Thrombosis in children with malignancy

Timing of Central Venous Line Insertion During Induction in Children With Acute Lymphoblastic Leukemia

PURPOSE

Central venous lines (CVL) in children with acute lymphoblastic leukemia (ALL) provide comfortable administration of intensive chemotherapy and blood sampling. The optimal time for the insertion of CVL in patients with ALL during induction therapy is controversial. This study aimed to investigate the frequency of CVL-related complications in children with ALL concerning the time of CVL insertion.

PATIENTS AND METHODS

We reviewed the records of 52 pediatric ALL patients with CVL. CVL placement before or on treatment day 15 was defined as "early insertion", and after treatment day 15 was defined as "late insertion". Demographics, preoperative blood counts, type of central line, time of CVL placement, CVL-related complications, and blood counts during complications were all noted. All the data were collected from those with the first catheter use.

RESULTS

CVL was placed ≤15 days in 26 patients (50%) and after 15 days in 26 patients (50%). Regarding the infection rates, no statistical difference was found between early and late CVL-inserted groups ( P =n.s.). Five patients developed thrombosis, and risk was found to be similar between early and late CVL-inserted groups ( P =n.s.). Catheter-related mechanical complications were recorded in 7 patients (3 in early and 4 in late CVL-inserted group, ( P =n.s.).

CONCLUSION

The present study showed no relation between the timing of CVL placement during induction therapy and the occurrence of infection and thrombosis. Our results suggest that CVL can be placed safely at the time of diagnosis or early induction treatment to provide a comfortable administration of chemotherapy and decrease painful blood samplings.

Neurological complications of pediatric cancer

Both the onset of various malignancies as well as the treatment of cancer can lead to neurologic symptoms which can be difficult to diagnose. In this review, we highlight the varied ways in which neurologic sequelae of cancer and its treatment manifest in children. Initial neurologic presentation may be secondary to mass effect or to immune-mediated paraneoplastic syndromes. Treatment effects on the nervous system may arise from surgery, chemotherapy, radiation, or bone marrow transplantation. In addition, the rapidly expanding field of immunotherapies for cancer has generated numerous new approaches to eradicating cancer including monoclonal antibodies, checkpoint inhibitors, and chimeric antigen receptor T cells (CAR-T cells), which have neurologic side effects mediated by immune responses that are also being recognized. Here we review common consult questions to the neurologist and our general approach to these scenarios including altered mental status, headaches, seizures, and sensorimotor complaints, considering the multifactorial nature of each.

Upfront Therapies and Downstream Effects: Navigating Late Effects in Childhood Cancer Survivors in the Current Era

PURPOSE OF REVIEW

As survival rates of those diagnosed with childhood cancer improve over time, the number of long-term survivors continues to grow. Advances have not only been made in the upfront treatment of childhood cancer, but also in the identification and treatment of late complications that may arise as a result of the chemotherapy, radiotherapy, or surgical interventions required to provide a cure.

RECENT FINDINGS

As new therapies emerge that are often more targeted to cancerous cells while sparing healthy tissues, the hope is that cure can be achieved without the same long-term side effects for survivors. However, much is unknown regarding how these novel interventions will impact patients in the years to come. It is critical that we continue to follow patients treated with new modalities in order to identify and treat the long-term complications that may arise in future childhood cancer survivors.

Intermittent Versus Continuous PEG-Asparaginase to Reduce Asparaginase-Associated Toxicities: A NOPHO ALL2008 Randomized Study

PURPOSE

Asparaginase is an essential drug in childhood acute lymphoblastic leukemia (ALL) therapy and is frequently given for months to obtain continuous asparagine depletion. We randomly assigned patients to continuous versus intermittent pegylated-asparaginase (PEG-asp) treatment, hypothesizing there would be decreased toxicity with unchanged efficacy.

METHODS

Children (median age, 4.2 years) treated for non–high-risk ALL according to the Nordic Society for Pediatric Hematology and Oncology ALL2008 protocol received five intramuscular PEG-asp injections (1,000 IU/m2) every two weeks and were then randomly assigned to additional three doses (6-week intervals [experimental arm], n = 309) versus 10 doses (2-week intervals [standard arm], n = 316). The primary end point was noninferior (6% margin) disease-free survival. Toxicity reduction was a secondary end point. Occurrence of asparaginase-associated hypersensitivity, pancreatitis, osteonecrosis, and thromboembolism were prospectively registered.

RESULTS

After a median follow-up of 4.1 years, the 5-year disease-free survival was 92.2% (95% CI, 88.6 to 95.8) and 90.8% (95% CI, 87.0 to 94.6) in the experimental and standard arms, respectively. The 3-year cumulative incidence of any first asparaginase-associated toxicity (hypersensitivity [n = 13]; osteonecrosis [n = 29]; pancreatitis [n = 24]; thromboembolism [n = 17]) was 9.3% in the experimental arm and 18.1% in the standard arm ( P = .001). Asparaginase-associated toxicity reduction was confirmed in sex- and risk-group–adjusted Cox regression analysis stratified by age (≥ 10 and < 10 years; hazard ratio, 0.48; P = .001). The experimental arm had the lowest incidences of all four toxicities, reaching significance for pancreatitis (6-month risk, 5.8% v 1.3%; P = .002).

