Renal transplantation in children younger than 6 years old

Pediatric kidney transplantation: outcomes with under and over 6-year-old donors

OBJECTIVE

Kidney shortage for pediatric kidney transplantation (PKT) entails the need to use low-weight and age donors, despite the apprehension. The aim of this study was to analyze the pediatric deceased donor kidney transplantations (pDDKT) outcomes in the first year after the procedure, stratified by donor age.

METHOD

Retrospective cohort of pDDKTs carried out between January 2013, and January 2018, at a PKT reference hospital in Southern Brazil. Donors were divided into group 1 (≤ 6 years), and group 2 (> 6 years); the analysis of the outcomes was carried out in the same period.

RESULTS

There were 143 pDDKTs; 51 (35.66%) in group 1; and 92 (64.34%) in group 2. In both groups there were 17 graft losses (11.8%), with vascular thrombosis as the main cause (group 1: 5; group 2: 4). Among the complications, renal artery stenosis (RAS) with indication for angioplasty and stenting was more frequent in group 1 (7.8%; group 2: 2.2%). The 1-year Renal Transplant Recipients' and graft survival did not show significant differences between the groups, (p =  = 0.95). However, the Glomerular Filtration Rate analysis was higher in group 2, reaching, in the 12th month, 79.3 mL/min/1,73m2, compared to 69.7 mL/min/1,73m2 in group 1(p =  = 0.033).

CONCLUSIONS

Small donors can be considered for pDDKTs, as long as there is an expert team to perform the transplantation.

Assessment of prophylactic heparin infusion as a safe preventative measure for thrombotic complications in pediatric kidney transplant recipients weighing <20 kg

Small-sized kidney recipients (<20 kg) are at high risk of allograft vessel thrombosis. HP has been used to mitigate this risk but may infer an increase in bleeding risks. Therefore, we aim to determine whether HP is a safe means to prevent thrombosis in small kidney transplant patients by comparing those who have received HP and those who have NHP. A retrospective review of patients < 20 kg who underwent kidney transplant in our institution from 2000 to 2015 was performed. At our institution, unfractionated heparin 10 units/kg/hour is used as HP since 2009. Patients at increased risk of thrombosis (previous thrombosis, thrombophilia, nephrotic syndrome) and bleeding (therapeutic doses of heparin, diagnosis of coagulopathy) were excluded. Fifty-six patients were identified (HP n = 46; NHP n = 10). Baseline demographics were similar between HP and NHP. There was no statistical difference in frequency of transfusions, surgical re-exploration, or thrombotic events between HP and NHP. The HP group was more likely to have drop in Hb > 20 g/L (67.4% vs 30.0%, P = 0.038), and those who had drop in Hb > 20 g/L were more likely to also require pRBC transfusions (63.0% vs 20.0%, P = 0.017). Within the HP group, those who had bleeding complications had similar Hb levels as those who did not at baseline and post-transplant. Outcomes in the HP and NHP groups were no different with respect to thrombosis or significant bleeding complications requiring pRBC transfusions or surgical intervention. Future prospective studies are required to investigate the balance of preventing thrombosis and risks of pRBC transfusions for small-sized kidney recipients.

Perioperative antithrombotic therapy does not increase the incidence of early postoperative thromboembolic complications and bleeding in kidney transplantation - a retrospective study

