Body mass index: short- and long-term impact on kidney transplantation

A novel risk score for predicting prolonged length of stay following pediatric kidney transplant

BACKGROUND

Kidney transplants (KT) are accepted as the kidney replacement therapy of choice for children with kidney failure. The surgery itself may be more difficult especially in small children, and often leads to significant hospital stays. There is little research on predicting prolonged length of stay (LOS) in children. We aim to examine the factors associated with prolonged LOS following pediatric KT to help clinicians make informed decisions, better counsel families, and potentially reduce preventable causes of prolonged stay.

METHODS

We retrospectively analyzed the United Network for Organ Sharing database for all KT recipients less than 18 years old between January 2014 and July 2022 (n = 3693). Donor and recipient factors were tested in univariate and multivariate logistic analysis using stepwise elimination of non-significant factors to create a final regression model predicting LOS longer than 14 days. Values were assigned to significant factors to create risk scores for each individual patient.

RESULTS

In the final model, only primary diagnosis of focal segmental glomerulosclerosis, dialysis prior to KT, geographic region, and recipient weight prior to KT were significant predictors of LOS longer than 14 days. The C-statistic of the model is 0.7308. The C-statistic of the risk score is 0.7221.

CONCLUSIONS

Knowledge of the risk factors affecting prolonged LOS following pediatric KT can help identify patients at risk of increased resource use and potential hospital-acquired complications. Using our index, we identified some of these specific risk factors and created a risk score that can stratify pediatric recipients into low, medium, or high risk groups. A higher resolution version of the Graphical abstract is available as Supplementary information.

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.

Impact of robotic-assisted kidney transplantation on post-transplant infections: a case-control study

BACKGROUND

The aim of this study was to determine the differences in the incidence, epidemiology, clinical characteristics and risk factors of infections in living donor kidney transplant recipients using robotic-assisted kidney transplantation (RAKT) and open approach.

METHODS

We conducted a retrospective observational study from January 2016 to December 2019. For the risk factor analysis, a matched case-control study (1:1 ratio) was performed (robotic vs open). Control subjects were matched for living donor and time of transplantation. The data included de novo immunosuppressive regimen, delayed graft function, urological complications, acute allograft rejection and incidence, clinical features, microbiological findings and outcomes of infections.

RESULTS

Ninety-four RAKT and 84 controls were included. There were no differences between groups in terms of age, gender, BMI, median days of hospitalization, immunosuppressive regimen, need for surgical urologic procedures post-transplantation, presence of urinary leak or acute allograft rejection. Thirty-five percent of all recipients analyzed presented an infection, mostly asymptomatic bacteriuria (49%), symptomatic urinary tract infection (31%) and surgical site infection (10%). Pseudomonas aeruginosa was the most frequent isolated microorganism in 67%, followed by E. coli (20%), Enterococcus faecalis (17%) and Klebsiella pneumoniae (10%). Eight percent of the microorganisms were multidrug resistant. The open kidney transplantation group presented more infections compared to RAKT (43 vs 27%, p = 0.04). After multivariate analysis, need for surgical urologic procedure post-transplantation (OR 6.2, 95% CI 1.1-35), BMI ≥ 30 (OR 3.6, 95% CI 1.5-9) and acute allograft rejection (OR 3.2, 95% CI 1.2-8.5) were associated with infection, whereas RAKT (OR 0.5, 95% CI 0.2-0.9) and the use of JJ catheter (OR 0.36, 95% CI 0.17-0.72) were protective factors.

CONCLUSIONS

Infection is a frequent event in patients receiving a living donor kidney transplant. Acute allograft rejection, need for surgical urologic procedure post-transplantation and BMI were associated with infection, whereas robotic surgery was a protective factor in living donor kidney transplantation.

Factors Influencing Lymphocele Development After Kidney Transplant: Single Center Experience

OBJECTIVES

Lymphocele is a well-known postoperative surgical complication after kidney transplant. In this study, our aim was to analyze incidence, risk factors, and outcomes of posttransplant lymphocele in a large cohort.

MATERIALS AND METHODS

This observational study included 395 consecutive patients (219 males and 176 females) who underwent kidney transplant procedures from 183 living and 212 deceased donors in our center between January 2007 and 2014. A lymphocele was diagnosed with ultrasonography.

