Direct oral anticoagulant therapy in adolescent venous thromboembolism: A systematic review.

Adolescent venous thromboembolism (VTE) has unique challenges in management, complications, and compliance to anticoagulants. Direct oral anticoagulants (DOACs) have been approved for pediatric VTE management, with an increasing use especially in adolescents. Primary objective is to evaluate the safety and efficacy of DOAC therapy in adolescent VTE. Secondary objectives include adverse events, bleeding events, and overall mortality. A SR protocol was registered in PROSPERO 2022 (CRD42022363928). Databases were searched from inception to September 22, 2022. Studies with children aged 10-18 years, VTE diagnosis, DOAC therapy, randomized control trials (RCTs), cohort, and relevant study types were included. Studies including prophylaxis, non-DOAC therapy, arterial thrombosis, age outliers, non-relevant study types were excluded. Findings are reported in accordance to PRISMA 2020. Nine reports from five studies, published between 2016 and 2022, were included. Rivaroxaban was the most common DOAC. VTE recurrence was 0.02% in the rivaroxaban phase III trial and one patient in the dabigatran phase IIb/III trial. Complete/partial thrombus resolution (CR/PR) was 76.6% in the rivaroxaban phase III trial, and 83.9% in the dabigatran phase IIb/III trial. CR/PR was found to be 68.4% in Dhaliwal et al. study and 83.3% in Hassan et al. study. Major bleeding occurred in one patient. Headache and gastrointestinal symptoms were commonly seen. All-cause mortality occurred in a patient due to cancer progression. DOAC therapy in adolescent VTE had CR/PR in two-thirds of the patients, with low incidence of VTE recurrence and major bleeding. As there are only two randomized controlled trial (RCTs), future adolescents' studies are required to validate our results.

Thromboprophylaxis Use in Paediatric Inflammatory Bowel Disease: An International RAND Appropriateness Panel.

BACKGROUND AND AIMS: Thromboprophylaxis use in paediatric inflammatory bowel disease [IBD] is inconsistent. Current guidelines only support treating children with acute severe colitis with risk factors. We convened an international RAND panel to explore thromboprophylaxis in paediatric IBD inpatients in the context of new evidence. METHODS: We convened a geographically diverse 14-person panel of paediatric gastroenterologists alongside supporting experts. An online survey was sent before an online meeting. Panellists were asked to rate the appropriateness of thromboprophylaxis in hospitalised paediatric IBD patients via 27 scenarios of varying ages, gender, and phenotype, with and without thrombotic risk factors. Anonymised results were presented at the meeting. A second modified survey was distributed to all panellists present at the meeting. Results from the second survey constitute the RAND panel results. The validated RAND disagreement index defined disagreement when ≥ 1. RESULTS: The combined outcome of thromboprophylaxis being considered appropriate until discharge and inappropriate to withhold was seen in 20 of 27 scenarios, including: all patients with new-onset acute severe colitis; all flares of known ulcerative colitis, irrespective of risk factors except in pre-pubescent patients with limited disease and no risk factors; and all Crohn's patients with risk factors. Disagreement was seen in five scenarios regarding Crohn's without risk factors, where outcomes were already uncertain. CONCLUSIONS: RAND panels are an established method to assess expert opinion in areas of limited evidence. This work therefore constitutes neither a guideline nor a consensus; however, the findings suggest a need to re-evaluate the role of thromboprophylaxis in future guidelines.

Use of rotational thromboelastometry to predict hemostatic complications in pediatric patients undergoing extracorporeal membrane oxygenation: A retrospective cohort study.

