Morbid obesity and functional status as predictors of surgical complication after renal transplantation

Surgical Complications Following Renal Transplantation in a Large Institutional Cohort

Background

Successful renal transplantation (RTx) relies on immunosuppression and an optimal surgical course with few surgical complications. Studies reporting the postoperative complications after RTx are heterogeneous and often lack systematic reporting of complications. This study aims to describe and identify postoperative short-term and long-term complications after RTx in a large institutional cohort and identify risk factors for a complicated surgical course.

Methods

The study is a retrospective single-center cohort of 571 recipients who underwent living or deceased donor open RTx between 2014 and 2021. Data were collected on background information and perioperative and postoperative data. Complications were defined as short-term (<30 d) or long-term (>30 d) after transplantation and graded according to the Clavien-Dindo classification. Multivariable logistic regression was performed to evaluate risk factors for serious short-term complications and multivariable time-dependent Cox regression to evaluate risk factors for long-term complications.

Results

A total of 351 patients received a graft from a deceased donor, and 144 of these grafts were on perfusion machine before transplantation. One or more short-term complications occurred in 345 (60%) patients. Previous RTx was associated with short-term Clavien-Dindo >2 complications in recipients (odds ratio = 2.08; 95% confidence interval [CI], 1.18-3.69; P = 0.01). Being underweight (body mass index <18.5) in combination with increasing age increased the odds of short-term Clavien-Dindo >2 and vascular complications. Increasing blood loss per 100 mL was associated with increased odds of short-term Clavien-Dindo >2 (odds ratio = 1.11; 95% CI, 1.01-1.21; P = 0.032). No associations were found for long-term complications after RTx. The 5-y cumulative incidence of graft loss was 12.6% (95% CI, 8.9-16.3).

Conclusions

Short-term complications are common after RTx, and risk factors for severe short-term complications include previous RTx, increasing age, and low body mass index. No risk factors were identified for severe long-term complications. Further studies should explore whether new surgical techniques can reduce surgical complications in RTx.

Safety and utility of panniculectomy in renal transplant candidates and end stage renal disease patients

BACKGROUND

As the obesity crisis in the United States continues, some renal transplantation centers have liberalized their BMI criteria necessary for transplant eligibility. More individuals with larger body-habitus related comorbidities with End-Stage Renal Disease (ESRD) now qualify for renal transplantation (RT). Surgical modalities from other fields also interact with this patient population.

METHODS

In order to assess surgical outcomes of panniculectomy in the context of renal transplantation and ESRD, the authors performed a systematic review following the Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) 2020 guidelines. Due to a paucity of existing primary studies, we retrospectively collected data on patients with ESRD undergoing panniculectomy from the American College of Surgeons' National Surgical Quality Improvement Program (NSQIP) to evaluate outcomes of body contouring in this patient population.

RESULTS

From the systematic review, a total of 783 ESRD patients underwent panniculectomy among the studies identified. Of these, 91 patients underwent panniculectomy simultaneously to RT while 692 had their pannus resected prior to kidney transplant. The most common complication was hematoma followed by wound dehiscence. From the NSQIP database, 24 868 patients met the inclusion criteria for analysis. In the setting of renal transplant status, patients with diabetes, hypertension requiring medication, and requiring dialysis were more likely to suffer postoperative complications (OR 1.31, 1.15, and 2.2, respectively). However, upon sub-analysis of specific types of complications, the only retained association was between diabetes and wound complication.

CONCLUSION

Preliminary data show that panniculectomy in ESRD patients appears to be safe, though with a nominal increased risk for complications. Pannus resection does not appear to impact post-transplantation outcomes, including long-term allograft survival. Larger, higher powered, randomized studies are needed to confirm the safety, utility, and medical benefit of panniculectomy in the context of renal transplantation.

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

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

Comparison of Kidney Transplantation Outcomes Between Patients with and Without Pre-transplantation Bariatric Surgery: a Systematic Review

This systematic review evaluated the impact of bariatric surgery, performed to improve eligibility for kidney transplantation, on post-transplantation outcomes. A systematic literature search was performed for articles published by 30 January 2022. A total of 31 studies were included. Among patients without pre-transplantation bariatric surgery, 18 studies reported 13.7% graft loss and 9.1% mortality within 5 years' post-transplantation. Among recipients with pre-transplantation bariatric surgery, 15 studies reported 8.7% graft loss and 2.8% mortality within 1 month to over 5 years' post-transplantation. Two case-control studies comparing post-transplantation outcomes between recipients with and without prior bariatric surgery demonstrated no significant differences between groups for graft loss, patient mortality, delayed graft function, wound complications and lymphocele. Non-randomized selection of patients and different lengths of follow-up limit the results of this study.

