The correlation between having a high BMI and the postoperative outcomes of kidney transplantation has not been investigated yet in Saudi Arabia. There is scarce evidence that patients with obesity who have undergone kidney transplantation are devoid of any complications before, during, or after their procedure. Methodology A retrospective cross-sectional study was conducted using charts of nearly 142 patients in King Abdullah Specialist Children's Hospital in Riyadh, who had kidney transplant surgery in the organ transplantation department. All Obese patients with BMI >29.9 who underwent Kidney Transplant Surgery in King Abdulaziz Medical City from 2015 to 2022 were used. Details of hospital admissions were retrieved. Results A total of 142 patients fulfilling the inclusion criteria were included. There was a significant difference between patients regarding pre-surgical history where all cases (100%; 2) with class three obesity were hypertensive and on dialysis versus (77.8%; 21) and (70.4%; 19) of class two obesity and (86.7%; 98) and (78.8%; 89) of class one obesity cases, respectively (P = 0.041). Regarding medical history, hypertension was reported among 121 (85%), followed by dialysis (77%; 110), diabetes mellitus (DM) (52%; 74), dyslipidemia (24%; 35), endocrine diseases (15%; 22), and cardiovascular diseases (16%; 23). Considering post-transplant complications, 14.1% (20) of the study cases had DM (16.8% of obese class one, 3.7% of obese class two, and none of obese class three; P = 0.996) and urinary tract infection (UTI) among 7% (10) of the cases (6.2% of obese class one, 11.1% of obese class two, and none of obese class three; P = 0.996). All these differences according to patients' BMI were statistically insignificant. Conclusion Obese patients are more likely to experience difficult intraoperative management along with a complicated postoperative course due to numerous concomitant comorbidities. Post-transplant DM (PTDM) was the most prominent post-transplant complication followed by UTI. A remarkable reduction in serum creatinine and blood urea nitrogen (BUN) has been observed at the time of discharge and after six months compared to pre-transplant measurements.

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.

Implications for body weight extremes in solid organ transplantation

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