Epidemiology and Risk Assessment of Pediatric Venous Thromboembolism

Risk of Venous Thromboembolism in Adolescents Undergoing Pelvic Osteotomy: Insights From a Propensity-matched Retrospective Cohort Study

BACKGROUND

Pelvic osteotomies are surgical procedures that are commonly performed in adolescents and young adults to improve stability or correct various deformities. Venous thromboembolism (VTE), including pulmonary embolism (PE) and deep vein thrombosis (DVT), are dreaded complications of any major procedure including pelvic osteotomies. Unlike adults, the incidence of DVT and need for prophylactic measures are not well understood in the adolescents. The purpose of this study is to understand the need for VTE prophylaxis in adolescents and determine if their risk profile aligns with adults, who have more established VTE prophylactic guidelines in place for these surgeries.

METHODS

This retrospective cohort study utilized data from the TriNetX Research Network, which includes records from over 80 healthcare organizations and more than 120 million patients. De-identified patient data from January 1, 2003, to March 1, 2024, were extracted using relevant ICD-9 and ICD-10 procedural codes. The study included 2 cohorts: patients aged 13 to 17 years (adolescents) and patients 18 years and older (adults) who underwent pelvic osteotomies. To control for confounding variables, propensity score matching was employed based on sex and relevant comorbidities, including diabetes mellitus, tobacco use, and overweight/obesity. Statistical significance was set at P<0.01.

RESULTS

A total of 2374 patients successfully matched in each cohort. Within 90 days following surgical intervention, adult patients had overall risks of 4.5%, 1.9%, and 5.9%, whereas adolescent patients had overall risks of 1.3%, 0.5%, and 1.4% for DVT (RR: 3.419), PE (RR: 4.182), and either DVT or PE (RR: 4.118), respectively.

CONCLUSIONS

This study examines the rate of VTE in a large cohort of adolescents undergoing pelvic osteotomies. Although we found the rates to be lower in adolescents compared with adults, the high absolute risk in adolescents-above 1%, the threshold established in the literature for considering prophylaxis-underscores the need for tailored risk stratification strategies and targeted thromboprophylaxis protocols for this population.

LEVELS OF EVIDENCE

Level III: case-control study or retrospective cohort study.

Retrospective study evaluating safety, clinical effect, and dosing of dalteparin for the treatment of venous thromboembolism in term neonates

BACKGROUND

There is an increased risk of venous thromboembolism (VTE) among neonates due to their unique hemostatic system. However, there is lack of approved treatment options for VTE in neonatal population. Importantly, dalteparin, a low molecular weight heparin approved for pediatric VTE in children ≥1 month of age, has also been used for the treatment of neonatal VTE. Based on the request from the Food and Drug Administration, this retrospective study aimed to characterize the safety, clinical effects, and dosing of dalteparin for treatment of VTE among neonates.

PROCEDURE

Data from electronic medical records for neonates (born ≥35 weeks of gestation) treated with dalteparin for VTE between January 2010 and December 2021 were collected. The data assessed included bleeding and deterioration in hematological biomarkers among other adverse events, changes in relevant factor antifactor Xa (anti-Xa) levels and VTE status, and dosing of dalteparin and corresponding anti-Xa assay levels.

RESULTS

Sixteen neonates from five participating sites in the United Kingdom were included. There were no bleeding events or deaths. Only one serious adverse event of hypoglycemic brain injury (unrelated to dalteparin) was documented in a patient with a history of hyperinsulinism. Median (range) daily dose of dalteparin at initiation was 309 (297-314) IU/kg. Eight of 16 neonates achieved therapeutic anti-Xa level, including two patients who did so after the first dose.

CONCLUSIONS

Dalteparin treatment in neonates raised no major safety concerns. Larger cohort studies may help provide further insights on clinical effects of dalteparin for neonatal VTE.