BACKGROUND: The incidence of hemostatic complications in pediatric patients undergoing extracorporeal membrane oxygenation (ECMO) is high. The optimal anticoagulation strategy in children undergoing ECMO is unknown. OBJECTIVES: To study the association between hemostatic complications, coagulation tests, and clinical parameters in pediatric patients undergoing ECMO and their effect on survival. METHODS: We performed a retrospective cohort study of pediatric patients undergoing centrifugal pump ECMO. Collected data included patient characteristics, risk factors, and coagulation test results. Statistical analysis was done using logistic regression analysis for repeated measurements. Dependent variables were thrombosis and bleeding, independent variables were rotational thromboelastometry (ROTEM), activated partial thromboplastin time (aPTT) and antifactor-Xa assay (aXa) results, ECMO duration, age <29 days, sepsis and surgery. RESULTS: Seventy-three patients with 623 ECMO days were included. Cumulative incidences of thrombosis and bleeding were 43.5% (95% confidence interval [CI], 26.0%-59.8%) and 25.4% (95% CI, 13.4%-39.3%), respectively. A lower maximum clot firmness of intrinsic ROTEM (INTEM; odds ratio [OR], 0.946; 95% CI, 0.920-0.969), extrinsic ROTEM (OR, 0.945; 95% CI, 0.912-0.973), and INTEM with heparinase (OR, 0.936; 95% CI, 0.896-0.968); higher activated partial thromboplastin time aPTT; OR, 1.020; 95% CI, 1.006-1.024) and age <29 days (OR, 2.900; 95% CI, 1.282-6.694); surgery (OR, 4.426; 95% CI, 1.543-12.694); and longer ECMO duration (OR, 1.149; 95% CI, 1.022-1.292) significantly increased thrombotic risk. Surgery (OR, 2.698; 95% CI, 1.543-12.694) and age <29 days (OR 2.242, 95% CI 1.282-6.694) were significantly associated with major bleeding. Patients with hemostatic complications had significantly decreased survival to hospital discharge (P = .009). CONCLUSION: The results of this study help elucidate the role of ROTEM, aPTT, anti-factor Xa, and clinical risk factors in predicting hemostatic complications in pediatric patients undergoing ECMO.

Venous Thrombosis in Children with Acute Lymphoblastic Leukemia Treated on DCOG ALL-9 and ALL-10 Protocols: The Effect of Fresh Frozen Plasma.

Background Venous thromboembolism (VTE) is an important complication for treatment of acute lymphoblastic leukemia (ALL) in children. Especially, ALL treatment, with therapeutics such as asparaginase and steroids, increases the thrombotic risk by reduction in procoagulant and anticoagulant proteins. Replacement of deficient natural anticoagulants by administration of fresh frozen plasma (FFP) may have a preventive effect on the occurrence of VTE. Methods We retrospectively analyzed all consecutive children (≤18 years) with ALL, treated on the Dutch Childhood Oncology Group (DCOG) ALL-9 and ALL-10 protocols at the Emma Children's Hospital Academic Medical Center between February 1997 and January 2012, to study the effect of FFP on VTE incidence, antithrombin and fibrinogen plasma levels, and VTE risk factors. Results In total, 18/205 patients developed VTE (8.8%; 95% confidence interval [CI]: 4.9-12.7%). In all patients, VTE occurred after asparaginase administration. In total, 82/205 patients (40%) received FFP. FFP supplementation did not prevent VTE or alter plasma levels of antithrombin or fibrinogen. In the multivariate analysis, VTE occurred significantly more frequently in children ≥12 years (odds ratio [OR]: 3.89; 95% CI: 1.29-11.73) and treated according to the ALL-10 protocol (OR: 3.71; 95% CI: 1.13-12.17). Conclusion FFP supplementation does not seem to be beneficial in the prevention of VTE in pediatric ALL patients. In addition, age ≥12 years and treatment according to the DCOG ALL-10 protocol with intensive and prolonged administration of asparaginase in combination with prednisone are risk factors. There is a need for effective preventive strategies in ALL patients at high risk for VTE.

Venous thromboembolism in a large cohort of children with acute lymphoblastic leukemia: Risk factors and effect on prognosis.