CONCLUSION

The excellent cure rates and reduced toxicity risk support the use of intermittent PEG-asp therapy after the first 10 weeks in future childhood ALL trials that apply prolonged PEG-asp therapy.

Feasibility and safety of delivering full-dose anticoagulation therapy in children treated according to Dana-Farber Cancer Institute acute lymphoblastic leukemia consortium therapy protocols

BACKGROUND

The literature is void of an evidence-based anticoagulation therapy (ACT) management strategy in the context of thrombocytopenia. We examined the impact of thrombocytopenia on low-molecular-weight heparin (LMWH) dosing and incidence of bleeding in children with acute lymphoblastic leukemia (ALL) or lymphoblastic lymphoma (LL) who developed thromboembolism (TE) during therapy according to DFCI ALL protocols.

PROCEDURE

Patient records from our tertiary care center were reviewed for demographics, details of diagnoses and therapy of ALL/LL and TE diagnoses, platelet counts during ACT, LMWH dosing, and bleeding episodes.

RESULTS

Thirty-nine TEs were diagnosed in 33 patients [mean age 9 years (range, 2.5-18); 16 males and 31 with ALL] during the study period. A majority (85%) of patients were diagnosed with TE in the consolidation phase with mean time to TE 5.75 months from ALL/LL diagnosis. All patients received LMWH, and the median duration of ACT was 5.9 months (range, 1-11 months). Platelets were measured weekly. On 29 occasions, platelet nadir was <50 × 10⁹ /L, and twice it was < 20 × 10⁹ /L. One (3%) patient had major bleeding episode while on ACT. Platelet count at the time of bleeding was 222 × 10⁹ /L. Ninety-two procedures [83 lumbar punctures (LPs), 9 central venous line (CVL) insertion/revision] were completed without bleeding complications. Asparaginase was held temporarily with TE diagnosis in 48% of patients; most (88%) patients completed all scheduled doses as per protocol.

CONCLUSIONS

Ability to administer full-dose LMWH, expected bleeding rate, and completion of asparaginase doses while on ACT suggest full-dose ACT is feasible and safe in children with ALL/LL who develop TE during DFCI ALL consortium therapy protocols.

Advances in predicting venous thromboembolism risk in children

Paediatric venous thromboembolism (VTE) is a rare disorder but a rising incidence has been observed in recent years, due to improved VTE diagnosis and increased use of central venous catheters in the treatment of severe diseases. Risk assessment strategies are well established for adult patients, however, similar guidelines for paediatric patients are largely lacking. Several risk prediction tools have been reported in recent literature, which make use of established risk factors to assess VTE risk in paediatric subgroups, such as hospitalised children, cancer-diagnosed children and paediatric trauma patients. Although these models suffer several limitations regarding their study size and heterogeneous selection of predictor variables, they offer potential for improving the thromboprophylaxis management in these children. Here, we give an overview on recently reported risk prediction models for paediatric VTE.

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.

TropicALL study: Thromboprophylaxis in Children treated for Acute Lymphoblastic Leukemia with Low-molecular-weight heparin: a multicenter randomized controlled trial

Background

Venous thromboembolism (VTE) is a common and severe complication during treatment of acute lymphoblastic leukemia (ALL). An important cause is the intensive use of asparaginase. Prospective cohort studies in which prophylactic low-molecular-weight heparin (LMWH) was used to prevent VTE showed lower VTE risk than in historic control cohorts, with a negligible bleeding risk. However, the efficacy of thromboprophylaxis with LMWH during ALL treatment has never been investigated in a randomized design. Here, we present the protocol of a randomized controlled trial in which the efficacy and safety of thromboprophylaxis with high prophylactic dose LMWH versus no thromboprophylaxis will be assessed in children treated for primary ALL with asparaginase.

Methods/Design

Thromboprophylaxis in Children treated for Acute Lymphoblastic Leukemia with Low-molecular-weight heparin (TropicALL) is a multicenter, randomized controlled open-label trial conducted in the Netherlands. Patients between 1 and 19 years of age with primary ALL, who are treated within the Dutch Childhood Oncology Group (DCOG) ALL-11 or 12 study will be randomized to thromboprophylaxis with LMWH once daily, (dose of 85 IU/kg (intervention arm A)), or to no thromboprophylaxis (arm B, standard of care) during asparaginase courses of ALL treatment. Primary efficacy endpoint is symptomatic objectified VTE during ALL treatment; secondary efficacy endpoints are overall survival and the composite of symptomatic and asymptomatic objectified VTE. Primary safety endpoints are major bleeding, clinically relevant non-major bleeding and minor bleeding. A total of 324 patients will be included to obtain a relative risk reduction of 75% with a power of 80%, using a two-sided test with significance level α = 0.05.

