Markers of hypercoagulability in children with newly diagnosed acute lymphoblastic leukemia.

BACKGROUND: Venous thromboembolism (VTE) is a known complication for children with acute lymphoblastic leukemia (ALL). The aim of this study was to identify laboratory biomarkers that predict which children with ALL are at risk for VTE during induction chemotherapy. MATERIALS AND METHODS: Newly diagnosed ALL patients admitted to Children's Hospital Los Angeles with a central venous catheter (CVC) were eligible to participate. Participants' blood samples (complete blood count [CBC], quantitative D-dimer, prothrombin fragment 1.2 [PTF 1.2], and thrombin-antithrombin complexes [TAT]) were collected at day 0 (baseline/prior to induction), day 7 (±2 days), day 14 (±2 days), day 21 (±2 days), and day 28 (±2 days) of induction chemotherapy or until participants presented with a symptomatic VTE. RESULTS: Seventy-five participants aged 1-21 years were enrolled and included in the final analysis. Twenty-six (35%) of the 75 participants were diagnosed with a CVC-associated VTE (22 asymptomatic and four symptomatic). There was a statistically significant difference between VTE and non-VTE participants for D-dimer (odds ratio [OR] 1.61, 95% confidence interval [CI]: 1.59-1.64), TAT (OR 1.34, 95% CI: 1.32-1.38), and PTF 1.2 (OR 1.31, 95% CI: 1.25-1.37) at all time points. Participants >10 years had a significantly higher risk of developing a VTE compared to participants <4 years (p = .007). CONCLUSION: Older children with ALL as well as those with an elevated TAT, PTF 1.2, or D-dimer showed an increased risk of VTE, which may hold potential for predicting VTE in future studies.

Allergic reactions and antiasparaginase antibodies in children with high-risk acute lymphoblastic leukemia: A children's oncology group report.

BACKGROUND: The objectives of this study were to assess the incidence of clinical allergy and end-induction antiasparaginase (anti-ASNase) antibodies in children with high-risk acute lymphoblastic leukemia treated with pegylated (PEG) Escherichia coli ASNase and to determine whether they carry any prognostic significance. METHODS: Of 2057 eligible patients, 1155 were allocated to augmented arms in which PEG ASNase replaced native ASNase postinduction. Erwinia chrysanthemi (Erwinia) ASNase could be used to replace native ASNase after allergy, if available. Allergy and survival data were complete for 990 patients. End-induction antibody titers were available for 600 patients. RESULTS: During the consolidation phase, 289 of 990 patients (29.2%) had an allergic reaction. There were fewer allergic reactions to Erwinia ASNase than to native ASNase (odds ratio, 4.33; P < .0001) or PEG ASNase (odds ratio, 3.08; P < .0001) only during phase 1 of interim maintenance. There was no significant difference in 5-year event-free survival (EFS) between patients who received PEG ASNase throughout the entire study postinduction versus those who developed an allergic reaction to PEG ASNase during consolidation phase and subsequently received Erwinia ASNase (80.8% ± 2.8% and 81.6% ± 3.8%, respectively; P = .66). Patients who had positive antibody titers postinduction were more likely to have an allergic reaction to PEG ASNase (odds ratio, 2.4; P < .001). The 5-year EFS rate between patients who had negative versus positive antibody titers (80% ± 2.6% and 77.7% ± 4.3%, respectively; P = .68) and between patients who did not receive any ASNase postconsolidation and those who received PEG ASNase throughout the study (P = .22) were significantly different. CONCLUSIONS: The current results demonstrate differences in the incidence rates of toxicity between ASNase preparations but not in EFS. The presence of anti-ASNase antibodies did not affect EFS.

Corrigendum to 'Efficacy of emicizumab is maintained throughout dosing intervals for bleed prophylaxis' [Research and Practice in Thrombosis and Haemostasis, Volume 7, Issue 2, February 2023, 100077].

[This corrects the article DOI: 10.1016/j.rpth.2023.100077.].

Efficacy of emicizumab is maintained throughout dosing intervals for bleed prophylaxis.