Perioperative antithrombotic therapy could play a role in preventing thromboembolic complications (TEC) after kidney transplantation (KTx), but little is known on postoperative bleeding risks. This retrospective analysis comprises 2000 single‐organ KTx recipients transplanted between 2011 and 2016 in the two largest transplant centers of the Netherlands. TEC and bleeding events were scored ≤7 days post‐KTx. Primary analyses were for associations of antithrombotic therapy with incidence of TEC and bleeding. Secondary analyses were for associations of other potential risk factors. Mean age was 55 ± 14 years, 59% was male and 60% received a living donor kidney. Twenty‐one patients (1.1%) had a TEC. Multiple donor arteries [OR 2.79 (1.15–6.79)] and obesity [OR 2.85 (1.19–6.82)] were identified as potential risk factors for TEC. Bleeding occurred in 88 patients (4.4%) and incidence varied significantly between different antithrombotic therapies (P = 0.006). Cardiovascular disease [OR 2.01 (1.18–3.42)], pre‐emptive KTx [OR 2.23 (1.28–3.89)], postoperative heparin infusion [OR 1.69 (1.00–2.85)], and vitamin K antagonists [OR 6.60 (2.95–14.77)] were associated with an increased bleeding risk. Intraoperative heparin and antiplatelet therapy were not associated with increased bleeding risk. These regimens appear to be safe for the possible prevention of TEC without increasing the risk for bleeding after KTx.

Preemptively and non-preemptively transplanted patients show a comparable hypercoagulable state prior to kidney transplantation compared to living kidney donors

To prevent renal graft thrombosis in kidney transplantation, centres use different perioperative anticoagulant strategies, based on various risk factors. In our centre, patients transplanted preemptively are considered at increased risk of renal graft thrombosis compared to patients who are dialysis-dependent at time of transplantation. Therefore these patients are given a single dose of 5000 IU unfractionated heparin intraoperatively before clamping of the vessels. We questioned whether there is a difference in haemostatic state between preemptively and non-preemptively transplanted patients and whether the distinction in intraoperative heparin administration used in our center is justified. For this analysis, citrate samples of patients participating in the VAPOR-1 trial were used and several haemostatic and fibrinolytic parameters were measured in 29 preemptively and 28 non-preemptively transplanted patients and compared to 37 living kidney donors. Sample points were: induction anaesthesia (T1), 5 minutes after reperfusion (T2) and 2 hours postoperative (T3). At T1, recipient groups showed comparable elevated levels of platelet factor 4 (PF4, indicating platelet activation), prothrombin fragment F1+2 and D-dimer (indicating coagulation activation) and Von Willebrand Factor (indicating endothelial activation) compared to the donors. The Clot Lysis Time (CLT, a measure of fibrinolytic potential) was prolonged in both recipient groups compared to the donors. At T3, F1+2, PF4 and CLT were higher in non-preemptively transplanted recipients compared to preemptively transplanted recipients. Compared to donors, non-preemptive recipients showed a prolonged CLT, but comparable levels of PF4 and D-dimer. In conclusion pre-transplantation, preemptively and non-preemptively transplanted patients show a comparable enhanced haemostatic state. A distinction in intraoperative heparin administration between preemptive and non-preemptive transplantation does not seem justified.

Renal transplantation in children under 3 years of age: Experience from a single-center study

RTx remains challenging in children under 3 years of age. This single-center study reviewed the medical records of children <3 years transplanted since 1987 (N = 32, Group 1). They were matched for donor type and RTx period with children aged 3-13 years (N = 32, Group 2) and 13-18 years (N = 32, Group 3). There were no between-group significant differences regarding distributions of gender, primary renal disease, proportion of dialysis before RTx, and growth (SDS). Compared to Groups 2 and 3, Group 1 had more peritoneal dialyses (P < .001), more EBV mismatches (P = .04), and longer warm ischemia times (P < .001). The risk of graft loss was not significantly different among age groups (hazard ratio, 2.4 in Group 2 and 2.0 in Group 3 vs Group 1; P = .2). Death occurred in four patients (3 in Group 1 and 1 in Group 2) and graft loss occurred in 28 patients, mainly due to chronic allograft nephropathy. In recipients <3 years of age, the outcomes of RTx are close to those obtained in older pediatric age groups. Thus, young patients may be transplanted in experienced multidisciplinary teams without additional risks provided that particular attention is paid to donor selection and prevention/early diagnosis of comorbidities and complications.

[Etiologies of end-stage renal disease of children in Tunisia]

BACKGROUND

The end-stage renal disease (ESRD) in children has special features in terms of etiologies, therapeutic modalities and access to renal transplantation. In Tunisia, there are no data on the epidemiology of ESRD in children. The aim of our study was to describe epidemiology of ESRD among Tunisian children.