BACKGROUND: Venous thromboembolism (VTE) is relatively common in children with acute lymphoblastic leukemia (ALL). Thrombotic risk factors in ALL are asparaginase and steroids. However, within the ALL populations treated on the same regimen, it is less clear which other risk factors play a role. Furthermore, few data are available on the effect of VTE on ALL outcomes. METHODS: In 778 children (1-18 years) with newly diagnosed precursor-B-lineage or T-lineage ALL, treated in the Dutch Childhood Oncology Group (DCOG) ALL-10 protocol in the Netherlands (October 2004 to April 2013), we conducted a nested case control study with 59 VTE cases and 118 controls to identify risk factors for VTE. RESULTS: Fifty-nine of 778 ALL patients developed VTE (7.6%), with cerebral venous sinus thrombosis (CVST) in 26 of 59 patients (44.1%). VTE occurred during induction treatment in 59.3% (n = 35) and in 40.7% (n = 24) during medium risk intensification. Conditional multivariable logistic regression analysis showed that age and ALL subtype were significantly associated with VTE (age ≥7 years: OR 2.72, 95% CI 1.33-5.57; ALL subtype T-ALL: OR 2.95, 95% CI 1.02-8.57). A multivariable Cox model showed no association between the occurrence of VTE and event free survival. In CVST patients, permanent disability was present in 34.6%. CONCLUSION: Within this large pediatric ALL cohort, we demonstrated a high morbidity in CVST patients. Age ≥7 years at diagnosis and T-ALL subtype were the main risk factors for VTE, and should be considered in preventive strategies.

Pediatric Diamond-Blackfan anemia in the Netherlands: An overview of clinical characteristics and underlying molecular defects.

INTRODUCTION: Diamond-Blackfan anemia (DBA) is characterized by hypoplastic anemia, congenital anomalies, and a predisposition for malignancies. Most of our understanding of this disorder stems from molecular studies combined with extensive data input from international patient registries. OBJECTIVES: To create an overview of the pediatric DBA population in the Netherlands. METHODS: Forty-three patients diagnosed with DBA from all Dutch university pediatric hospitals were included in this study, and their clinical and genetic characteristics were collected from patient records. RESULTS: Congenital malformations were present in 24 of 43 patients (55.8%). An underlying genetic defect was identified in 26 of 43 patients (60.5%), the majority of which were found in the RPS19 gene (12 of 43, 27.9%) with 1 patient carrying a mutation in a novel DBA candidate gene, RPL9. In 31 of 35 (88.6%) patients, an initial response to glucocorticoid treatment was observed. Six patients (14.0%) underwent hematopoietic stem cell transplantation, and eleven patients (11 of 43, 25.6%) became treatment-independent spontaneously. CONCLUSION: In agreement with previous reports, the Dutch pediatric DBA population is both clinically and genetically heterogeneous. National and international registries, together with more extensive genetic testing, are crucial to increase our understanding of genotype and phenotype correlations of this intriguing disorder.

Antithrombotic treatment in neonates and children.

Despite the increasing incidence of venous thromboembolic disease in pediatric patients, it remains a rare complication in childhood. Particularly neonates and adolescents are at risk for development of venous thrombosis. Spontaneous thrombotic events are sporadic, the majority of children have multiple coexisting risk factors, including central venous catheter, asphyxia, congenital heart disease, infection, malignancy, surgery and hypovolemia. Most thrombi are diagnosed by ultrasonography. Recommendations for management of pediatric thrombosis are typically extrapolated from adult studies, despite many differences between adults and children, including developmental hemostasis. This review will focus on the management of venous thrombosis in neonates and children, and discuss the use of the available antithrombotic agents in both age categories with reference to those differences.

Increasing Incidence and Recurrence Rate of Venous Thromboembolism in Paediatric Oncology Patients in One Single Centre Over 25 Years.

Venous thromboembolism (VTE) is a serious complication in paediatric oncology patients. To identify the incidence, risk factors and recurrence rate of VTE in paediatric oncology patients, an observational, retrospective cohort study of all consecutive children (≤18 years) with malignancies, treated at the Emma Children's Hospital Academic Medical Centre between January 1989 and December 2013, was done. A matched case-control study in children with lymphomas was performed, to identify thrombotic risk factors. Cumulative recurrence-free survival after first VTE was estimated by the Kaplan-Meier method. Of the 2,183 children included (male: female = 1.4:1.0; median age, 6.6 years) with cancer, 78 patients developed VTE (3.6%; 95% confidence interval [CI], 2.8-4.4). The incidence increased from 0.8% (4/478, 95% CI, 0.0-1.6) between 1989 and 1993 to 10.4% (44/423, 95% CI, 7.6-13.4) between 2009 and 2013. Independent risk factors for VTE were age ≥ 12 years, acute lymphoblastic leukaemia (ALL) and lymphoma. The case-control study in lymphoma patients showed a trend for increased VTE incidence in stage IV lymphoma. Twelve (15.4%) patients developed recurrent thrombosis, 7 patients while on therapeutic or prophylactic anticoagulation. The cumulative recurrence-free survival after first VTE was 88.5, 87.1 and 80.6% after 1, 5 and 10 years, respectively. In conclusion, we demonstrated an increasing incidence of VTE in children with malignancies, with age ≥ 12 years, ALL and lymphoma as independent risk factors. The elevated recurrence rate underlines the importance of full anticoagulant therapy and might warrant prophylactic anticoagulation after first VTE during cancer treatment.