Background: Across the HAVEN clinical trial program, the efficacy of emicizumab has been demonstrated in children, adolescents, and adults with hemophilia A, with or without factor VIII inhibitors. After the 4-week loading dose period, emicizumab concentrations are expected to remain at levels that provide bleed protection throughout the entire dosing interval, regardless of the chosen maintenance dosing regimen, ie, weekly, every 2 weeks, or every 4 weeks. Objectives: The objective of this study was to examine the timing of treated bleeds within the dosing intervals for emicizumab administered during the HAVEN 1 to 4 studies. Methods: In this post hoc analysis, we pooled data from all the participants of the HAVEN 1 to 4 studies and analyzed the timing of treated bleeds in relation to the emicizumab dose. Results: A total of 392 participants were included in this analysis, with a median (range) age of 28.0 years (1.1-77.0 years). Target joints were identified in 237 of 392 (60.5%) participants before the study entry. Overall, 211 of 392 (53.8%) participants experienced 907 treated bleeding events. The total mean (SD) annualized bleeding rate across the 4 studies was 1.6 (5.9). There was no evidence that bleeding events clustered on any 1 particular day in any dosing schedule from HAVEN 1 to 4 (P > .05 for all 3 treatment regimens). Conclusion: Data from the HAVEN 1 to 4 trials show consistent bleed prevention within the dosing interval, regardless of the dosing regimen chosen. These findings provide further evidence of the sustained efficacy of emicizumab across all approved dosing regimens to reduce bleeding in people with hemophilia A.

Surgical outcomes in people with hemophilia A taking emicizumab prophylaxis: experience from the HAVEN 1-4 studies.

Many people with hemophilia A (PwHA) undergo surgery in their lifetime, often because of complications of their disease. Emicizumab is the first bispecific monoclonal antibody prophylactic therapy for PwHA, and its efficacy and safety have been previously demonstrated; however, there is a need to build an evidence base on the management of PwHA on emicizumab undergoing surgery. Data from the HAVEN 1-4 phase 3 clinical trials were pooled to provide a summary of all minor and major surgeries in PwHA with or without factor VIII (FVIII) inhibitors who were receiving emicizumab prophylaxis. Overall, 233 surgeries were carried out during the HAVEN 1-4 trials: 215 minor surgeries (including minor dental and joint procedures, central venous access device placement or removal, and endoscopies) in 115 PwHA (64 with FVIII inhibitors) and 18 major surgeries (including arthroplasty and synovectomy) in 18 PwHA (10 with FVIII inhibitors). Perioperative hemostatic support was at the discretion of the treating physician. Overall, the median (interquartile range [IQR]) age was 33.5 (13.0-49.0) years and the median (IQR) emicizumab exposure time before surgery was 278.0 (177.0-431.0) days. Among the 215 minor surgeries, 141 (65.6%) were managed without additional prophylactic factor concentrate, and of those, 121 (85.8%) were not associated with a postoperative bleed. The majority (15 of 18 [83.3%]) of major surgeries were managed with additional prophylactic factor concentrate. Twelve (80.0%) of these 15 surgeries were associated with no intraoperative or postoperative bleeds. The data demonstrate that minor and major surgeries can be performed safely in PwHA receiving emicizumab prophylaxis. These trials are registered at www.clinicaltrials.gov as #NCT02622321, #NCT02795767, #NCT02847637, and #NCT03020160.

United States pharmacopeia safety evaluation of spirulina.

The Dietary Supplements Information Expert Committee (DSI-EC) of the United States Pharmacopeial Convention (USP) reviews the safety of dietary supplements and dietary supplement ingredients for the purpose of determining whether they should be admitted as quality monographs into the United States Pharmacopeia and National Formulary (USP-NF). The United States Food and Drug Administration (FDA) has enforcement authority to pursue a misbranding action in those instances where a dietary supplement product indicates that it conforms to USP standards but fails to so conform. Recently DSI-EC undertook a safety evaluation of spirulina, a widely used dietary ingredient. DSI-EC reviewed information from human clinical trials, animal studies, and regulatory and pharmacopeial sources and analyzed 31 adverse event reports regarding spirulina to assess potential health concerns. At the conclusion of this review, DSI-EC assigned a Class A safety rating for Spirulina maxima and S. platensis, thereby permitting the admission of quality monographs for these dietary supplement ingredients in USP-NF. DSI-EC continually monitors reports concerning the safety of dietary supplements and dietary supplement ingredients for which USP dietary supplement monographs are developed. The DSI-EC may revisit the safety classification of spirulina as new information on this dietary ingredient becomes available.

Establishment of a framework for assessing mortality in persons with congenital hemophilia A and its application to an adverse event reporting database.