Hospital acquired venous thromboembolism in children with sickle cell disease

Sickle cell disease (SCD) is well recognized as a hypercoagulablestate, however, it remains unclear whether a subgroup of children with SCD at higher risk of venous thromboembolic event (VTE) during hospitalization may benefit from thromboprophylaxis. Our objectives were to describe the clinical characteristics, outcomes and recurrence of hospital acquired VTE in patients with SCD younger than 21 years. This was a single center retrospective study. Data regarding demographics, reason for admission, location of VTE, risk factors like central venous catheter (CVC), intensive care unit (ICU) admission among others were extracted from electronic medical records over a 10-year study period (2011-2021). Recurrence of VTE at 1 and 5 years was assessed. Descriptive statistics were used as indicated. We identified a total of 20 VTE events over the 10-year study period. Six of these events occurred in those younger than 12 years of age. Fourteen (70%) VTE events occurred in the HbSS or HbSβThal0 genotypes compared to 6 (30%) in HbSC. Most common VTE was isolated pulmonary embolism (PE) (n = 10, 50%). VTE were most often associated with acute chest syndrome (ACS) (n = 14, 70%), ICU admissions (n = 10, 50%) and CVC (n = 5/9, 55%). One patient died from the VTE event. One patient with additional underlying risk factors had a recurrent VTE at 13 months. Our study suggests that ICU admission, ACS and presence of CVC increases the risk of VTE in children and young adults with SCD, but larger studies are indicated to validate our findings.

Enoxaparin thromboprophylaxis in hospitalized obese pediatric patients

BACKGROUND

Enoxaparin is an anticoagulant used for pharmacologic thromboprophylaxis in pediatrics. Enoxaparin pharmacokinetics can be altered in the setting of obesity. Optimal enoxaparin dosing for thromboprophylaxis in children with obesity remains unclear.

PROCEDURE

A retrospective review was conducted of pediatric patients who weighed ≥60 kg with BMI ≥ 95th percentile, received enoxaparin for thromboprophylaxis, and had at least one appropriately drawn anti-factor Xa (anti-Xa) from 2013 to 2022. Anti-Xa levels were reviewed for patients initially treated with enoxaparin 30 mg every 12 h. The average daily enoxaparin dose required to achieve an anti-Xa of 0.2-0.4 unit/mL, which was stratified by BMI percentile and weight, was calculated.

RESULTS

Of 116 patients (median age 15.8 years) included for analysis, 106 patients were initially treated with enoxaparin 30 mg every 12 h. Anti-Xa levels were <0.2 unit/mL in 53% of patients with BMI > 99th percentile and 54% of patients >100 kg. Ninety-one patients had at least one anti-Xa 0.2-0.4 unit/mL with an average daily enoxaparin dosing of 66 mg. When stratified by severity of obesity, higher doses were required to attain an anti-Xa 0.2-0.4 unit/mL in patients with BMI > 99th percentile compared with those with 95th-99th percentile (67.8 ± 15.7 vs. 62 ± 5.6 mg/day, p = .01). Patients > 100 kg required significantly higher dose than those ≤100 kg (69.1 ± 15.5 vs 61.2 ± 7.3 mg/day, p = .002).

CONCLUSIONS

Increased initial dosing and/or anti-Xa level monitoring should be considered in adolescents with severe obesity receiving enoxaparin thromboprophylaxis.

Selective iliofemoral stent placement for complex pediatric cases: a decade of institutional experience

BACKGROUND

Pediatric iliofemoral venous thromboembolism that is resistant to conventional treatments poses significant management challenges. Stent placement represents a potentially underutilized strategy in children when stenosis or thrombosis persists intraprocedurally or recurs postoperatively, despite treatments such as venoplasty, lysis, and thrombectomy.

OBJECTIVE

This study aims to report our institutional experience with iliofemoral stenting in 17 pediatric patients with recurrent iliofemoral venous thromboembolism or stenosis.

