Venous Thromboembolism and the Risk of Death and Graft Loss in Kidney Transplant Recipients

Developing a genetic testing panel for evaluation of morbidities in kidney transplant recipients

Cardiovascular disease, infection, malignancy, and thromboembolism are major causes of morbidity and mortality in kidney transplant recipients (KTR). Prospectively identifying monogenic conditions associated with post-transplant complications may enable personalized management. Therefore, we developed a transplant morbidity panel (355 genes) associated with major post-transplant complications including cardiometabolic disorders, immunodeficiency, malignancy, and thrombophilia. This gene panel was then evaluated using exome sequencing data from 1590 KTR. Additionally, genes associated with monogenic kidney and genitourinary disorders along with American College of Medical Genetics (ACMG) secondary findings v3.2 were annotated. Altogether, diagnostic variants in 37 genes associated with Mendelian kidney and genitourinary disorders were detected in 9.9% (158/1590) of KTR; 25.9% (41/158) had not been clinically diagnosed. Moreover, the transplant morbidity gene panel detected diagnostic variants for 56 monogenic disorders in 9.1% KTRs (144/1590). Cardiovascular disease, malignancy, immunodeficiency, and thrombophilia variants were detected in 5.1% (81), 2.1% (34), 1.8% (29) and 0.2% (3) among 1590 KTRs, respectively. Concordant phenotypes were present in half of these cases. Reviewing implications for transplant care, these genetic findings would have allowed physicians to set specific risk factor targets in 6.3% (9/144), arrange intensive surveillance in 97.2% (140/144), utilize preventive measures in 13.2% (19/144), guide disease-specific therapy in 63.9% (92/144), initiate specialty referral in 90.3% (130/144) and alter immunosuppression in 56.9% (82/144). Thus, beyond diagnostic testing for kidney disorders, sequence annotation identified monogenic disorders associated with common post-transplant complications in 9.1% of KTR, with important clinical implications. Incorporating genetic diagnostics for transplant morbidities would enable personalized management in pre- and post-transplant care.

Short- and long-term outcomes of acute diverticulitis in patients with transplanted kidneys

AIM

The safety of nonoperative treatment for patients with transplanted kidneys who develop acute diverticulitis is unclear. Our primary aim was to examine the long-term sequelae of nonoperative management in this group.

METHOD

We performed a population-based retrospective cohort study using linked administrative databases housed at ICES in Ontario, Canada. We included adult (≥18 years) patients admitted with acute diverticulitis between April 2002 and December 2019. Patients with a functioning kidney transplant were compared with those without a transplant. The primary outcome was failure of conservative management (operation, drainage procedure or death due to acute diverticulitis) beyond 30 days. The cumulative incidence function and a Fine-Grey subdistribution hazard model were used to evaluate this outcome accounting for competing risks.

RESULTS

We examined 165 patients with transplanted kidneys and 74 095 without. Patients with transplanted kidneys were managed conservatively 81% of the time at the index event versus 86% in nontransplant patients. Short-term outcomes were comparable, but cumulative failure of conservative management at 5 years occurred in 5.6% (95% CI 2.3%-11.1%) of patients with transplanted kidneys versus 2.1% (95% CI 2.0%-2.3%) in those without. Readmission for acute diverticulitis was also higher in transplanted patients at 5 years at 16.7% (95% CI 10.1%-24.7%) versus 11.6% (95% CI 11.3%-11.9%). Adjusted analyses showed increased failure of conservative management [subdistribution hazard ratio (sHR) 3.24, 95% CI 1.69-6.22] and readmissions (sHR 1.55, 95% CI 1.02-2.36) for patients with transplanted kidneys.

CONCLUSION

Most patients with transplanted kidneys are managed conservatively for acute diverticulitis. Although long-term readmission and failure of conservative management is higher for this group than the nontransplant population, serious outcomes are infrequent, substantiating the safety of this approach.