BACKGROUND: Despite recent therapeutic advances, life expectancy in persons with congenital hemophilia A (PwcHA) remains below that of the non-HA population. As new therapies are introduced, a uniform approach to the assessment of mortality is required for comprehensive evaluation of risk-benefit profiles, timely identification of emerging safety signals, and comparisons between treatments. OBJECTIVES: Develop and test a framework for consistent reporting and analysis of mortality across past, current, and future therapies. PATIENTS/METHODS: We identified known causes of mortality in PwcHA through literature review, analysis of the US Food and Drug Administration Adverse Event Reporting System (FAERS) database, and expert insights. Leading causes of death in general populations are those recognized by the Centers for Disease Control and Prevention and the World Health Organization. We developed an algorithm for assessing fatalities in PwcHA and used this to categorize FAERS data as a proof of concept. RESULTS: PwcHA share mortality causes with the non-HA population including cardiovascular disease, malignancy, infections, pulmonary disease, dementias, and trauma/suicide. Causes associated with HA include hemorrhage, thrombosis, human immunodeficiency virus, hepatitis C virus, and liver dysfunction. We propose an algorithm employing these classes to categorize fatalities and use it to classify FAERS fatality data between 01/01/2000 and 03/31/2020; the most common causes were hemorrhage (22.2%) and thrombosis (10.4%). CONCLUSIONS: A conceptual framework for examining mortality in PwcHA receiving any hemophilia therapy is proposed to analyze and interpret fatalities, enabling consistent and objective assessment. Application of the framework using FAERS data suggests a generally consistent pattern of reported mortality across HA treatments, supporting the utility of this unified approach.

Outcome for children treated for relapsed or refractory acute myelogenous leukemia (rAML): a Therapeutic Advances in Childhood Leukemia (TACL) Consortium study.

BACKGROUND: Current event-free survival (EFS) rates for children with newly diagnosed acute myeloid leukemia (AML) approach 50-60%. We hypothesize that further improvements in survival are unlikely to be achieved with traditional approaches such as dose intensive chemotherapy or hematopoietic stem cell transplants, since these therapies have been rigorously explored in clinical trials. This report highlights efforts to assess the response rates and survival outcomes after first or greater relapse in children with AML. PROCEDURE: We performed a retrospective cohort review of pediatric patients with relapsed and refractory AML (rAML) previously treated at TACL institutions between the years of 1995 and 2004. Data regarding disease characteristics at diagnosis and relapse, treatment response, and survival was collected on 99 patients and 164 medullary relapses or treatment failures. RESULTS: The complete response (CR) rate following the second therapeutic attempt was 56 +/- 5%. CR rates following a third treatment attempt was 25 +/- 8% while 17 +/- 7% achieved CR following the fourth through sixth treatments. The 5-year disease-free survival in patients achieving CR following a second therapeutic attempt was 43 +/- 7%. The 5-year EFS and overall survival (OS) rates for all patients receiving a second treatment attempt was 24 +/- 5% and 29 +/- 5%, respectively. CONCLUSIONS: This CR rate following a second therapeutic attempt and OS rate in patients with rAML is consistent with the literature. There are limited published data of CR rates for subsequent relapses. Our data can serve as a historical benchmark to compare outcomes of future therapeutic trials in rAML against traditional chemotherapy regimens.

United States Pharmacopeia (USP) comprehensive review of the hepatotoxicity of green tea extracts.

As part of the United States Pharmacopeia's ongoing review of dietary supplement safety data, a new comprehensive systematic review on green tea extracts (GTE) has been completed. GTEs may contain hepatotoxic solvent residues, pesticide residues, pyrrolizidine alkaloids and elemental impurities, but no evidence of their involvement in GTE-induced liver injury was found during this review. GTE catechin profiles vary significantly with manufacturing processes. Animal and human data indicate that repeated oral administration of bolus doses of GTE during fasting significantly increases bioavailability of catechins, specifically EGCG, possibly involving saturation of first-pass elimination mechanisms. Toxicological studies show a hepatocellular pattern of liver injury. Published adverse event case reports associate hepatotoxicity with EGCG intake amounts from 140 mg to ∼1000 mg/day and substantial inter-individual variability in susceptibility, possibly due to genetic factors. Based on these findings, USP included a cautionary labeling requirement in its Powdered Decaffeinated Green Tea Extract monograph that reads as follows: "Do not take on an empty stomach. Take with food. Do not use if you have a liver problem and discontinue use and consult a healthcare practitioner if you develop symptoms of liver trouble, such as abdominal pain, dark urine, or jaundice (yellowing of the skin or eyes)."