METHODS

This retrospective study was conducted in pediatric departments in Charles-Nicolle Hospital, Tunis and Hedi Chaker hospital, Sfax, during a period of 15 years (1st January 1998-31st December 2013). We included children who develop ESRD before the age of 15 years.

RESULTS

In total, 166 patients were included. The median duration of follow-up was 48 months. We collected respectively 24 children (14.5%) aged less than 2 years, 24 children (14.5%) aged between 2 and 6 years and 118 children (71%) older than 6 years. The sex ratio was equal to 1.4. The mean incidence was 4.25 cases per million children. The main causes were represented by congenital anomalies of the kidneys and urinary tract (35.5%), hereditary renal disease (31.3%) and glomerular kidney disease (9.6%). All patients were treated in kidney transplant dialysis programs; the main mode of dialysis was represented by peritoneal dialysis, which represented the initial dialysis mode in 81% of cases. The transition to hemodialysis was noted in 43.4% cases. Thirty-eight patients (22.8%) were transplanted. The mortality rate was 27.1%. The leading cause of death was cardiovascular diseases (37.7%) and infections (22.2%).

CONCLUSION

The creation of a national registry of kidney disease in Tunisia is necessary for a better knowledge of needs for dialysis and renal transplantation in children.

Renal transplantation in children with nephrotic syndrome in the first year of life

OBJECTIVE

The aim of this work was to analyze the evolution of the 1st renal transplantation in children with nephrotic syndrome in the 1st year of life (NSFL).

METHODS

In this retrospective study of 15 patients (8 women and 7 men) with NSFL receiving transplants from 1989 to 2013, 9 had NS of Finnish type, 4 diffuse mesangial sclerosis, 1 minimal changes, and 1 collapsing glomerulopathy. We analyzed the clinical and analytic situation at 4 time points: before dialysis, before transplantation, 3 months after transplantation, and long-term evolution.

RESULTS

Mean follow-up was 72.8 months (range, 1 month to 16.9 years); mean age at diagnosis was 2.21 months (range, 0-8.2 months); mean age at onset of replacement therapy was 22.9 ± 16.4 months (range, 3.8-55.4 months); and mean time on dialysis was 14.9 months (range, 2-44 months). Age at transplantation was 3.1 years (range, 1.8 to 7.7 years), with 6 living-donor transplantations (LDTs) and 9 cadaveric (CDTs). Ten patients required nephrectomy before transplantation (9 bilateral) to control proteinuria after 3.1 ± 3.8 months on dialysis, 1 during transplantation, and 3 after transplantation (2 persistent proteinuria, 1 hypertension). Mean time on dialysis for LDTs was 5.4 ± 2.7 months versus 13.2 ± 6.9 months for CDTs (P < .005). Mean age of cadaveric donors was 6.2 ± 2.4 years and that of living donors 35.5 ± 7.9 years. As complications, there was 1 bleeding from venous anastomosis and 1 urinary leakage after surgery. After 6 ± 5.2 years of evolution, actuarial survival at both 1 and 7 years was 92.9%. One graft was lost owing to acute rejection 1 month after transplantation and 2 others owing to chronic rejection >9 years after transplantation. None had disease recurrence.

CONCLUSIONS

Short-term complications did not differ from the rest of population if transplantation occurred with standard albumin levels, for which most required pre-transplantation nephrectomy because dialysis failed to reduce proteinuria.

Surgical complications and graft function following live-donor extraperitoneal renal transplantation in children 20 kg or less

OBJECTIVES

To evaluate the effect of patient, surgical, and medical factors on surgical complications and graft function following renal transplantation (Tx) in children weighing ≤ 20 kg, because the number of this challenging group of children is increasing.

