Clinical impact of abdominal fat distribution measured by 3-D computed tomography volumetry on post-transplant renal function in recipients after living kidney transplantation: a retrospective study

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

Ameliorating Metabolic Profiles After Kidney Transplantation: A Protocol for an Open-Label, Prospective, Randomized, 3-Arm, Controlled Trial

Aim: High prevalence of metabolic disorders causes higher risk of cardiovascular diseases after kidney transplantation (KT), which remains the main burden impairing short-term and long-term survival. This open-label, prospective, randomized, 3-arm, controlled trial will evaluate the safety, tolerability and efficacy of metformin and empagliflozin in ameliorating metabolic profiles after KT.

Methods: After a screening assessment, eligible patients with an estimated glomerular filtration rate (eGFR) >45 mL/min/1.73m2 are randomly assigned to standard triple immunosuppression alone, standard immunosuppression plus metformin (500 mg twice daily), standard immunosuppression plus empagliflozin (25 mg once daily) from discharge. The primary endpoint is the differences in the visceral-to-subcutaneous fat area ratio over 12 months, evaluated by magnetic resonance imaging (MRI). Secondary outcomes include kidney graft function, glycometabolism, lipid metabolism, and inflammatory parameters. The trial will enroll 105 kidney transplant recipients, providing 90% power to detect the difference at 5% significance.

Pre-transplant morphometry by computed tomography scan and post-transplant dialysis risk in overweight or obese kidney transplant recipients

PURPOSE

Adipose distribution and sarcopenia could better assess kidney transplantation outcomes than body mass index (BMI) and have been poorly evaluated among obese and overweight recipients. We aimed to evaluate morphometric radiologic markers to predict post-operative dialysis within this population.

METHODS

We conducted a retrospective study including patients with a BMI > 25 kg/m² undergoing kidney transplantation during 5 years. Subcutaneous adipose tissue surface (SAT), visceral adipose tissue surface (VAT), and psoas surface were measured on CT scans sections. A model predictive of post-transplantation dialysis was elaborated through a multivariable logistic regression and was compared to a model including only BMI.

RESULTS

Overall, 248 patients were included whom mean (SD) BMI and age were, respectively, 29.7 kg/m2 (3.6) and 56 years (12.7). Of them, 83 (33.5%) needed dialysis: 14 (5.7%) for primary kidney failure and 69 (27.8%) for delayed kidney function. On multivariable analysis, SAT, VAT and deceased donor were significantly associated with post-operative dialysis (respectively, OR [95%CI]:1.6 [1.1-2.6], 1.6[1.1-2.6], and 7.5 [1.6-56]). The area under the curve of this predictive model was 0.70 versus 0.64 for a BMI-based model.

CONCLUSION

High VAT and SAT were associated with post-transplantation dialysis. A predictive model based on these morphometrics could provide a better appreciation of graft recovery after transplantation among obese and overweight recipients. External validation is needed.

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.

Latest developments in living kidney donation

PURPOSE OF REVIEW

Although the first successful kidney transplantation 65 years ago was performed with a living donor kidney, the number of living donor kidney transplantations has increased especially during the last 2 decades. The enlargement of living donor programs was made possible by new modes of living donation and by expansion of the living donor pool. At the same time, the long-term risks of kidney donation have been better delineated. In this review, the latest developments on these topics are summarized.

RECENT FINDINGS

While the results of ABO-incompatible living kidney transplantation are superior to those of deceased donor transplantation, recent meta-analyses show a reduced patient and graft survival as compared with ABO compatible transplantation as well as increased risk of severe infection and bleeding. Kidney paired donation programs can be extended by including compatible couples and by advanced donation, although the latter raises ethical concerns. Living donors appear to have a higher risk of end-stage renal disease and this is especially true for obese donors and probably also for black donors with an APOL1 high-risk genotype. The importance of psychosocial outcomes after living kidney donation is increasingly recognized.

SUMMARY

Living donor kidney transplantation remains the optimal treatment option for patients with end-stage renal disease. To increase the donor pool, a well developed paired kidney donation program and sufficient reimbursement of costs associated with donation are essential ingredients. Other ways of expanding the donor pool, such as ABO-incompatible transplantation, use of higher risk donors, providing donors with financial incentives and advanced donation are associated with medical, ethical and logistical complications. There should be a careful selection and follow-up of living kidney donors with attention for medical consequences as well as for psychosocial outcomes.

Temporary contraindication of obese recipients in kidney transplantation: A new morphometric tool for decision support

BACKGROUND

Morbid obesity, based on body mass index (BMI) and/or clinical examination, can be a temporary contraindication (TCI) of kidney transplantation. However, BMI alone does not evaluate the intra- or extra-peritoneal distribution of fatty tissue, and clinical examination alone is subjective. The objective was to evaluate the interest of morphometric criteria to ensure reproducible and consensual decision of TCI.

METHODS

We retrospectively included patients with a BMI >30 transplanted or temporarily contraindicated because of their weight from 2012 to 2017. The following measurements were performed on CT scan sections using a semiautomatic Hounsfield density detection software: subcutaneous adipose tissue surface (SAT), visceral adipose tissue surface (VAT), vessel-to-skin distance (VSK), abdominal perimeter (AP), and psoas index. Performance of morphometric measures to predict TCI was assessed through ROC analysis.

RESULTS

Ninety-seven patients were included: 76 kidney transplant recipients and 21 on the TCI list. The area under the curve (AUC, 95%CI) for the BMI model to predict TCI was 0.81 (0.72-0.90). A 5-variable model including BMI, VAT, VSK, AP, and age gave an AUC of 0.88 (0.78-0.98).

CONCLUSIONS

Morphometric obesity parameters are associated with TCI decision-making for kidney transplantation: When combined with BMI in a "morphometric tool," they were predictive of a TCI decision.

A High Visceral-To-Subcutaneous Fat Ratio is an Independent Predictor of Surgical Site Infection after Gastrectomy

Recent studies have shown that body composition is an important factor that affects surgical site infection (SSI). However, each study has utilized different body composition criteria. Therefore, in this study, we aim to determine the most predictable body composition criteria for the prediction of SSI after gastrectomy. The visceral fat area (VFA), subcutaneous fat area (SFA), and muscle area were assessed by a preoperative-stage computed tomographic (CT) scan. To compare the predictive performance of body composition for SSI, logistic regression models were used, and the models were compared using the receiver operation characteristic (ROC) curve and the area under the curve (AUC) value. Of the 1038 eligible patients, 58 patients (5.6%) developed SSI. The VFA-to-SFA ratio showed the best predictive performance (mean AUC 75.11). The cutoff value for the SSI of the VFA-to-SFA ratio was 0.94, and the sensitivity and specificity were 67.86% and 77.65%, respectively. A multivariate logistic analysis indicated that a total gastrectomy (OR, 2.13; p = 0.017), stage III or IV cancer (OR, 2.66; p = 0.003), and a high VFA-to-SFA ratio (OR, 8.09; p < 0.001) were independent risk factors for SSI after gastrectomy. The VFA-to-SFA ratio is the most predictable body composition model for use in predicting the incidence of SSI after gastrectomy.