United States Pharmacopeia review of the black cohosh case reports of hepatotoxicity.

OBJECTIVE: Black cohosh [Actaea racemosa L., formerly Cimicifuga racemosa (L.) Nutt.] is a botanical used mainly for the management of menopausal symptoms. Recently, regulatory agencies in Australia, Canada, and the European Union have released statements regarding the "potential association" between black cohosh and hepatotoxicity. In response, the Dietary Supplement Information Expert Committee of the US Pharmacopeia's Council of Experts reviewed safety information for black cohosh products. DESIGN: The Expert Committee analyzed information from human clinical case reports, adverse event reports, animal pharmacological and toxicological data, historical use, regulatory status, and contemporaneous extent of use. Reports were obtained from diverse sources, including the European Medicines Agency, Health Canada, the Australian Therapeutic Goods Administration, and the US Food and Drug Administration. Case reports pertaining to liver damage were evaluated according to the Naranjo causality algorithm scale. RESULTS: Thirty nonduplicate reports on use of black cohosh products concerning liver damage were analyzed. All the reports of liver damage were assigned possible causality, and none were probable or certain causality. The clinical pharmacokinetic and animal toxicological information did not reveal unfavorable information about black cohosh. CONCLUSIONS: Based on this safety review, the Dietary Supplement Information Expert Committee determined that black cohosh products should be labeled to include a cautionary statement. This is a change from the Expert Committee's decision of 2002, which required no such statement. With this decision, the US Pharmacopeia's Botanical Expert Committee may develop monographs for black cohosh, and the US Pharmacopeia may offer its verification programs to dietary supplement ingredient and product manufacturers.

Safety of green tea extracts : a systematic review by the US Pharmacopeia.

Green tea [Camellia sinensis (L.) Kuntze] is the fourth most commonly used dietary supplement in the US. Recently, regulatory agencies in France and Spain suspended market authorization of a weight-loss product containing green tea extract because of hepatotoxicity concerns. This was followed by publication of adverse event case reports involving green tea products. In response, the US Pharmacopeia (USP) Dietary Supplement Information Expert Committee (DSI EC) systematically reviewed the safety information for green tea products in order to re-evaluate the current safety class to which these products are assigned. DSI EC searched PubMed (January 1966-June 2007) and EMBASE (January 1988-June 2007) for clinical case reports and animal pharmacological or toxicological information. Reports were also obtained from a diverse range of other sources, including published reviews, the US FDA MedWatch programme, USP's MEDMARX adverse event reporting system, the Australian Therapeutic Goods Administration, the UK Medicines and Healthcare products Regulatory Agency, and Health Canada's Canadian Adverse Drug Reaction Monitoring Program. Case reports pertaining to liver damage were evaluated according to the Naranjo causality algorithm scale. In addition, the Committee analysed information concerning historical use, regulatory status, and current extent of use of green tea products. A total of 216 case reports on green tea products were analysed, including 34 reports concerning liver damage. Twenty-seven reports pertaining to liver damage were categorized as possible causality and seven as probable causality. Clinical pharmacokinetic and animal toxicological information indicated that consumption of green tea concentrated extracts on an empty stomach is more likely to lead to adverse effects than consumption in the fed state. Based on this safety review, the DSI EC determined that when dietary supplement products containing green tea extracts are used and formulated appropriately the Committee is unaware of significant safety issues that would prohibit monograph development, provided a caution statement is included in the labelling section. Following this decision, USP's DSI ECs may develop monographs for green tea extracts, and USP may offer its verification programmes related to that dietary ingredient.

The state of dietary supplement adverse event reporting in the United States.