RESULTS

The incidence of lymphoceles in our cohort was 31.9% (n = 126). There were no significant dif-ferences with regard to body mass indexes, age of donors, deceased donor ratios, acute rejection episodes, and history of abdominal surgery between those with and without lymphoceles. The pre-transplant serum albumin levels (3.29 ± 0.67 vs 3.48 ± 0.69 g/dL; P = .009) in the lymphocele group and diabetes mellitus ratios (15.9% vs 4.5%; P < .001) in the nonlymphocele group were lower than levels shown in the other group. The lymphocele ratio in patients who received cyclosporine was higher than that shown in patients who did not received it (37.5% vs. 27.4%; P = .032). There was no difference in lymphocele incidence between patients who were taking and those who were not taking mammalian target of rapamycin inhibitors, mycophenolate mofetil, or mycophenolate sodium. In regression analysis, presence of diabetes mellitus, transplant from deceased donors, older age of donors, and lower albumin levels were independent risk factors for posttransplant lymphocele occurrence.

CONCLUSIONS

Posttransplant lymphocele was a relatively common surgical complication in our cohort. We concluded that diabetes mellitus, use of kidneys from deceased donors, older donor age, and hypoalbuminemia were independent risk factors for lymphocele development.

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.

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.

Obesity, Chronic Kidney Disease, and Kidney Transplantation: An Evolving Relationship

Obesity has a fundamental role in driving the global kidney disease burden. The perplexing relationship of obesity with chronic kidney disease remains debated. However, a thorough understanding of the interplay of obesity in conjunction with chronic kidney disease and appropriate management options is lacking, leading to further increases in morbidity and mortality. Moreover, underutilization of bariatric procedures and unrealistic expectations of weight reduction based on body mass index, leading to poor access to kidney transplantation, are fueling the fire. In this review, we summarize the available data related to the obesity and chronic kidney disease association and its novel management options.

Robotic kidney transplantation in the obese patient: 10-year experience from a single center

Despite increasing obesity rates in the dialysis population, obese kidney transplant candidates are still denied transplantation by many centers. We performed a single-center retrospective analysis of a robotic-assisted kidney transplant (RAKT) cohort from January 2009 to December 2018. A total of 239 patients were included in this analysis. The median BMI was 41.4 kg/m² , with the majority (53.1%) of patients being African American and 69.4% of organs sourced from living donors. The median surgery duration and warm ischemia times were 4.8 hours and 45 minutes respectively. Wound complications (mostly seromas and hematomas) occurred in 3.8% of patients, with 1 patient developing a surgical site infection (SSI). Seventeen (7.1%) graft failures, mostly due to acute rejection, were reported during follow-up. Patient survival was 98% and 95%, whereas graft survival was 98% and 93%, at 1 and 3 years respectively. Similar survival statistics were obtained from patients undergoing open transplant over the same time period from the UNOS database. In conclusion, RAKT can be safely performed in obese patients with minimal SSI risk, excellent graft function, and patient outcomes comparable to national data. RAKT could improve access to kidney transplantation in obese patients due to the low surgical complication rate.

Abdominal wall complications following renal transplantation in adult recipients - factors associated with interventional management in one unit

Background

Abdominal wall surgical site complications following renal transplantation can be challenging to manage. A sub-group of these recipients will require operative management or advanced wound care such as negative pressure wound therapy (NPWT). The aim of this study was to determine if there were any preoperative, intraoperative and postoperative characteristics in our recipients’ cohort which were associated with the requirement for such interventions.

Methods

A retrospective review of medical records was performed for all recipients who sustained abdominal wall complications following renal transplantation at our centre from 2006 to 2016.

Results

A total of 64/828 recipients (7.7%) had abdominal wall complications. The mean weight for these patients was 84.9 kg (±16.6 kg) and the mean body mass index was 30.2 (±5.1). Forty-five recipients (70%) had a superficial wound dehiscence while nine (14%) had a complete fascial dehiscence. Operative intervention was required in 13/64 patients (20%) and was more likely to be required in the presence of a fascial dehiscence (9/9, 100%) or a wound collection (10/31, 32%) (p < 0.001, p = 0.021). NPWT was used in 17/64 patients (27%) and was more commonly required in patients with diabetes mellitus (10/24, 42%), a complete fascial dehiscence (5/9, 56%) or evidence of infection (16/44, 36%) (p = 0.039, p = 0.034, p = 0.008).

Conclusions

The requirement for either operative management or the use of NPWT in the management of abdominal wall complications following renal transplantation in our experience was more common in recipients with diabetes mellitus, and in the setting of either complete fascial dehiscence, abdominal wall wound collections and/ or infection.