MATERIALS AND METHODS

We performed an IRB-approved retrospective review of pediatric patients (<18 years of age) who underwent iliofemoral venous stenting for recurrent stenosis or thrombosis between January 2012 and December 2022 at a single tertiary care institution. Patient demographics, risk factors for venous thromboembolism, presenting symptoms, and procedural characteristics were recorded. The primary outcome was stent patency rates at interval imaging follow-up.

RESULTS

Seventeen patients with mean age of 14.6 years (range 7-17) and mean BMI of 27.7 were stented during the study period. Sixteen of 17 patients presented with evidence of May-Thurner anatomy. 14/17 patients presented with acute iliofemoral venous thromboembolism, 2/17 with chronic venous thromboembolism, and 1/17 with left lower extremity swelling without thrombosis. Seventy-three total angiographic procedures were performed, which included angioplasty, lysis, and thrombectomy, and 23 stent placements. Patients underwent an average of 3 procedures (range 1-9) over a mean of 2.8 months (range 0-17 months) prior to undergoing stent placement. Stents were deployed successfully in all patients. The median follow-up was 18 months (range, 1-77 months). Primary and secondary patency rates were 13/17 (76%) and 14/14 (100%) at 12 months and 12/17 (71%) and 14/14 (100%) at 24 months, respectively.

CONCLUSION

In our experience of 17 patients, stent placement appears to be a durable option for children with iliofemoral venous thromboembolism following failure to establish vessel patency or development of recurrent thrombosis/stenosis postoperatively.

Percutaneous Image-Guided Treatment of Pediatric Deep-Vein Occlusions

Pediatric venous occlusions are a growing cause of morbidity and mortality, especially in hospitalized patients. Catheter-directed recanalization is a safe and effective treatment option in appropriately selected patients. Benefits of catheter directed therapies (CDTs) include the prevention of pulmonary embolism and end organ failure acutely as well as superior vena cava syndrome and post-thrombotic syndrome chronically. Timely diagnosis, recognition of underlying factors for thrombosis, and familiarity with the spectrum of tools and techniques for CDT are essential to optimizing outcomes in the acute setting. Recanalization of chronic venous occlusions can similarly provide symptomatic relief and achieve long term vessel patency. This review will detail the scope, techniques, and outcomes for CDT in the treatment of acquired systemic deep vein occlusions.

Risk factors for venous thromboembolism in a single pediatric intensive care unit in China

BACKGROUND

Analyses of extensive, nationally representative databases indicate a rising prevalence of venous thromboembolism (VTE) among critically ill children. However, the majority of studies on childhood VTE have primarily concentrated on Caucasian populations in the United States and European countries. There is a lack of epidemiological studies on VTE in Chinese children.

METHODS

We conducted a retrospective cohort study of data from the Pediatric Intensive Care (PIC) database. Data were obtained and extracted by using Structured Query Language (SQL) and the administrative platform pgAdmin4 for PostgreSQL. Bivariate analyses were conducted in which categorical variables were analyzed by a chi-square test and continuous variables were analyzed by a Student's t-test. Separate multivariable logistic regressions were employed to investigate the associations between VTE and sociodemographic factors as well as clinical factors.

RESULTS

Our study included 12,881 pediatric patients from the PIC database, spanning the years 2010 to 2018. The incidence rate of pediatric VTE was 0.19% (24/12,881). The venous thrombotic locations were deep venous thrombosis extremities (n = 18), superior vena cava (n = 1), cerebral sinovenous (n = 1), and other deep venous thrombosis (n = 4). Univariate analysis showed that age, weight, shock, sepsis, cancer and vasopressor receipt were statistically significant risk factors for pediatric VTE (all p ≤ 0.05). After multivariable logistic regression analysis, only shock (aOR: 6.77, 95%CI: 1.33-34.73, p = 0.019) and admission for sepsis (aOR: 6.09, 95%CI: 1.76-21.09, p = 0.004) were statistically significant associated with pediatric VTE.

CONCLUSIONS

In conclusion, data obtained from the Pediatric Intensive Care (PIC) database revealed a prevalence of VTE in pediatric patients of 0.19%. The most common location for venous thrombi was deep venous thrombosis (DVT) in the extremities. We identified that shock and sepsis were statistically significant factors associated with pediatric VTE.