Prevention of central venous catheter-associated bloodstream infections in paediatric oncology patients using 70% ethanol locks: A randomised controlled multi-centre trial.

BACKGROUND: The prevention of central venous catheter (CVC) associated bloodstream infections (CABSIs) in paediatric oncology patients is essential. Ethanol locks can eliminate pathogens colonising CVCs and microbial resistance is rare. Aim of this study was to determine whether two hour 70% ethanol locks can reduce CABSI in paediatric oncology patients. METHODS: We conducted a randomised, double blind, multi-centre trial in paediatric oncology patients (1-18 years) with newly inserted CVCs. Patients were randomly assigned to receive two hour ethanol locks (1.5 or 3 ml 70%) or heparin locks (1.5 or 3 ml 100 IU/ml), whenever it was needed to use the CVC, maximum frequency once weekly. Primary outcomes were time to CABSI or death due to CABSI. RESULTS: We recruited 307 patients (ethanol, n=153; heparin, n=154). In the ethanol group, 16/153 (10%) patients developed a CABSI versus 29/154 (19%) in the heparin group. The incidence of CABSI was 0.77/1000 and 1.46/1000 catheter days respectively (p=0.039). The number-needed-to-treat was 13. No patients died of CABSI. In particular, Gram-positive CABSIs were reduced (ethanol, n=8; heparin, n=21; p=0.012). Fewer CVCs were removed because of CABSI in the ethanol group (p=0.077). The ethanol lock patients experienced significantly more transient symptoms compared to the heparin lock patients (maximum grade 2) (nausea, p=0.030; taste alteration, p<0.001; dizziness, p=0.001; blushing, p<0.001), no suspected unexpected serious adverse reactions (SUSAR) occurred. CONCLUSIONS: This is the first randomised controlled trial to show that ethanol locks can prevent CABSI in paediatric oncology patients, in particular CABSI caused by Gram-positive bacteria. Implementation of ethanol locks in clinical practice should be considered.

Chronic Complications After Femoral Central Venous Catheter-related Thrombosis in Critically Ill Children.

Prescription of thromboprophylaxis is not a common practice in pediatric intensive care units. Most thrombi are catheter-related and asymptomatic, without causing acute complications. However, chronic complications of these (a)symptomatic catheter-related thrombi, that is, postthrombotic syndrome (PTS) and residual thrombosis have not been studied. To investigate these complications, critically ill children of 1 tertiary center with percutaneous inserted femoral central venous catheters (FCVCs) were prospectively followed. Symptomatic FCVC-thrombosis occurred in 10 of the 134 children (7.5%; 95% confidence interval [CI], 2.4-9.5). Only FCVC-infection appeared to be independently associated (P=0.001) with FCVC-thrombosis. At follow-up 2 of the 5 survivors diagnosed with symptomatic thrombosis developed mild PTS; one of them had an occluded vein on ultrasonography. A survivor without PTS had a partial occluded vein at follow-up. Asymptomatic FCVC-thrombosis occurred in 3 of the 42 children (7.1%; 95% CI, 0.0-16.7) screened by ultrasonography within 72 hours after catheter removal. At follow-up, mild PTS was present in 6 of the 33 (18.2%; 95% CI, 6.1-30.3) screened children. Partial and total vein occlusion was present in 1 (3%) and 4 (12%) children, respectively. In conclusion, children on pediatric intensive care units are at risk for (a)symptomatic FCVC-thrombosis, especially children with FCVC-infection. Chronic complications of FCVC-thrombosis are common. Therefore, thromboprophylaxis guidelines are warranted in pediatric intensive care units to minimize morbidity as a result of FCVC-thrombosis.