Discussion

This trial will be the first to assess efficacy and safety of thromboprophylaxis with LMWH during asparaginase treatment for ALL in children in a randomized design.

Trail registration

Nederlands Trial Register NTR4707. Registered 30 July 2014.

Incidence and characteristics of venous thrombotic events in pediatric cancer patients: A 20-year experience in the Maritimes, Canada

OBJECTIVE

Venous thrombotic events (VTE) are a well-recognized complication in pediatric cancer patients. Population-based data on the incidence and characteristics of VTE in all pediatric cancer patients are limited. This information is crucial to identify patients at high risk and design targeted interventions accordingly. The present study was designed to determine the incidence and characteristics of VTE in the pediatric oncology population.

PARTICIPANTS

We conducted a retrospective, population-based, cohort study of patients treated in the Maritimes, Canada between 1995 and 2015.

RESULTS

There were 1210 pediatric hematology/oncology patients from the Maritimes, Canada, treated at the IWK Health Centre between 1995 and 2015. Fifty-eight (4.8%) experienced at least 1 VTE and the majority of patients experienced it within 6 months of cancer diagnosis. The median age of patients who experienced VTE was 10.7 years (SD = 6.0). The most common presenting symptom of thrombosis was central venous line dysfunction, and the most common location for thrombosis was within the upper venous system. We observed that 65.6% of the patients with VTE required >1 central venous catheters (CVC). The presence of a VTE increased the odds of requiring >1 CVC to 3.6 (95% confidence interval: 1.76-7.3).

CONCLUSION

Thus, in this large, population-based study, we present the incidence and characteristics of VTE in the pediatric oncology population and demonstrate the clinical impact of VTE in terms of loss of CVC. Larger, prospective studies are required to confirm these findings and to develop a risk model for managing and preventing VTE in this patient population.

Prothrombotic Risk Factors and Preventive Strategies in Adolescent Venous Thromboembolism

Venous thromboembolism (VTE) in adolescents is a serious condition that requires prompt recognition and optimal management to prevent mortality and long-term morbidity. Adolescents account for a large proportion of cases of VTE in children. As teenagers transition from childhood to adulthood, they are at risk of developing medical conditions and exposure to risky habits that predispose them to VTE. This review focuses on the variety of risk factors and comorbidities seen in adolescent VTE and takes a quick look into risk-based preventive strategies for primary and secondary prevention.

Age at cancer diagnosis, non-O blood group and asparaginase therapy are independently associated with deep venous thrombosis in pediatric oncology patients: A risk model

INTRODUCTION

Pediatric oncology patients are at increased risk for deep venous thrombosis (DVT). Determining the sub-population of children at increased DVT risk is critical for optimum clinical management. Therefore, the aim of the current study was to identify clinical risk factors for DVT which are easily identifiable at cancer diagnosis.

MATERIALS AND METHODS

A Canadian multicenter case control study in survivors of childhood cancer. Survivors who had DVT (Cases) while being treated for pediatric cancer where matched by center with a minimum of two survivors who did not experience DVT (Controls). Clinical information including age at diagnosis, type of cancer and chemotherapy were collected. Genotyping of blood group was done by single nucleotide polymorphisms analysis.

RESULTS

218 subjects were recruited at 4 Canadian pediatric centers. Multivariable analysis demonstrated 3 significant variables (reported as Odds Ratio (OR), (95% CI), p value): age at diagnosis p<0.001, non-O blood group OR 2.6 (1.3-5.2) p=0.005 and asparaginase treatment OR 2.4 (1.2-4.8) p=0.011. In order to optimise clinical utility, we reanalysed the study data with age at diagnosis categorised into four subgroups 0-≤2years, >2-≤7years, >7≤10years, >10years. A significant association with DVT were seen in children 0-≤2years (OR 3.1 (1.1-8.3) p=0.026) and >10years (OR 3.8, 1.7-8.5 p=0.001). Significant associations with DVT remained for non-O blood group, OR 2.2 (1.2-4.4) p=0.016 and asparaginase treatment, OR 2.1 (1.1-4.0) p=0.027. The value for the clinical risk model receiver operating characteristics curve was 0.67.

CONCLUSIONS

We have shown 3 independent risk factors for DVT in childhood cancer.