PATIENTS AND METHODS

Between June 2009 and October 2013, 26 patients received living donor renal allotransplant using the extraperitoneal approach (EPA). The immunosuppression regimen was composed of prednisolone, mycophenolate mofetil, and ciclosporin or tacrolimus.

RESULTS

The mean weight was 16.46 ± 2.61 kg. Mean cold ischemia time was 53.85 ± 12.35 min. The graft survival rate (GSR) and patient survival rate (PSR) were 96% at 3 years. Acute rejection episodes (AREs) occurred in eight patients (30%). Postoperative surgical complications were ureteral leakage (3), vesicoureteric reflux (2), and renal vein thrombosis (2) (with one graft nephrectomy). Mean follow-up was 37.5 ± 7.4 months.

CONCLUSION

Excellent PSR and GSR can be achieved in low weight (<20 kg) recipients. Even in very low weight patients, the EPA was used. No cases were reported with primary graft non-function due to use of living donors, increasing pre-Tx body weight to at least 10 kg and maintaining adequate filling pressure before graft reperfusion. The presence of related donors and use of induction therapy and tacrolimus decreased the rate of ARE while the presence of pre-Tx lower urinary tract surgical interventions increased the rate of ureteric complications, but this was statistically insignificant.

Identification of risk factors for vascular thrombosis may reduce early renal graft loss: a review of recent literature

Renal graft survival has improved over the past years, mainly owing to better immunosuppression. Vascular thrombosis, though rare, therefore accounts for up to one third of early graft loss. We assess current literature on transplantation, identify thrombosis risk factors, and discuss means of avoiding thrombotic events and saving thrombosed grafts. The incidence of arterial thrombosis was reported to 0.2–7.5% and venous thrombosis 0.1–8.2%, with the highest incidence among children and infants, and the lowest in living donor reports. The most significant risk factors for developing thrombosis were donor-age below 6 or above 60 years, or recipient-age below 5-6 years, per- or postoperative hemodynamic instability, peritoneal dialysis, diabetic nephropathy, a history of thrombosis, deceased donor, or >24 hours cold ischemia. Multiple arteries were not a risk factor, and a right kidney graft was most often reported not to be. Given the thrombosed kidney graft is diagnosed in time, salvage is possible by urgent reoperation and thrombectomy. Despite meticulous attentions to reduce thrombotic risk factors, thrombosis cannot be entirely prevented and means to an early detection of this complication is desirable in order to save the kidneys through prompt reoperation. Microdialysis may be a new tool for this.

Paediatric kidney transplantation in Belgium

In Belgium, kidney transplantation is currently the treatment of choice for a child with end-stage renal disease (ESRD). Dialysis remains the life-saving bridge to transplantation. Within the Eurotransplant (ET) community, Belgium represents 14% of the cadaveric transplantations and 22% of the living-related transplantation (LD) in children less than 16 years of age. Single-centre analysis (KUL) shows a patient survival of 94% at 3 year and 91% at 5 year. The overall graft survival is 82% at 3 year and 74% at 5 year. In the LD group, the graft survival rate is 10% better than the overall actuarial graft survival rate. Multivariate Cox regression analysis performed on all transplantations of one centre (KUL) demonstrate the following factors to be significant and independent predictors of poor graft outcome: absence of calcineurin inhibitors, two HLA- mismatches, duration of pre-transplant dialysis and creatinine clearance at one year after transplantation. The outcome improves by a short dialysis waiting time, the use of living-related donors, the prevention of delayed graft function (DGF), and of acute rejection. Within the ET community, the waiting child has priority compared to the adult, but if we want to avoid morbidity, waiting times must be shortened and the incidence of pre-emptive transplantation, which is currently 24% in Belgium, must increase. The good results with LD is certainly an attractive alternative to be actively encouraged for paediatric kidney recipients and the use of young deceased donors especially for children with ESRD must be supported since the results in terms of graft survival with these donors are very good, especially in children. In paediatric kidney transplantation the long-term graft survival is still the major challenge and has still to be documented by randomized trials. The success of the past, however, allows us to face the future with hope and confidence.