Supportive care in pediatric cancer: the road to prevention of thrombosis.

The survival rate of children with cancer has increased impressively to almost 80% over the last decades as a result of improved diagnostic procedures and multimodal treatment strategies. Therefore, it becomes more and more important to prevent mortality and morbidity of treatment-associated complications, including venous thromboembolism (VTE). VTE occurs predominantly in children with acute lymphoblastic leukemia, lymphoma, and sarcoma. Pathogenesis of thrombosis in children with cancer is multifactorial. Thrombosis develops due to a combination of the primary disease itself, chemotherapy and supportive care, associated complications, and inherited prothrombotic risk factors probably contributed to the development of thrombosis in these children. Mortality as a result of VTE is low, but both symptomatic and asymptomatic thrombosis cause significant morbidity to justify primary thromboprophylaxis in children with cancer. Identification of risk factors is important to develop predictive models to identify patients at highest risk of thrombosis. Due to variations in risk factors, these models should be tailored to treatment protocols and patient populations. Multicenter studies are needed to investigate which prophylactic strategies are effective and safe to prevent thrombosis in children with cancer.

Nadroparin therapy in pediatric patients with venous thromboembolic disease.

Low-molecular-weight heparins are increasingly used for treatment of pediatric venous thromboembolic disease (VTE). Pediatric data about therapeutic doses of nadroparin are not available. To evaluate pharmacodynamics and safety of therapeutic doses of nadroparin, consecutive patients (age 0 to 18 y) with objectively diagnosed VTE and treated with nadroparin were included in this single center study over a 12-year period. All patients started with 85.5 IU/kg of nadroparin twice daily. The target therapeutic range (TTR) was set at 0.5 to 1.0 anti-Xa IU/mL 4 hours postdose. Safety end points were major bleeding and therapy-related death. A total of 84 patients were enrolled, of whom 8 patients did not undergo measurement of anti-Xa levels. Fifty-four (71%) of 76 patients achieved TTR. The maintenance dose (mean+/-SE) was 448+/-42 IU/kg/d in neonates (<2 mo, n=6), 253+/-22 IU/kg/d in infants (2 mo to 1 y, n=10), 214+/-8 IU/kg/d in children (2 to 11 y, n=13), and 183+/-5 IU/kg/d in adolescents (12 to 18 y, n=25). Neonates required significantly more dose adjustments and time to achieve TTR than adolescents. No major bleeding or therapy-related death occurred. In summary, an age-dependent response to nadroparin exists in pediatric patients. Nadroparin therapy seems to be safe for treatment of pediatric VTE.

Postvaricella purpura fulminans caused by acquired protein s deficiency resulting from antiprotein s antibodies: search for the epitopes.

Postvaricella purpura fulminans is a rare disease in children that is probably caused by an acquired protein S deficiency resulting from antiprotein S antibodies. The epitope of these antibodies is unknown. A 5-year-old girl is described with postvaricella purpura fulminans and an acquired protein S deficiency. In this patient and in her 3-year-old sister with uncomplicated varicella, the concentrations of antiprotein S antibodies were measured and followed with enzyme-linked immunosorbent assay techniques. The epitope of the antiprotein S antibodies was studied using miniprotein S, a recombinant variant of protein S that consists of the first 242 amino acids of protein S, lacking the sex hormone binding globulin-like domain. In the patient's plasma, concentrations of free protein S antigen and total protein S antigen reached normal levels in 4 months and 5 weeks, respectively. The concentrations of the antiprotein S antibodies decreased to 25% of the initial level in the course of 5 months. In the sister, antiprotein S antibodies were present as well, but the concentrations were lower than those in the patient. Most of the antiprotein S antibodies were directed against the first 242 amino acids of protein S. After varicella, a heterozygous autoantibody response may develop that may result in severe acquired protein S deficiency leading to purpura fulminans. Epitopes of these antiprotein S antibodies are situated on both the first 242 amino acids of protein S and the sex hormone binding globulin-like domain.