Optimization of Thromboprophylaxis Use in Hospitalized Pediatric Patients Through Implementation of a Venous Thromboembolism Risk Assessment Tool

OBJECTIVE

Venous thromboembolism (VTE) is a leading cause of hospital-acquired morbidity for pediatric patients. Pharmacological thromboprophylaxis increases the risk of adverse events such as bleeding complications. There exists a need for a universal VTE risk assessment tool to aid in thromboprophylaxis prescribing while minimizing the risk of adverse events. The objective of this study is to investigate if implementation of a VTE risk assessment tool is associated with a change in the rate of thromboprophylaxis prescribing.

METHODS

This retrospective study evaluated the change in thromboprophylaxis prescribing pre and post implementation of a VTE risk assessment tool. Patients were excluded if they were pregnant, diagnosed with VTE ≤48 hours of admission, presented with VTE symptoms, or if they were diagnosed with multisystem inflammatory syndrome in children (MIS-C) or coronavirus disease (COVID-19).

RESULTS

A total of 186 pediatric patients were included in this study. Thromboprophylaxis was prescribed in 16/93 (17.12%) and 75/93 (80.6%) patients in the pre- and post-implementation group, respectively (95% CI, 0.523-0.745; p < 0.001). No VTE events occurred in either group. Bleeding complications occurred in 3.2% and 7.5% of patients in the pre- and post-implementation groups, respectively. The risk tool was used in 80.6% of patients; providers used the tool correctly in 48% of patients and incorrectly in 52% of patients.

CONCLUSION

Implementation of a VTE risk assessment tool was associated with a statistically significant change in the rate of thromboprophylaxis prescribing. Incorrect use may be minimized by providing provider reeducation and making modifications to the order set.

Model-Guided Decision-Making for Thromboprophylaxis and Hospital-Acquired Thromboembolic Events Among Hospitalized Children and Adolescents: The CLOT Randomized Clinical Trial

Importance

Rates of hospital-acquired venous thromboembolism (HA-VTE) are increasing among pediatric patients. Identifying at-risk patients for whom prophylactic interventions should be considered remains challenging.

Objective

To determine whether use of a previously validated HA-VTE prognostic model, together with pediatric hematologist review, could reduce pediatric inpatient rates of HA-VTE.

Design, Setting, and Participants

This pragmatic randomized clinical trial was performed from November 2, 2020, through January 31, 2022, at a single-center academic children's hospital (Monroe Carell Jr Children's Hospital at Vanderbilt). All pediatric hospital admissions (aged <22 years) under inpatient status were included and randomized.

Intervention

All patients had an HA-VTE probability automatically calculated daily, which was visible to the hematology research team for patients in the intervention group. Patients with an elevated risk (predicted probability ≥2.5%) underwent additional medical record review by the research team to determine eligibility for thromboprophylaxis.

Main Outcomes and Measures

The primary outcome was rate of HA-VTE. Secondary outcomes included rates of prophylactic anticoagulation and anticoagulation-associated bleeding events.

Results

A total of 17 427 hospitalizations met eligibility criteria, were randomized, and were included in the primary analysis: patients had a median (IQR) age of 1.7 (0 to 11.1) years; there were 9143 (52.5%) female patients and 8284 (47.5%) male patients, and there were 445 (2.6%) Asian patients, 2739 (15.9%) Black patients, and 11 752 (67.4%) White patients. The 2 groups were evenly balanced in number (8717 in the intervention group and 8710 in the control group) and patient characteristics. A total of 58 patients (0.7%) in the control group and 77 (0.9%) in the intervention group developed HA-VTE (risk difference: 2.2 per 1000 patients; 95% CI, -0.4 to 4.8 per 1000 patients; P = .10). Recommendations to initiate thromboprophylaxis were accepted by primary clinical teams 25.8% of the time (74 of 287 hospitalizations). Minor bleeding events were rare among patients who received anticoagulation (3 of 74 [4.1%]), and no major bleeding events were observed during the study period. Among patients randomized to the control group, the model exhibited high discrimination accuracy (C statistic, 0.799, 95% CI, 0.725 to 0.856).