Incidence and risk factors of venous thromboembolism in kidney transplantation patients: a prospective cohort study

To investigate the incidence and explore the risk factors of venous thromboembolism (VTE) within 6 months after kidney transplantation. Total of 331 kidney transplant recipients were assessed by venous ultrasonography for VTE at 14 days, 1 month, 3 months, and 6 months post-transplantation. Cox forward regression were used to identify the independent risk factors of VTE. This study registration number is ChiCTR1900020567 and the date of registration was 2019/01/08. The cumulative incidence of VTE was 2.72% (9/331) within 6 months after transplant. 77.8% (7/9) of VTEs occurred in the first 3 months post-transplantation. 88.9% (1/9) of VTEs were asymptomatic, 66.7% (6/9) of VTEs were mural thromboses and in the right lower extremity. Central vena catheterization (HR = 6.94) and severe pulmonary disease (including pneumonia) (HR = 57.35) were the risk factors for VTE in kidney transplantation recipients. KT patients are the high risk population of VTE. Future interventions should be strengthen for KT patients to receive a minimum of 3-month of precautionary measures for VTE, including infection prevention, and strengthening thromboprophylaxis on the CVC or transplanted side of lower extremity.

Prevalence, risk, and outcomes of venous thromboembolic events in kidney transplant recipients: a nested case-control study

INTRODUCTION

Thromboembolism is more common in kidney transplant recipients (KTRs) than in the general population. Studies evaluating arterial and venous thromboembolism (VTE) in KTRs are scarce and the magnitude and risk factors are mostly undefined.

METHODS

A nested control study was conducted from January 1, 2007, to December 31, 2019. Adult KTRs who were detected to have VTE events during this period were included. The primary outcome was to assess the prevalence of VTE in this population. Secondary outcomes were the assessment of the time to occurrence of the thromboembolic events after transplantation and assessing the risk factors and patient survival. For each subject studied, 4 controls were matched from the data set.

RESULTS

Amongst 2158 patients, 97 (4.5%) were found to have VTE. The median follow-up time was 3.9 years (6-156 months). A total of 101 VTE events were recorded. The most common site of VTE was the lower limb deep vein thrombosis in 79 patients (0.03%)).In multivariate Cox regression analysis, serum creatinine of more than 3 mg/dl [HR 1.30, 95% CI (1.03-1.38)] was independently associated with increased VTE risk. Patients who developed a VTE had higher mortality as compared to patients who did not develop VTE. No increased risk of graft failure was found in VTE patients.

CONCLUSION

This study suggests that kidney transplantation surgery is a moderate risk factor for VTE, and VTE is associated with higher morbidity and mortality. However, prospective studies are needed to establish a definite role of VTE in outcomes in KTRs.

Treatment Options for Anemia in Kidney Transplant Patients: A Review

Anemia is common after kidney transplantation. The etiology may be multifactorial, such as causes of anemia in the general population and causes that are unique to the kidney transplant setting. Posttransplant anemia, particularly when severe, may be associated with adverse effects such as graft failure, mortality, and a decline in kidney function. After careful investigation, that is, having excluded or treated reversible causes of anemia, treatment of anemia in patients with a kidney transplant is based on iron supplementation or erythropoiesis-stimulating agents (ESA), although there are no specific guidelines on anemia management in this patient population. Iron therapy is often needed, but optimal and safe iron-deficiency management strategies remain to be defined. Evidence suggests that ESAs are safe and potentially associated with favorable outcomes. Better graft function has been reported with ESA use targeting hemoglobin levels higher than those recommended in the general population with chronic kidney disease and with no apparent increased risk of cardiovascular events. These results require further investigation. Data on the use of hypoxia-inducible factor inhibitors are limited. Prevention and treatment of anemia in kidney transplantation can improve patients' quality of life, life expectancy, allograft function, and survival.

Risk and factors associated with venous thromboembolism following abdominal transplantation

Background

Venous thromboembolism (VTE) remains under-studied among patients undergoing kidney, liver and pancreas (abdominal) transplantation. We characterized the risk and predictors of VTE using a nationally-representative cohort.

Methods

The 2014-2019 Nationwide Readmissions Database was queried to identify all adults undergoing abdominal transplantation. Patients who developed pulmonary embolism or deep venous thrombosis were considered the VTE cohort (others: nonVTE). Multivariable models were developed to identify factors linked with VTE and assess the independent associations between VTE and key outcomes.