PURPOSE: The Dietary Supplements Information Expert Committee (DSI-EC; the Committee) of the United States Pharmacopeial Convention (USP) reviews safety profiles of dietary supplements before development of USP-National Formulary (USP-NF) quality monographs. Because the veracity of dietary supplement adverse event reports (DS AERs) directly affects DSI-EC safety reviews, the Committee reviewed the current status of DS AER reporting in the US. METHODS: DSI-EC reviewed PubMed searches, information from the US Food and Drug Administration's (FDA) MedWatch program, the Toxic Exposure Surveillance System (TESS) of the American Association of Poison Control Centers (AAPCC), and reports from US and other agencies. DSI-EC analyzed this information to identify key factors that affect the quality of DS AERs. RESULTS: The overall incidence of DS AERs appears generally to be low. However, the primary reporting portal (FDA MedWatch) receives fewer AERs than do poison control centers (PCCs), and limited coordination exists among national and international surveillance programs for evaluating signals that may indicate potential public health risks. Both inadequate and poor-quality reporting of DS AERs are major limitations of DS safety monitoring in the US. CONCLUSIONS: Based on its assessments, the Committee advances recommendations to improve the quality of reporting, monitoring, and assessing DS AERs. These include (1) enhanced data collection approaches, (2) improved coordination of AER surveillance programs, (3) strengthening of educational programs for public and health care sectors, and (4) conduct of research concerning the safety of DS. If taken, these approaches are expected to improve the health and well-being of DS users.

Common problems in critically ill obstetric patients, with an emphasis on pharmacotherapy.

Pharmacological treatment of critically ill obstetric patients can be especially challenging due to the complexity of caring for 2 patients, with a paucity of research to support practice. This review will provide practitioners with primary recommendations for management of the critical illnesses most commonly encountered in pregnancy and will discuss the scientific and clinical merit of these recommendations.

Obesity and risk for venous thromboembolism from contemporary therapy for pediatric acute lymphoblastic leukemia.

INTRODUCTION: Acute lymphoblastic leukemia (ALL) therapy confers risk for venous thromboembolism (VTE) and associated acute and long-term morbidity. Obesity increases VTE risk in the general population but its impact on ALL therapy-associated VTE is unknown. METHODS: In a retrospective cohort of children treated for ALL between 2008 and 2016 (n = 294), we analyzed obesity at diagnosis (body mass index [BMI] ≥95%) and subsequent development of VTE. A subset participated in two concurrent prospective ALL trials studying body composition via dual-energy X-ray absorptiometry (DXA) (n = 35) and hypercoagulability via thromboelastography (TEG) (n = 46). Secondary analyses explored whether precise measurement of body fat and/or global hemostasis ex vivo by TEG could further delineate VTE risk in the obese. RESULTS: Overall, we found 27/294 (9.2%) patients developed symptomatic VTE during therapy, 19/27 (70%) occurred during Induction. Study-defined "serious" VTE developed in 4/294 (1.4%) of patients. Obesity but not overweight was strongly predictive of symptomatic VTE (obesity odds ratio = 3.8, 95% confidence interval 1.5-9.6, p = 0.008). In the DXA subset, only 2/35 patients developed symptomatic VTE. However, within those prospectively screened during Induction, 30% (14/46) developed VTE; eight (17%) of these were asymptomatic and found only via screening. CONCLUSIONS: In this pediatric ALL cohort, obesity conferred more than a three-fold increased risk for symptomatic VTE. In a subgroup of patients who underwent active screening, up to a third were noted to have VTE (symptomatic and asymptomatic). TEG did not predict VTE. Additional studies are necessary to validate these findings and to further refine a risk-stratified approach to thrombo-prevention during ALL therapy.

Venous Thromboembolism in Children with Cancer and Blood Disorders.

Venous thromboembolism (VTE) in children is multifactorial and most often related to a combination of inherited and acquired thrombophilias. Children with cancer and blood disorders are often at risk for VTE due to disease-related factors such as inflammation and abnormal blood flow and treatment-related factors such as central venous catheters and surgery. We will review risk factors for VTE in children with leukemia, lymphoma, and solid tumors. We will also review risk factors for VTE in children with blood disorders with specific focus on sickle cell anemia and hemophilia. We will present the available evidence and clinical guidelines for prevention and treatment of VTE in these populations.

The bleeding newborn: A review of presentation, diagnosis, and management.

The neonatal hemostatic system is continuously developing with rapidly changing concentrations of many coagulation proteins. Thus, determining the etiology of bleeding in a newborn has additional challenges beyond those seen in older children or adults. Bleeding can be seen in both well and sick newborns due to congenital causes, such as hemophilia or von Willebrand disease, and acquired causes, such as liver failure or disseminated intravascular coagulation. Traditional coagulation testing should be interpreted with caution and with the help of a hematologist, if possible, due to the greatly different normal ranges between neonates as compared with older children and adults. However, despite these challenges, both clinical and laboratory clues can guide physicians appropriately to diagnose and treat the bleeding newborn.

Commonly used herbal medicines in the United States: a review.