Haemostatic alterations induced by treatment with asparaginases and clinical consequences

The benefit of asparaginase for treating acute lymphoid leukaemia (ALL) has been well established. Native asparaginase derives from Escherichia coli (colaspase) or Erwinia chrysanthemi (crisantaspase); in a third preparation, colaspase is pegylated. Depletion of asparagine leads to decreased synthesis of procoagulant, anticoagulant, and fibrinolytic proteins, with resultant hypercoagulability and greater risk of venous thromboembolism (VTE). Colaspase and crisantaspase are not dose-equivalent, with crisantaspase displaying haemostatic toxicity only at dosages much higher and administered more frequently than those of colaspase. Cerebral venous thrombosis and pulmonary embolism are two life-endangering manifestations that occur during treatment with asparaginase particularly in children and in adults with ALL, respectively. Approximately one-third of VTEs are located in the upper extremities and are central venous line-related. Other risk factors are longer duration of asparaginase treatment and concomitant use of prednisone, anthracyclines, and oral contraceptives. The risk associated with inherited thrombophilia is uncertain but is clearly enhanced by other risk factors or by the use of prednisone. VTE prevention with fresh frozen plasma is not recommended; the efficacy of antithrombin (AT) concentrates has occasionally been reported, but these reports should be confirmed by proper studies, and AT should not be routinely employed. Therapeutic or prophylactic heparin doses are only partially effective, and direct thrombin or factor Xa inhibitors could play significant roles in the near future.

Venous thromboembolism in children with cancer - a population-based cohort study

Introduction

Cancer is a known risk factor for venous thromboembolism (VTE) in adults, but population-based data in children are scarce.

Materials and methods

We conducted a cohort study utilising linkage of the Clinical Practice Research Database (primary care), Hospital Episodes Statistics (secondary care), UK Cancer Registry data and Office for National Statistics cause of death data. From these databases, we selected 498 children with cancer diagnosed between 1997 and 2006 and 20,810 controls without cancer. We calculated VTE incidence rates in children with cancer vs. controls, and hazard ratios (HRs) using Cox regression.

Results

We identified four VTE events in children with cancer compared with four events in the larger control population corresponding to absolute risks of 1.52 and 0.06 per 1000 person-years respectively. The four children with VTE and cancer were diagnosed with hematological, bone or non-specified cancer. Childhood cancer was hence associated with a highly increased risk of VTE (HR adjusted for age and sex: 28.3; 95%CI = 7.0-114.5).

Conclusions

Children with cancer are at increased relative risk of VTE compared to those without cancer. Physicians could consider thromboprophylaxis in children with cancer to reduce their excess risk of VTE however the absolute risk is extremely small and the benefit gained therefore would need to be balanced against the risk invoked of implementing such a strategy.

Novelty & Impact Statements

While there is a reasonable level of knowledge about the risk of VTE in adult populations, it is not well known whether this risk is reflected in paediatric patients. We found a substantial increase in risk of VTE in children with cancer compared to a child population without cancer. While this finding is important, the absolute risk of VTE is still low and must be balanced with the risks of anticoagulation.

Dosing and monitoring of enoxaparin therapy in children: experience in a tertiary care hospital

Pediatric deep vein thrombosis (DVT) is an emerging problem in tertiary care hospitals, recent reviews shows a rate of 40.2/10,000 admissions. Experts affirm that enoxaparin has become in the drug of choice for DVT therapy. Despite this, there is a little information regarding the optimal dose schedule for enoxaparin therapy in children and the therapeutic guidelines for enoxaparin use in children are extrapolated from adult guidelines. Monitoring by antifactor Xa (anti-Xa) measurement and target concentrations between 0.5-1 U/ml at 4-6 h postdose are recommended. This study was designed to analyse our experience in paediatric-specific dosage requirements for enoxaparin therapy. A retrospective study was performed with patients less than 16 years old, who were treated with enoxaparin for DVT and monitored by anti-Xa concentration, between January 2005 and March 2012. Demographic and clinical characteristics and outcomes were obtained. Fourteen patients were analyzed: boy/girl ratio, 8/4; median age, 3.5 months. Cerebral venous sinus thrombosis was the most common indication for therapy. All patients presented thrombosis risks factors. Dose increases were necessary only in patients less than 6 years old. Target anti-Xa concentrations were achieved in 12 (85%) patients. Children younger than 1 year required a higher dose of enoxaparin/kg (1.5-2.7 mg/kg per 12 h). Complete resolutions of DVT were registered in all cases. The mean number of dose increases was three and a median of 11 days to achieve target anti-Xa concentration. This study indicates that an initial higher enoxaparin dose may be necessary in neonates and infants, but other factors must be considered to improve management.