Conclusions and Relevance

In this randomized clinical trial of the use of a HA-VTE prognostic model to reduce pediatric inpatient rates of HA-VTE, despite the use of an accurate and validated prognostic model for HA-VTE, there was substantial reluctance by primary clinical teams to initiate thromboprophylaxis as recommended. In this context, rates of HA-VTE between the control and intervention groups were not different. Future research is needed to identify improved strategies for prevention of HA-VTE and to overcome clinician concerns regarding thromboprophylaxis.

Trial Registration

ClinicalTrials.gov Identifier: NCT04574895.

Deep Vein Thrombosis after a Supracondylar Fracture of the Humerus in a Child - A Rare Complication

Deep vein thrombosis in the upper extremities is uncommon, especially in the pediatric population and in the trauma setting. The diagnosis is challenging, due to its rarity, requiring a high degree of suspicion. We describe a rare case of humeral vein thrombosis after a displaced supracondylar fracture of the humerus in a 7-year-old girl. The risk factors for thromboembolism and sequelae are also discussed. The early detection and treatment are mandatory to prevent poor outcomes, such as fatal thromboembolism.

Risk Factors for Venous Thromboembolic Events in Children With Acute Musculoskeletal Infections

BACKGROUND AND OBJECTIVES

Venous thromboembolic events (VTE) complicate acute hematogenous musculoskeletal infections (MSKIs) among hospitalized children. However, there is limited guidance for which specific MSKI patients are at the greatest VTE risk. This study aimed to identify VTE risk factors for children hospitalized with MSKIs.

METHODS

A retrospective chart review was performed of children hospitalized with MSKIs at a single quaternary care pediatric hospital during a 9-year period. Patients with chronic MSKIs, non-hematogenous infections, or significant contributing comorbidities were excluded. Demographic and clinical characteristics were compared between patients with and without VTE using forward stepwise conditional multivariable logistic regression to identify VTE risk factors.

RESULTS

Among 335 included patients, 7 (2.1%) developed a VTE. There was no difference in age, sex, or obesity rates for those with or without VTE. Patients with methicillin-resistant Staphylococcus aureus (MRSA) infections and/or critical illness were more likely to develop a VTE with summative adjusted odds ratios of 31.7 and 26.4, respectively. In addition, patients with VTEs had longer hospitalizations (median 4.7 vs. 12.8 d, P <0.001), longer courses of intravenous antimicrobials (median 3.7 vs. 13.5 d, P =0.001), and longer time to fever resolution (median 25.7 vs. 162 h, P =0.004).

CONCLUSIONS

VTE prevalence among children with acute MSKIs is low. MRSA infection and critical illness significantly increase the risk for VTE development in these patients. Future prospective studies are needed to determine if VTEs in high-risk MSKI patients can be prevented.

Management of venous thromboembolism in pediatric patients: Quality assessment of clinical practice guidelines and variations in recommendations

INTRODUCTION

We performed a quality assessment and comparison of clinical practice guidelines (CPGs) for the prevention and treatment of venous thromboembolism (VTE) in pediatric patients and to provide a clinical reference.

MATERIALS AND METHODS

Electronic databases, guideline development organizations, and professional societies were searched to identify CPGs for VTE in pediatric patients between January 1, 2012, and April 7, 2022. The Appraisal of Guidelines Research & Evaluation (AGREE) II instrument was used to evaluate quality. Recommendations for preventing and treating VTE in pediatric patients were extracted via descriptive synthesis.