Results

Of ~141,977 transplant recipients, 1.9 % (2722) developed VTE. The VTE cohort was similarly female (39.2 vs 38.0, p = 0.51), but more often demonstrated a higher Elixhauser comorbidity index (4.19 ± 1.40 vs 3.93 ± 1.39, p < 0.001).After adjustment, congestive heart failure (AOR 1.54, 95%CI 1.25-1.91), cardiac arrhythmias (AOR 1.54, 95%CI 1.34-1.78), peripheral vascular disease (AOR 1.29, 95%CI 1.02-1.63), coagulopathies (AOR 1.63, 95%CI 1.38-1.92), previous history of VTE (AOR 1.14, 95%CI 1.06-1.22), and heparin-induced thrombocytopenia (AOR 2.61, 95%CI 2.07-3.28) were associated with VTE. The development of VTE was linked with significantly greater in-hospital mortality (AOR 4.56, 95%CI 2.07-10.10), as well as infectious (AOR 2.59, 95%CI 1.55-4.21), cardiac (AOR 2.59, 95%CI 1.39-4.82), and respiratory (AOR 1.78, 95%CI 1.21-2.63) complications. VTE was further associated with increased length of stay (+8.18 days, 95%CI +1.32-15.41), expenditures (+$42,000, 95%CI $24,800-59,210), and odds of VTE upon readmission (AOR 4.51, 95%CI 1.32-15.41).

Conclusions

VTE after abdominal transplantation is linked with significantly greater in-hospital mortality, complications, resource utilization, and risk of VTE at readmission. Novel risk assessments and prophylaxis protocols are needed to reduce VTE incidence and sequelae.

Safety and mortality outcomes for direct oral anticoagulants in renal transplant recipients

PURPOSE

Direct oral anticoagulants (DOACs) are increasingly used in renal transplant recipients (RTR), but relatively understudied in this population. We assess the safety of post-transplant anticoagulation with DOACs compared to warfarin.

METHODS

We conducted a retrospective study of RTRs at the Mayo Clinic sites (2011-present) that were anticoagulated for greater than 3 months excluding the 1st month post-transplant. The main safety outcomes were bleeding and all-cause mortality. Concomitant antiplatelet and interacting drugs were noted. DOAC dose adjustment was assessed according to common US prescribing practices, guidelines, and/or FDA labeling.

RESULTS

The median follow-up was longer for RTRs on warfarin (1098 days [IQR 521, 1517]) than DOACs (449 days [IQR 338, 942]). Largely, there were no differences in baseline characteristics and comorbidities between RTRs on DOACs (n = 208; apixaban 91.3%, rivaroxaban 8.7%) versus warfarin (n = 320). There was no difference in post-transplant use of antiplatelets, immunosuppressants, most antifungals assessed, or amiodarone. There was no significant difference in incident major bleeding (8.4 vs. 5.3%, p = 0.89), GI bleeding (4.4% vs. 1.9%, p = 0.98), or intra-cranial hemorrhage (1.9% vs. 1.4%, p = 0.85) between warfarin and DOAC. There was no significant difference in mortality in the warfarin group compared to DOACs when adjusted for follow-up time (22.2% vs. 10.1%, p = 0.21). Rates of post-transplant venous thromboembolism, atrial fibrillation or stroke were similar between the two groups. 32% (n = 67) of patients on DOACs were dose reduced, where 51% of those reductions were warranted. 7% of patients that were not dose reduced should have been.

CONCLUSIONS

DOACs did not have inferior bleeding or mortality outcomes compared to warfarin in RTRs. There was greater use of warfarin compared to DOACs and a high rate of improper DOAC dose reduction.

The association of venous thromboembolism with blood transfusion in kidney transplant patients

BACKGROUND

Red blood cell transfusion (RBCT) is common after kidney transplantation and could have pro-thrombotic effects predisposing to venous thromboembolism (VTE). The risks for developing of VTE after RBCT in kidney transplant patients are unknown.

STUDY DESIGN AND METHODS

This was a retrospective cohort study of adult kidney transplant recipients from 2002 to 2018. The exposure of interest was receipt of RBCT after transplant. Cox proportional hazards models were used to calculate hazard ratios (HR) for the outcomes of venous thromboembolism [VTE] (deep venous thrombosis [DVT] or pulmonary embolism [PE]) using RBCT as a time-varying, cumulative exposure.

RESULTS

Out of 1258 kidney transplants recipients, 468 (37%) were transfused during the study period. Seventy-nine study participants (6.3%) developed VTE, 72 DVT (5.7%), and 22 PE (1.8%). For the receipt of 1, 2, 3-5, and >5 RBCT, compared to individuals never transfused, the number of events and adjusted HR (95%CI) for VTE were 6 (6.2%) HR 1.57 (0.69-3.58), 9 (7.6%) HR 2.54 (1.30-4.96), 15 (11.9%) HR 2.73 (1.38-5.41), and 23 (18.1%) HR 5.77 (2.99-11.14) respectively; for DVT, it was 6 (6.2%) HR 1.94 (0.84-4.48), 9 (7.6%) HR 2.92 (1.44-5.94), 14 (11.1%) HR 3.29 (1.63-6.65), and 21 (16.5%) HR 6.97 (3.53-13.76), respectively. For PE, among transfused individuals, there were 14 events (3.0%) and the HR was 2.40 (1.02-5.61).