The evaluation of protein Z levels of children with acute lymphoblastic leukaemia during induction therapy

The objective of this study was to evaluate the protein Z levels of children with acute lymphoblastic leukaemia (ALL) during induction therapy. Although several studies investigated the association between steroid and L-asparaginase (L-ASP) administration and levels of coagulation proteins such as protein C, protein S and antithrombin in children with ALL, protein Z levels have not been examined in any study yet. Peripheral blood was drawn from the study group before chemotherapy (PZ0) at diagnosis, at 12th day (PZ1), 15th day (PZ2), 18th day (PZ3) and 21st day (PZ4) of treatment wherein L-ASP treatment is given along with steroid administration according to ALL BFM-1995 chemotherapy protocol. Plasma protein Z levels were measured by enzyme immunoassay method. Mean protein Z level at PZ0 was 1.628 ± 0.485 μg/ml in the study group and 1.672 ± 0.662 μg/ml in the control group. No statistical difference was observed. In the study group, there was a slight increase in protein Z levels between the PZ0 and PZ1 periods in which only steroid therapy was administered. Statistically significant decrease was observed between protein Z levels in PZ0-PZ4, PZ1-PZ2, PZ1-PZ3, PZ1-PZ4 and PZ3-PZ4 periods. During the induction treatment, symptomatic haemorrhage or thrombosis was not followed up in any patients. We demonstrated that children with ALL have similar protein Z values to those of the control group at diagnosis. A significant decrease occurs at the end of the induction treatment with steroid and L-ASP administration. However, this deficiency does not result in development of symptomatic thrombosis or bleeding in these patients.

Pediatric venous thromboembolism in the United States: a tertiary care complication of chronic diseases

BACKGROUND

Pediatric venous thromboembolism (VTE) is an increasingly common problem. We hypothesized that VTE occurs most commonly in tertiary care settings and that the pattern of associated illnesses may have changed from earlier reports.

METHODS

The Kids' Inpatient Database 2006 was utilized to identify children ≤ 18 years old with in-hospital VTE. Children were identified by the presence of thrombosis specific ICD-9-CM diagnosis or procedure codes. Remaining ICD-9-CM codes were utilized to categorize patients by acute or chronic illness. The incidence of in-hospital VTE by hospital type, age, gender, race, and disposition were estimated.

RESULTS

Over 4,500 children met the inclusion criteria (188/100,000 discharges). Most VTE discharges (67.5%) were from children's hospitals (RR 5.09; 95% CI 4.76; 5.44). Underlying chronic illnesses were associated with most VTE (76.2%), most commonly: cardiovascular (18.4%), malignancy (15.7%), and neuromuscular disease (9.9%). VTE not associated with chronic illness were most often idiopathic (12.6%), followed by infections (9.5%), and trauma (9.1%). The greatest proportions of children with VTE were infants (23.1%) and adolescents (37.8%). However, when standardized against the entire database of discharges, infants were least likely to develop VTE (RR 0.48; 95% CI 0.43; 0.52), while adolescents were at highest risk (RR 1.89; 95% CI 1.73; 2.07). Hospitalizations ending with death were more likely to include VTE (RR 6.16; 95% CI 5.32; 7.13).

CONCLUSIONS

Pediatric VTE is most commonly seen in tertiary care. Adolescents are at greatest risk to develop in-hospital VTE. Patients whose hospitalization ended with death are at much greater risk to develop VTE.

Do children with central venous line (CVL) dysfunction have increased risk of symptomatic thromboembolism compared to those without CVL-dysfunction, while on cancer therapy?

Background

Thromboembolism (TE) and infection are two common complications of central venous line (CVL). Thrombotic CVL-dysfunction is a common, yet less studied, complication of CVL. Two retrospective studies have reported significant association of CVL-dysfunction and TE. Recent studies indicate association of CVL-related small clot with infection. Infection is the most common cause of non-cancer related mortality in children with cancer. We and others have shown reduced overall survival (OS) in children with cancer and CVL-dysfunction compared to those without CVL-dysfunction. Despite these observations, to date there are no prospective studies to evaluate the clinical significance of CVL-dysfunction and it’s impact on the development of TE, infection, or outcome of children with cancer.

Study design

This is a prospective, analytical cohort study conducted at five tertiary care pediatric oncology centers in Ontario. Children (≤ 18 years of age) with non-central nervous system cancers and CVL will be eligible for the study. Primary outcome measure is symptomatic TE and secondary outcomes are infection, recurrence of cancer and death due to any cause. Data will be analyzed using regression analyses.

Discussion

The overall objective is to delineate the relationship between CVL-dysfunction, infection and TE. The primary aim is to evaluate the role of CVL-dysfunction as a predictor of symptomatic TE in children with cancer. We hypothesize that children with CVL-dysfunction have activation of the coagulation system resulting in an increased risk of symptomatic TE. The secondary aims are to study the impact of CVL-dysfunction on the rate of infection and the survival [OS and event free survival (EFS)] of children with cancer. We postulate that patients with CVL-dysfunction have an occult CVL-related clot which acts as a microbial focus with resultant increased risk of infection. Further, CVL-dysfunction by itself or in combination with associated complications may cause therapy delays resulting in adverse outcome.

This study will help to identify children at high risk for TE and infection. Based on the study results, we will design randomized controlled trials of prophylactic anticoagulant therapy to reduce the incidence of TE and infection. This in turn will help to improve the outcome in children with cancer.