RESULTS

Six CPGs were included. The median scores (interquartile range [IQR]) for each AGREE II domain were as follows: scope and purpose, 88.89 % (IQR: 8.33 %); stakeholder involvement, 88.89 % (25 %); rigor of development, 67.71 % (24.47 %); clarity and presentation, 88.89 % (0 %); applicability, 50 % (42.71 %); and editorial independence, 66.67 % (50.00 %). In total, 268 key recommendations were extracted, and traditional anticoagulants (heparin and warfarin) remain the standard treatment. However, in recent years direct oral anticoagulants (DOACs) have shown similar efficacy and safety results for the treatment of VTE in children to those reported in adults; therefore, this practice is recommended in recent guidelines.

CONCLUSIONS

Variability exists in the development and reporting of CPGs for VTE in pediatric patients. There may be changes to the recommendations for the prevention and treatment of VTE in pediatrics in the future due to the efficacy of DOACs in children, and recommendations should be revised periodically as new evidence emerges.

Use of a real-time risk-prediction model to identify pediatric patients at risk for thromboembolic events: study protocol for the Children's Likelihood Of Thrombosis (CLOT) trial

BACKGROUND

Pediatric patients have increasing rates of hospital-associated venous thromboembolism (HA-VTE), and while several risk-prediction models have been developed, few are designed to assess all general pediatric patients, and none has been shown to improve patient outcomes when implemented in routine clinical care.

METHODS

The Children's Likelihood Of Thrombosis (CLOT) trial is an ongoing pragmatic randomized trial being conducted starting November 2, 2020, in the inpatient units at Monroe Carell Jr. Children's Hospital at Vanderbilt in Nashville, TN, USA. All admitted patients who are 21 years of age and younger are automatically enrolled in the trial and randomly assigned to receive either the current standard-of-care anticoagulation practice or the study intervention. Patients randomized to the intervention arm are assigned an HA-VTE risk probability that is calculated from a validated VTE risk-prediction model; the model is updated daily with the most recent clinical information. Patients in the intervention arm with elevated risk (predicted probability of HA-VTE ≥ 0.025) have an additional review of their clinical course by a team of dedicated hematologists, who make recommendations including pharmacologic prophylaxis with anticoagulation, if appropriate. The anticipated enrollment is approximately 15,000 patients. The primary outcome is the occurrence of HA-VTE. Secondary outcomes include initiation of anticoagulation, reasons for not initiating anticoagulation among patients for whom it was recommended, and adverse bleeding events. Subgroup analyses will be conducted among patients with elevated HA-VTE risk.

DISCUSSION

This ongoing pragmatic randomized trial will provide a prospective assessment of a pediatric risk-prediction tool used to identify hospitalized patients at elevated risk of developing HA-VTE.  TRIAL REGISTRATION: ClinicalTrials.gov NCT04574895. Registered on September 28, 2020. Date of first patient enrollment: November 2, 2020.

Current practices in pediatric hospital-acquired thromboembolism: Survey of the Children's Hospital Acquired Thrombosis (CHAT) Consortium

Background

A rise in hospital-acquired venous thromboembolism (HA-VTE) in children has led to increased awareness regarding VTE prophylaxis and risk assessment. Despite no consensus exists regarding these practices in pediatrics.

Objective

To describe common practices in VTE prophylaxis, VTE risk assessment models, and anticoagulation dosing strategies in pediatric hospitals that are members of the Children's Hospital Acquired Thrombosis (CHAT) Consortium.

Methods

An electronic survey of 44 questions evaluating practices surrounding pediatric HA-VTE risk assessment and prevention was distributed between August 9, 2021, and August 30, 2021, to the primary investigators from the 32 institutions within the CHAT Consortium.

Results

The survey response rate was 100% (n = 32). In total, 85% (n = 27) of the institutions assess HA-VTE, but only 63% (n = 20) have formal hospital guidelines. Within the institutions with formal guidelines, 100% (n = 20) include acute systemic inflammation or infection and presence of a central venous catheter (CVC) as risk factors for VTE. Pharmacologic prophylaxis is prescribed at 87% (28) of institutions, with enoxaparin being the most frequent (96%, n = 27). Variability in responses persisted regarding risk factors, risk assessment, thromboprophylaxis, dosing of prophylactic anticoagulation or anticoagulant drug monitoring. A majority of providers were comfortable providing thromboprophylaxis across all age groups. In addition, the global coronavirus disease 2019 increased the providers' use of prophylactic anticoagulation 78% (n = 25).