CONCLUSION

The risks for developing VTE, DVT, and PE were significantly increased in kidney transplant patients receiving RBCT after transplant. Receipt of RBCT should prompt considerations for judicious monitoring and assessment for thrombosis.

First World Consensus Conference on pancreas transplantation: Part II - recommendations

The First World Consensus Conference on Pancreas Transplantation provided 49 jury deliberations regarding the impact of pancreas transplantation on the treatment of diabetic patients, and 110 experts' recommendations for the practice of pancreas transplantation. The main message from this consensus conference is that both simultaneous pancreas-kidney transplantation (SPK) and pancreas transplantation alone can improve long-term patient survival, and all types of pancreas transplantation dramatically improve the quality of life of recipients. Pancreas transplantation may also improve the course of chronic complications of diabetes, depending on their severity. Therefore, the advantages of pancreas transplantation appear to clearly surpass potential disadvantages. Pancreas after kidney transplantation increases the risk of mortality only in the early period after transplantation, but is associated with improved life expectancy thereafter. Additionally, preemptive SPK, when compared to SPK performed in patients undergoing dialysis, appears to be associated with improved outcomes. Time on dialysis has negative prognostic implications in SPK recipients. Increased long-term survival, improvement in the course of diabetic complications, and amelioration of quality of life justify preferential allocation of kidney grafts to SPK recipients. Audience discussions and live voting are available online at the following URL address: http://mediaeventi.unipi.it/category/1st-world-consensus-conference-of-pancreas-transplantation/246.

Outcomes of an Inpatient Dialysis Start in Patients With Kidney Graft Failure: A Population-Based Multicentre Cohort Study

Background:

The frequency and outcomes of starting maintenance dialysis in the hospital as an inpatient in kidney transplant recipients with graft failure are poorly understood.

Objective:

To determine the frequency of inpatient dialysis starts in patients with kidney graft failure and examine whether dialysis start status (hospital inpatient vs outpatient setting) is associated with all-cause mortality and kidney re-transplantation.

Design:

Population-based cohort study.

Setting:

We used linked administrative healthcare databases from Ontario, Canada.

Patients:

We included 1164 patients with kidney graft failure from 1994 to 2016.

Measurements:

All-cause mortality and kidney re-transplantation.

Methods:

The cumulative incidence function was used to calculate the cumulative incidence of all-cause mortality and kidney re-transplantation, accounting for competing risks. Subdistribution hazard ratios from the Fine and Gray model were used to examine the relationship between inpatient dialysis starts (vs outpatient dialysis start [reference]) and the dependent variables (ie, mortality or re-transplant).

Results:

We included 1164 patients with kidney graft failure. More than half (55.8%) of patients with kidney graft failure, initiated dialysis as an inpatient. Compared with outpatient dialysis starters, inpatient dialysis starters had a significantly higher cumulative incidence of mortality and a significantly lower incidence of kidney re-transplantation (P < .001). The 10-year cumulative incidence of mortality was 51.9% (95% confidence interval [CI]: 47.4, 56.9%) (inpatient) and 35.3% (95% CI: 31.1, 40.1%) (outpatient). After adjusting for clinical characteristics, we found inpatient dialysis starters had a significantly increased hazard of mortality in the first year after graft failure (hazard ratio: 2.18 [95% CI: 1.43, 3.33]) but at 1+ years there was no significant difference between groups.

Limitations:

Possibility of residual confounding and unable to determine inpatient dialysis starts that were unavoidable.

Conclusions:

In this study we identified that most patients with kidney graft failure had inpatient dialysis starts, which was associated with an increased risk of mortality. Further research is needed to better understand the reasons for an inpatient dialysis start in this patient population.

Graft Function, Albuminuria, and the Risk of Hemorrhage and Thrombosis After Kidney Transplantation

Background:

Compared to the general population, kidney transplant recipients are at increased risk of hemorrhage and thrombosis. Whether this risk is affected by graft function and albuminuria is unknown.

Objective:

To determine the association between graft function and albuminuria and the risk of post-transplant hemorrhage and thrombosis.

Design:

Retrospective cohort study.

Setting:

We used linked health care databases in Alberta, Canada.