Distinct Phenotypes of Kidney Transplant Recipients in the United States with Limited Functional Status as Identified through Machine Learning Consensus Clustering

Background: There have been concerns regarding increased perioperative mortality, length of hospital stay, and rates of graft loss in kidney transplant recipients with functional limitations. The application of machine learning consensus clustering approach may provide a novel understanding of unique phenotypes of functionally limited kidney transplant recipients with distinct outcomes in order to identify strategies to improve outcomes. Methods: Consensus cluster analysis was performed based on recipient-, donor-, and transplant-related characteristics in 3205 functionally limited kidney transplant recipients (Karnofsky Performance Scale (KPS) < 40% at transplant) in the OPTN/UNOS database from 2010 to 2019. Each cluster’s key characteristics were identified using the standardized mean difference. Posttransplant outcomes, including death-censored graft failure, patient death, and acute allograft rejection were compared among the clusters Results: Consensus cluster analysis identified two distinct clusters that best represented the clinical characteristics of kidney transplant recipients with limited functional status prior to transplant. Cluster 1 patients were older in age and were more likely to receive deceased donor kidney transplant with a higher number of HLA mismatches. In contrast, cluster 2 patients were younger, had shorter dialysis duration, were more likely to be retransplants, and were more likely to receive living donor kidney transplants from HLA mismatched donors. As such, cluster 2 recipients had a higher PRA, less cold ischemia time, and lower proportion of machine-perfused kidneys. Despite having a low KPS, 5-year patient survival was 79.1 and 83.9% for clusters 1 and 2; 5-year death-censored graft survival was 86.9 and 91.9%. Cluster 1 had lower death-censored graft survival and patient survival but higher acute rejection, compared to cluster 2. Conclusion: Our study used an unsupervised machine learning approach to characterize kidney transplant recipients with limited functional status into two clinically distinct clusters with differing posttransplant outcomes.

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.

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.

Outcomes of first versus third kidney transplantations: propensity score matching and paired subgroup analysis-a single-centre experience

Background

In the Eurotransplant, 12.6% of kidney transplantations are a repeat procedure. Third transplants are significantly more complex than first and second ones. We compared the results of first (PRT) versus third (TRT) transplantations.

Methods

Between 2011 and 2016, we performed 779 deceased donor adult kidney transplantations, 14.2% out of them were second, 2.6% (20) third, and 0.3% fourth. We compared the pre-, intra-, and postoperative data, kidney function, and survival rate.

Results

Recipients of TRT were younger (53.4 vs. 47.3 p = 0.02). HCV infection rate (20%, p = 0.00) is ten times higher. The operation time is longer (132 vs. 152 min, p = 0.02), and delayed graft function is much more frequent (22.4% vs. 60%, p = 0.00). Induction therapy was given to every TRT (7.9% vs.100%), but as a result, the rejection rate was the same (~ 15%). Hospital stay is a week longer. Patient’s survival at 1, 3, and 5 years for PRT is 96.4%, 93.9%, and 91.2% and for TRT is 90%, 85%, and 78.4%, respectively (p = 0.023). TRT’s odds ratio of fatal outcome is 4.35 (1.5–12.5). Graft survival at 1, 3, and 5 years for PRT is 93.1%, 91.4%, and 90.3% and for TRT is 75%, 75%, and 75%, respectively (p = 0.020). TRT’s odds ratio of graft loss is 3.14 (1.1–8.9). Of PRT 85.76%, out of PRT 85.76%, while out of TRT 60% live with a functioning graft, p=0.00149.

Conclusion

In a third transplant, both graft and patient survival are significantly inferior to primer ones. Careful selection is required to minimize the patient risk and graft loss.

Obesity in the Kidney Transplant Process

Obesity, which has become an increasing problem worldwide, poses a risk for kidney transplant recipients both before and after surgery. In this literature review, we studied the effects of obesity before and after kidney transplant. There are numerous studies and different opinions on the effects of obesity on graft function before and after transplant. Obesity prolongs surgery time and the ischemic process. A large cohort study of 11 836 recipients noted a close association between body mass index and delayed renal transplant and delayed graft function. However, another study found that being overweight or obese before transplant did not have any effects over the medium and long term. A 20-year follow-up study indicated that the firstyear body mass index in recipients after renal transplant had a greater effect on graft function and survival than body mass index before transplant. Still, another study found that body mass index had no effects on graft function and survival. In the study, 3-year graft function and mortality rates of morbidly obese people without diabetes, the functional status without dialysis, and living-donor transplant were reported to be much lower than in those with normal weight. In conclusion, there is no consensus on the effects of obesity before and after transplant, and it has been pointed out that more research should be done on this subject.