Conclusion

Practices among institutions are variable in regard to use of HA-VTE prophylaxis, risk assessment, or guideline implementation, highlighting the need for further research and a validated risk assessment model through groups like the CHAT Consortium.

Inherited and acquired causes renal vein thrombosis in an 11-year-old boy who was relieved after piperacillin-tazobactam and rivaroxaban treatment: a case report

BACKGROUND

Physiological hypercoagulability is a well-known condition in older populations, whereas thrombosis, especially in renal veins, is a rare occurrence in teenagers. This paper presents a pediatric case of renal venous infarction and thrombosis.

CASE DESCRIPTION

We report the case of an 11-year-old Chinese boy who presented with low back discomfort and was afraid to walk. Computed tomography (CT) revealed thrombosis in his renal veins and inferior vena cava. He was being treated for severe refractory mycoplasma pneumoniae pneumonia (MPP). He was treated with rivaroxaban and urokinase for thrombosis, and azithromycin for MPP. On day 2 after admission, his symptoms improved. Therefore, the dosage of rivaroxaban was decreased from 10 to 5 mg twice per day. On day 3 after admission, enhanced CT revealed new thromboses in the bilateral pulmonary trunks and arteries, inferior cava, right renal veins, bilateral common iliac veins, and internal iliac vein. The ultrasonography showed a strip hypoecho at the pulmonary artery bifurcation. All the above imaging suggested that antithrombotic therapy was insufficient. His plasma antithrombin (AT) III activity remained consistently low during hospitalization. The family history was re-examined and revealed that both his father and grandfather had experienced spontaneous pulmonary thrombosis around the age of 30. He was diagnosed with acquired and inherited thrombosis and inherited AT III deficiency. Following a medication regimen of piperacillin-tazobactam for 1 week and rivaroxaban (10 mg, twice daily), he was discharged and no thrombosis and other side effects or complications occurred in the following 3 months.

CONCLUSIONS

This is a rare case of a teenager with inherited and acquired hypercoagulability. For refractory MPP pediatric patients with thrombosis, clinicians should consider whether hereditary factors, such as inherited AT III deficiency, are involved in thrombosis.

Characteristics of Deep Venous Thrombosis in Isolated Lower Extremity Fractures and Unsolved Problems in Guidelines: A Review of Recent Literature

Deep venous thrombosis (DVT) has been characterized by a disorder of venous return caused by abnormal blood clotting in deep veins. It often occurs in the lower limbs and is a common complication in orthopaedics. Therefore, relevant professional organizations domestic and overseas had formulated and constantly updated relevant guidelines to prevent the occurrence of DVT. According to the management strategy of the guidelines, the incidence of DVT can be significantly reduced. However, due to the variety of fractures types, the guidelines cannot expound precautions and characteristics of DVT for all fracture types at present, and there are other related unresolved problems. For example, there is still a lack of consistent optimal strategies for the management of DVT following isolated lower extremity fractures with a higher incidence. The best anticoagulant strategies for patients with upper limb fractures, pediatric fractures, and those combined with other injuries are rarely described in orthopaedic guidelines, but such fractures are common in clinical orthopaedics. The long‐term complications after DVT, such as post‐thrombotic syndrome, are not well‐understood. In the absence of clear guidance, orthopaedic surgeons often resort to empiric anticoagulation or conservative treatment, so the prevention effects of DVT are inconsistent. The purpose of this review is to summarize the characteristics of DVT events after isolated lower extremity fractures and to discuss the unsolved issues in the guidelines by reviewing the previous literature and tracing the history of DVT discovery, to provide more scientific and comprehensive recommendations for the prediction and prevention of DVT.