Patients/sample/participants:

We included adult kidney transplant recipients from 2002 to 2015 with a functioning graft at 1 year.

Measurements:

Estimated glomerular filtration rate (eGFR) and albuminuria measurements at 1 year post-transplant were used to categorize recipients (eGFR: ≥45 vs. <45 mL/min/1.73 m²; albuminuria: absence vs. presence). We determined the rates of post-transplant hemorrhage and venous thrombosis based on validated diagnostic and procedural codes.

Methods:

We determined the association between categories of eGFR and albuminuria and post-transplant hemorrhage and venous thrombosis using Poisson regression with log link.

Results:

Of 1284 kidney transplant recipients, 21% had an eGFR <45 mL/min/1.73 m² and 40% had presence of albuminuria at 1 year post-transplant. Over a median follow-up of 6 years, there were 100 hemorrhages (12.6 events per 1000 person-years) and 57 venous thrombosis events (7.1 events per 1000 person-years). The age- and sex-adjusted rate of hemorrhage and thrombosis was over 2-fold higher in recipients with lower eGFR and presence of albuminuria compared to higher eGFR and no albuminuria (hemorrhage: incidence rate ratio, IRR, 2.6, 95% confidence interval [CI]: 1.5-4.4, P = .001; thrombosis: IRR, 2.3, 95% CI: 1.1-5.0, P = .046).

Limitations:

Complete relevant medication information, such as anticoagulants, were not available in our datasets. Due to sample size, this study was underpowered to conduct a fully adjusted analysis.

Conclusion:

Among kidney transplant recipients, lower eGFR and presence of albuminuria at 1 year post-transplant were associated with an over 2-fold higher risk of hemorrhage and venous thrombosis. Graft function and albuminuria at 1 year post-transplant are important prognostic factors in determining risk of post-transplant hemorrhage and venous thrombosis. Further research, including medication data, are needed to further delineate outcomes and safety.

Trial registration:

Not applicable (cohort study).

Anticoagulation in Patients With Advanced Chronic Kidney Disease: Walking the Fine Line Between Benefit and Harm

Chronic kidney disease affects more than 3 million Canadians and is highly associated with cardiovascular diseases that require anticoagulation, such as atrial fibrillation and venous thromboembolism. Patients with chronic kidney disease are at a problematic crossroads; they are at high risk of thrombotic conditions requiring anticoagulation and bleeding complications due to anticoagulation. The limited high-quality clinical evidence to guide decision-making in this area further compounds the dilemma. In this review, we discuss the physiology and epidemiology of bleeding and thrombosis in patients with kidney disease. We specifically focus on patients with advanced kidney disease (estimated glomerular filtration rate ≤ 30 mL/min) or who are receiving dialysis and focus on the nephrologist perspective regarding these issues. We summarize the existing evidence for anticoagulation use in the prevention of stroke with atrial fibrillation and provide practical clinical recommendations for considering anticoagulation use in this population. Last, we examine specific scenarios such as the use of a glomerular filtration rate estimating equation and dosing, the use of existing prediction tools for stroke and hemorrhage risk, current patterns of anticoagulation use (including during the dialysis procedure), and vascular calcification with vitamin K antagonist use in patients with chronic kidney disease.

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.

Venous thromboembolism, factor VIII and chronic kidney disease

Chronic kidney disease (CKD) affects 30 million Americans and is associated with approximately a two-fold increased risk of venous thromboembolism (VTE). There is a graded increased risk of VTE across declining kidney function, as measured by estimated glomerular filtration rate (eGFR) and albuminuria. When patients with end-stage kidney disease (ESKD) experience VTE they are more likely than the general population to be hospitalized and they have a higher mortality. The incidence and consequences of VTE may also differ depending on the cause of kidney disease. In addition, kidney transplant patients with VTE are at a greater risk for death and graft loss than transplant patients without VTE. The reasons that patients with CKD are at increased risk of VTE are not well understood, but recent data suggest that factor VIII is a mediator. Factor VIII is an essential cofactor in the coagulation cascade and a strong risk factor for VTE in general. It is inversely correlated with eGFR and prospective studies demonstrate that factor VIII activity predicts incident CKD and rapid eGFR decline. The etiology of CKD may also influence factor VIII levels. This review summarizes the epidemiology VTE in CKD and reviews the biochemistry of factor VIII and determinants of its levels, including von Willebrand factor and ABO blood group. We explore mechanisms by which the complications of CKD might give rise to higher factor VIII and suggests future research directions to understand how factor VIII and CKD are linked.

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.