Thrombosis risk factor assessment and implications for prevention in critically ill children

OBJECTIVES

To describe nursing compliance with a computer-based pediatric thrombosis risk assessment tool; to generate an estimate of risk factors present in our population; and to explore relationships between risk factors and confirmed thrombotic events.

DESIGN

Institutional review board-approved prospective, observational cohort study.

SETTING

Pediatric intensive care unit within a tertiary care children's hospital.

PATIENTS

All infants and children admitted to the pediatric intensive care unit during a 6-month study period (January 1, 2010-June 30, 2010).

MEASUREMENTS AND MAIN RESULTS

Eight hundred admissions were enrolled, representing 742 patients. Thrombosis risk assessment scores were recorded for 707 admissions (88% of total). Mean age = 6.95 ± 6 yrs, mean weight = 28 ± 23 kg, 45% female. A total of 32 thrombi (14 prehospital and 18 in-hospital) were present in the study group. This translated to an overall occurrence rate of 4.3% (1.9% for prehospital and 2.4% for in-hospital). Logistic regression identified that for every 1-point increase in total thrombosis score, the risk of developing a symptomatic thrombus increased by 1.57-fold (95% confidence interval 0.192-5.5) to 2.12-fold (95% confidence interval 0.175-18.34), for prehospital and in-hospital thrombi, respectively (p < .05). The most important risk factors identified for development of any thrombus were thrombophilia (acquired or inherited) (p < .001), presence of a central catheter (p = .01), and age <1 or >14 yrs (p = .052).

CONCLUSIONS

Incorporation of a scoring system into the bedside nursing assessment flow sheet was successful and identified children at risk for in-hospital thrombosis. The overall score appears to be most indicative of thrombus risk. These data may serve as a platform for future development of routine screening and possible interventional trials in critically ill children.

The persistent thrombus: complications, diagnosis, and novel treatment intervention

OBJECTIVE

To review the findings and discuss the implications of the topic of pharmacomechanical thrombolysis in pediatric patients with persistent thrombus.

DESIGN

A pediatric case presentation with a brief literature review on treatment of venous thrombosis and pharmacomechanical thrombolysis.

INTERVENTIONS

None.

MAIN RESULTS

Thrombotic events refractory to standard medical and surgical care remain a life-threatening clinical challenge in the pediatric population. Research on persistent deep venous thrombosis and treatment modalities is limited. We present a pediatric patient with a history of malignant osteosarcoma who was diagnosed with deep venous thrombosis. Despite appropriate anticoagulation therapy, the thrombus remained persistent. Pharmacomechanical thrombolysis was utilized and proved to be an effective method in providing diagnosis and treatment.

CONCLUSION

Pharmacomechanical thrombolysis is a valuable and effective method in providing diagnosis and treatment of persistent thrombus.

Inherited Prothrombotic Risk Factors in Turkish Children With Acute Lymphoblastic Leukemia

Our study was designed to prospectively evaluate the role of the methylenetetrahydrofolate reductase (MTHFR) TT677 genotype, the prothrombin (PT) 620210A mutation, the factor V G1691A mutation in leukemic Turkish children treated according to modified BFM 95 study protocols with respect to the onset at thromboembolic events. Eighty-two consecutive leukemic children investigated had are established inherited prothrombotic risk factor: 29 children showed the MTHFR genotype (heterozygous, n = 22; homozygous, n = 7); 3 showed the heterozygous PT G20210A variant; 16 were carriers of the factor V mutation (heterozygous). In addition, combined prothrombotic defects were found in a further 11 patients the MTHFR mutation was combined with the F V mutation (n = 7), the PT G20210A variant (n = 2). In 7 (8.5%) of these 82 patients, venous thromboembolism occurred. In conclusion, the presence of inherited thrombophilia with Turkish children treated acute lymphoblastic leukemia may be useful for designing targeted primary prevention strategies.

Venous thromboembolism and adolescent and young adult oncology inpatients in US children's hospitals, 2001 to 2008

OBJECTIVES

To determine the frequency of venous thromboembolism (VTE) in the adolescent and young adult oncology population and the effects of age and cancer type on VTE, and to characterize adolescent and young adult oncology admissions at US children's hospitals.

STUDY DESIGN

We extracted data on oncology patients 15 to 24 years of age who were discharged from 35 hospitals in the Pediatric Hospital Information System (PHIS) between 2001 and 2008.

RESULTS

Of 9721 unique patients, VTE occurred in 511 (5.3%). An elevated OR of VTE occurred in patients 18 to 20 and 21 to 24 years of age (OR, 1.65; 95% CI, 1.36-2.00 and OR, 1.67; 95% CI, 1.21-2.32, respectively) compared with that in patients 15 to 17 years old. Patients with leukemia (OR, 5.53; 95% CI, 3.63-8.42) and bone/soft tissue sarcomas (OR, 4.32; 95% CI, 2.80-6.69) had a higher risk of VTE compared with patients with brain tumors. The number of adolescent and young adult oncology admissions to pediatric hospitals increased 31.9%, from 5409 admissions in 2001 to 7134 admissions in 2008.