Development of a Novel Prognostic Risk Score for Predicting Complications of Penectomy in the Surgical Management of Penile Cancer

INTRODUCTION

Penectomy for PC is useful in staging, disease prognosis, and treatment. Limited studies have evaluated its surgical complications. We sought to assess these complications and determine predictive models to create a novel risk score for penectomy complications.

PATIENTS AND METHODS

A retrospective review of patients undergoing PC surgical management from the 2005-2016 American College of Surgeons National Surgical Quality Improvement Program was performed. Data were queried for partial and total penectomy among those with PC. To develop predictive models of complications, we fit LASSO logistic, random forest, and stepwise logistic models to training data using cross-validation, demographic, comorbidity, laboratory, and wound characteristics as candidate predictors. Each model was evaluated on the test data using receiver operating characteristic curves. A novel risk score was created by rounding coefficients from the LASSO logistic model.

RESULTS

A total of 304 cases met the inclusion criteria. Overall incidence of penectomy complications was 19.7%, where urinary tract infection (3.0%), superficial surgical site infection (3.0%), and bleeding requiring transfusion (3.9%) were most common. LASSO logistic, random forest, and stepwise logistic models for predicting complications had area under the curve (AUC) [95% confidence interval] values of 0.66 [0.52-0.81], 0.73 [0.63-0.83], and 0.59 [0.45-0.74], respectively. Eleven variables were included in the risk score. The LASSO model-derived risk score had moderately good performance (area under the curve [95% confidence interval] 0.74 [0.66-0.82]). Using a cutoff point of 6, the score attains sensitivity 0.58, specificity 0.74, and kappa 0.26.

CONCLUSION

PC management through penectomy is associated with appreciable complications rates. Predictive models of penectomy complications performed moderately well. Our novel prognostic risk score may allow for improved preoperative counseling and risk stratification of men undergoing surgical management of PC.

Obesity and its implications on nononcological urological surgery

PURPOSE OF REVIEW

To review and summarize the current literature of the implications of obesity on nononcological urological surgery. We conducted a comprehensive search of the current literature with emphasis on the published literature in the last 18 months.

RECENT FINDINGS

Over time, obese patients have become a more common encounter in clinical practice. Obesity represents a considerable operative challenge and has been linked to a higher rate of postoperative complications. Data regarding surgery for incontinence are inconsistent. Nevertheless, the success rates in obese women are high, and complication rates are relatively low with comparable results to nonobese women. In renal surgery, percutaneous nephrolithotomy and minipercutaneous nephrolithotomy are feasible, well tolerated, and effective even in obese patients. However, certain precautions and availability of proper instruments are necessary.

SUMMARY

Although randomized clinical data are lacking and the results of many studies are inconsistent, evidence supports the feasibility and safety of different nononcological urological interventions in obese patients. Moreover, the success rates and the overall complication rates seem to be comparable to nonobese patients with some exceptions.

The Diet and Haemodialysis Dyad: Three Eras, Four Open Questions and Four Paradoxes. A Narrative Review, Towards a Personalized, Patient-Centered Approach

The history of dialysis and diet can be viewed as a series of battles waged against potential threats to patients' lives. In the early years of dialysis, potassium was identified as "the killer", and the lists patients were given of forbidden foods included most plant-derived nourishment. As soon as dialysis became more efficient and survival increased, hyperphosphatemia, was identified as the enemy, generating an even longer list of banned aliments. Conversely, the "third era" finds us combating protein-energy wasting. This review discusses four questions and four paradoxes, regarding the diet-dialysis dyad: are the "magic numbers" of nutritional requirements (calories: 30-35 kcal/kg; proteins > 1.2 g/kg) still valid? Are the guidelines based on the metabolic needs of patients on "conventional" thrice-weekly bicarbonate dialysis applicable to different dialysis schedules, including daily dialysis or haemodiafiltration? The quantity of phosphate and potassium contained in processed and preserved foods may be significantly different from those in untreated foods: what are we eating? Is malnutrition one condition or a combination of conditions? The paradoxes: obesity is associated with higher survival in dialysis, losing weight is associated with mortality, but high BMI is a contraindication for kidney transplantation; it is difficult to limit phosphate intake when a patient is on a high-protein diet, such as the ones usually prescribed on dialysis; low serum albumin is associated with low dialysis efficiency and reduced survival, but on haemodiafiltration, high efficiency is coupled with albumin losses; banning plant derived food may limit consumption of "vascular healthy" food in a vulnerable population. Tailored approaches and agreed practices are needed so that we can identify attainable goals and pursue them in our fragile haemodialysis populations.