Herbal medicines are widely used in the United States, with approximately one quarter of adults reporting use of an herb to treat a medical illness within the past year. Herbs contain complicated mixtures of organic chemicals, the levels of which may vary substantially depending upon many factors related to the growth, production, and processing of the herbal product. While many manufacturers attempt to provide products with consistent levels of suspected active ingredients through a process known as standardization, this technique has uncertain effects on the safety and efficacy of the final product. Herbs are considered to be dietary supplements in the United States and therefore are subjected to a very limited form of regulation and oversight. Although herbs are often believed to be "natural" and therefore safe, many dangerous and lethal side effects have recently been reported, including direct toxic effects, allergic reactions, effects from contaminants, and interactions with drugs and other herbs. Of the ten most commonly used herbs in the United States, systematic reviews have concluded that only four are likely to be effective, and there is very limited evidence to evaluate the efficacy of the approximately 20,000 other available herbal products. Because herbs may contain potent bioactive substances and are often marketed to treat specific diseases, many have argued that they should be subject to more stringent regulation, similar to over-the-counter drugs. To improve the safety and consistency of herbs, additional research is needed to define the pharmacology, stability, and bioavailability of these products.

A U.S. perspective on the adverse reactions from traditional Chinese medicines.

BACKGROUND: Traditional Chinese medicines (TCM) are popular in the United States and Asian and non-Asian consumers are using the product for disease treatment and health prevention. As more people are using TCM products, there are increased reports on adverse reactions. This review will focus on adverse reactions due to TCM as reported in the literature. METHODS: The review is based on MedLine search of literatures using keywords including: herbs, herbal, traditional Chinese medicines with toxicity, adverse effects, death, drug interaction and pharmacokinetic. In addition, specific searches were performed using the above keywords with the common name and the scientific name of the plant product. RESULTS: The causes of adverse reactions associated with TCM are diverse. They include variability in active/toxic ingredients due to growing conditions, use of inherent toxic herbs causing toxicity, overdose of herbs, drug-herb interactions especially with pharmaceuticals that have narrow therapeutic index, coexisting diseases, and idiosyncratic reactions like allergy, hepatitis and anaphylaxis. Other adverse reactions can be due to manufacturing and quality problems causing adulteration, misidentification, substitution of one herb with another, variability in the amount of active ingredients, use of pharmaceuticals without identifying on the labels, improper processing and preparation, and contamination. CONCLUSIONS: To minimize the adverse reactions from TCM and protect the public, there must be adequate laws and regulations to ensure that products are manufactured with the highest standards. Manufacturers should be licensed by regulatory agency and manufactured under good manufacturing practice. TCM products must be evaluated for their safety before marketing. Proper labeling and good surveillance systems shall ensure the protection of the consumers.

FondaKIDS II: long-term follow-up data of children receiving fondaparinux for treatment of venous thromboembolic events.

BACKGROUND: The incidence of venous thrombotic events (VTE) and use of anticoagulants in children have both risen over time. It is imperative that safety and efficacy studies of newer anticoagulants include children. OBJECTIVES: The purpose of this study was to investigate the long-term safety, dosing, and efficacy of fondaparinux in children. PATIENTS/METHODS: The study included children 1-18 years old treated with fondaparinux at Children's Hospital Los Angeles. Descriptive statistics were used to present our findings. RESULTS: Data from 35 patients were collected and analyzed. Fourteen of 22 evaluable patients (63.6%) had complete resolution of their thrombus, 6/22 (27.3%) had partial resolution, and 2/22 (9.1%) had no change. Ten patients needed a total of 16 dose adjustments over a median 152 days treatment duration to achieve therapeutic levels. Two patients (9.1%) had VTE recurrence. There were 3 major (intracranial hemorrhage- prior to initiation of fondaparinux, pulmonary hemorrhage, and subretinal hemorrhage) and 6 minor (2 with blood in stool, 1 with injection site, 1 CVC site, 1 tracheostomy bleed, 1 epistaxis) bleeding events. CONCLUSIONS: In this long-term follow-up study on children treated with fondaparinux for VTE, 90.9% of patients had either complete or partial resolution while the recurrence rate was in line with previous studies. There were 9 bleeding events (3 major and 6 minor), though only 1 event required the discontinuation of fondaparinux. Given the advantages of fondaparinux over other anticoagulants, this study suggests that fondaparinux could be considered a safe and effective alternative for the management of VTE in children.