CONCLUSIONS

Adolescent and young adult oncology patients, a growing population at pediatric hospitals, experience VTE as a common complication. Pediatricians should implement adolescent and young adult-specific studies to develop a standardized approach to preventing this adverse event.

An adolescent with lower-extremity swelling

Lower-extremity swelling is an uncommon presentation in a pediatric emergency department. Deep venous thrombosis is one of the common differential diagnoses in a patient with an underlying predisposing factor. We report a case of a previously healthy adolescent without any risk factor for thromboembolism presented with deep venous thrombosis. The pertinent literature is reviewed.

Mechanical compression versus subcutaneous heparin therapy in postoperative and posttrauma patients: a systematic review and meta-analysis

BACKGROUND

The risk of postoperative venous thromboembolic disease is as high as 30%, with an associated fatality risk of 1%. Therefore, prophylaxis is essential, but the optimal regimen remains controversial. This study was designed to systematically review and quantitatively summarize the impact of mechanical compression versus subcutaneous heparin on venous thromboembolic disease and posttreatment bleeding in postsurgical and posttrauma patients.

METHODS

Computerized searches of the MEDLINE and EMBASE databases through November 2008 were performed and supplemented with manual searches. We included studies that had: (1) a patient population undergoing surgery or admitted immediately posttrauma, (2) a randomized comparison of prophylaxis with mechanical compression versus subcutaneous heparin, (3) outcome measured in terms of deep vein thrombosis (DVT), pulmonary embolism (PE), or bleeding.

RESULTS

Two reviewers independently extracted data from the original articles, which represented 16 studies, including a total of 3,887 subjects. Meta-analysis was performed using a random effects model. The pooled relative risk for mechanical compression compared with subcutaneous heparin was 1.07 (95% confidence interval [CI] 0.72, 1.61) for DVT and 1.03 (95% CI 0.48, 2.22) for PE. Mechanical compression was associated with a significantly reduced risk of postoperative bleeding compared with subcutaneous heparin (risk ratio 0.47; 95% CI 0.31, 0.70). Subgroup analyses by heparin type suggested that low molecular weight heparin may reduce risk of DVT compared with compression (relative risk 1.80; 95% CI 1.16, 2.79) but remains similarly associated with an increased risk of bleeding.

CONCLUSIONS

These results suggest that the overall bleeding risk profile favors the use of compression over heparin, with the benefits in term of venous thromboembolic disease prophylaxis being similar between groups. Subgroup analyses suggest that low molecular weight heparin may have a differential effect; this observation should be further evaluated in future studies.

Validation of a predictive model for identifying an increased risk for thromboembolism in children with acute lymphoblastic leukemia: results of a multicenter cohort study

Among risk factors for developing thromboembolism (VTE) in children with acute lymphoblastic leukemia were Escherichia coli asparaginase, concomitant steroid use, presence of central venous lines, and thrombophilic abnormalities. Developing a predictive model for determining children at increased risk would be beneficial in targeting interventional studies to high-risk groups (HRGs). Predictive variables were incorporated into a risk assessment model, which was evaluated in 456 children and then validated in 339 patients. VTE risk by score was no greater than 2.5 for low-risk group (LRG) and greater than 2.5 for HRG. VTE rates at 3.5 months (validation cohorts) were 2.5% in LRG and 64.7% in HRG. In multivariate analysis adjusted for age, duration of asparaginase administration, enoxaparin prophylaxis, and T-immunophenotype, the HRG was significantly associated with VTE compared with the LRG (hazard/95% confidence interval [CI], 8.22/1.85-36.53). Model specificity was 96.2% and sensitivity was 63.2%. As secondary objective we investigated the use of enoxaparin for VTE prophylaxis in the HRG. HRG patients without enoxaparin prophylaxis showed a significantly reduced thrombosis-free survival compared with children on low-molecular-weight heparin (LMWH). On the basis of the high specificity, the model may identify children with leukemia at risk of VTE. LMWH may help prevent VTE in the HRG; this warrants assessment in larger cooperative clinical trials.

Thrombosis in childhood acute lymphoblastic leukaemia: epidemiology, aetiology, diagnosis, prevention and treatment

Acute lymphoblastic leukaemia (ALL) is the most common malignancy associated with venous thromboembolism (VTE) in children. The prevalence of symptomatic VTE ranges from 0% to 36%, and the variation can be explained, at least in part, by differences in chemotherapeutic protocols. The mechanism for increased risk of VTE is associated with alterations in the haemostatic system by use of L-asparaginase (ASP) alone or in combination with vincristine or prednisone, presence of central venous lines (CVLs) and/or inherited thrombophilia. The children at greatest risk are generally those receiving Escherichia coli ASP concomitant with prednisone. The majority of symptomatic VTEs occur in the central nervous system or in the upper venous system. In the majority of cases, asymptomatic VTEs are associated with CVLs. External CVLs are affected more often than internal CVLs. Evidence-based guidelines on prevention and treatment guidelines for ALL-related VTE are lacking, and carefully designed clinical trials are needed urgently.

Cerebral venous sinus thrombosis in an adolescent with Ewing sarcoma

BACKGROUND

Although thromboembolic complications are common in adult patients with malignant diseases, cerebral venous sinus thrombosis has been rarely described in cancer afflicted pediatric and adolescent population.

CASE HISTORY

A 16-year-old adolescent girl referred for complaints of pain and swelling on her left leg. On physical examination, a solid tibial mass was discovered. After the diagnosis of Ewing sarcoma with a tru-cut biopsy, chemotherapy protocol consisting of cisplatin, ifosfamide, adriamycine, and vincristine was started. During the first course of the treatment, the patient expressed headache, diplopia, and ptosis. Contrast-enhanced magnetic resonance (MR) images and MR angiography showed superior sagittal and transverse sinus thromboses. After anticoagulant therapy, the thromboses disappeared within 1.5 months. She received her chemotherapy protocol with the anticoagulant prophylaxis. After a follow-up period of 12 months, she is still in a good neurological recovery without any sequel.

CONCLUSION

Children and adolescents with cancer should be monitored closely for thrombotic complications. We discuss this uncommon case to draw attention to the importance of early diagnosis and adequate treatment of intracranial thrombosis in childhood cancer, and we review the relevant literature.

Determination of risk factors for deep venous thrombosis in hospitalized children

PURPOSE

Our objective was to determine the time trend and risk factors for deep venous thrombosis (DVT) of the lower extremities among pediatric inpatients.

METHODS

This cross-sectional study used the data from the Health Care Cost and Utilization Project Kids' Inpatient Database for the years of 1997, 2000, and 2003 to estimate the DVT prevalence and crude and adjusted prevalence ratios. Patients between the ages of 1 and 17 years and who were hospitalized for at least 4 days were included.

RESULTS

The weighted prevalence of DVT was 4.2 per 1000 hospital discharges (95% confidence interval [CI], 3.4-3.7). Independent of age, the prevalence of DVT was significantly greater in 2000 and 2003 compared to 1997, prevalence ratio (PR) of 1.2 and 1.4 (95% CI, 1.1-1.3 and 1.2-1.4). Using only the 2003 database, adjusted analysis revealed that patients at highest risk were those in the age range of 15 to 17 years (PR, 2.0; 95% CI, 1.6-2.4) and with the following comorbid conditions: obesity (PR, 2.1; 95% CI, 1.5-2.8), inflammatory bowel disease (PR, 1.8; 95% CI, 1.2-2.7), hematologic malignancy (PR, 2.5; 95% CI, 2.0-3.1), and thoracoabdominal (PR, 1.8; 95% CI, 1.6-2.2) or orthopedic (PR, 2.2; 95% CI, 1.7-2.8) operations. Predictors not associated with DVT included sex and diagnosis of trauma.

CONCLUSIONS

The discharge diagnosis of DVT of the lower extremities has significantly increased since 1997. In addition, teenagers with underlying disorders are at highest risk for DVT.

Granulomatous reaction in mediastinal B-cell non-Hodgkin lymphoma and intracardiac thrombosis

Epithelioid cell granulomas may be associated with several neoplasms. Lymphomas may mimic or are associated with epithelioid granulomas. In this article the authors report a child with granulomatous reaction in B cell non-Hodgkin lymphoma and intracardiac thrombosis. Although cancer alone is a risk factor for thromboembolism, thrombosis is a multifactorial disorder with both hereditary and acquired risk factors. This is the first reported case of intracardiac thrombosis with MTHFR A1298C and factor XIII V34L mutations together with granulomatous reaction in non-Hodgkin lymphoma.

Tourniquet use in childhood: a harmless procedure?

Tourniquet ischemia is widely used in limb surgery in every age group. In adults, tourniquet-related deep vein thrombosis and pulmonary embolism are recognized complications of tourniquet use. In healthy children, tourniquet-associated alterations of blood clotting physiology are assumed to have no clinical impact. Antithrombotic prophylaxis is, therefore, recommended only in the presence of pertinent risk factors such as extensive surgery, congenital thrombophilia, prolonged immobilization, and indwelling central venous line, however, it is not practiced in obese, otherwise healthy children. We describe the first case of fatal pulmonary thromboembolism in an obese 12-year and 3-month old boy (body mass index 27.6 kg x m(-2)) following tourniquet-deflation after minor surgery on the lower extremity.