Outcomes of Prophylactic Enoxaparin Against Venous Thromboembolism in Hospitalized Children

OBJECTIVES

To assess the biochemical and clinical outcomes of hospitalized children who received prophylactic enoxaparin.

METHODS

We conducted a retrospective observational study of hospitalized children aged <18 years who received prophylactic enoxaparin against hospital-acquired venous thromboembolism (HA-VTE). Weight-based enoxaparin dosing was administered using a pharmacy-driven protocol, which later included a low molecular weight, anti-Xa level directed-dose adjustment strategy. Primary biochemical and clinical outcomes were achievement of goal anti-Xa range of 0.2 to 0.5 IU/mL and development of HA-VTE, respectively. Secondary clinical outcome was development of clinically relevant bleed.

RESULTS

We analyzed 194 children with 13 (6.7%) infants aged <1 year and 181 (93.3%) older children aged ≥1 year. After the initial dose, only 1 (11.1%) infant, but 62 (57.9%) older children, achieved goal. Median number of anti-Xa levels until goal was 2 (interquartile range: 2-3) in infants and 1 (interquartile range: 1-2) in older children (P = .01). HA-VTE developed in 2 (15.4%) infants and 9 (5.0%) older children. Among children with anti-Xa level, HA-VTE developed less frequently in children who achieved (2.1%) than in those who did not achieve (13.6%) goal (P = .046). A total of 4 (2.1%) older children and no infants developed clinically relevant bleed. Among children with anti-Xa level, frequency of bleeding was comparable between children who did (3.2%) and did not achieve (0%) goal (P >.99).

CONCLUSIONS

Our findings suggest the effectiveness and safety of an anti-Xa level directed strategy of prophylactic enoxaparin. However, this strategy should be investigated in prospective controlled studies.

Incidence of Deep Vein Thrombosis in Cerebral Palsy Following an Orthopaedic Surgical Event

PURPOSE

The purpose of this study was to identify the incidence of venous thromboembolism (VTE) and characterize the demographics, comorbidities, and risk factors for patients with cerebral palsy (CP) having orthopaedic surgery.

METHODS

All patients diagnosed with CP who underwent an orthopaedic surgical procedure at one institution between 2008 and 2017 were identified. Diagnosis codes and associated patient events were recovered from the electronic medical record. Each VTE event was reviewed to ascertain an actual VTE episode related to a surgical event.

RESULTS

The review included 2583 orthopaedic surgical events in 1371 patients. Of the initial 88 cases identified, 28 cases had a deep thrombosis documented. Six cases of VTE occurred within 3 months following the surgical event. Three of these cases had thigh thrombosis, and 2 patients had upper arm thrombosis, and 1 patient had a superior vena cava thrombosis. On further workup, 5 of these 6 patients were identified as having a congenital hypercoagulable condition.

CONCLUSIONS

VTE is a relatively rare occurrence after orthopaedic surgery in pediatric patients with CP, but when it occurs, a full hematologic workup for a congenital hypercoagulable condition is indicated. Based on the low incidence of thigh thrombosis, routine pharmacological or intermittent mechanical calf compression is not recommended. A careful clinical and family history should be performed to identify patients with possible genetic hypercoagulable conditions who would merit prophylaxis.

LEVEL OF EVIDENCE

Level IV.

Impact of ABO Blood Group on the Development of Venous Thromboembolism in Children With Cancer: A Systematic Review and Meta-Analysis

BACKGROUND

Few studies have evaluated the impact of ABO blood group on the risk of venous thromboembolism (VTE) in pediatric populations. We performed a systematic review to determine whether children (0 to 18 y old) with non-O blood group have an increased risk of developing VTE compared with those with O blood group.

METHODS

We searched Ovid Medline, Embase, PubMed, Cochrane, Web of Science, and CINAHL online databases from inception to December 2018 to find studies involving blood grouping and VTE. Data was collected regarding patients' underlying diseases, sex, age, ABO blood group, and VTE frequency. A meta-analysis using the random effect model was performed, and heterogeneity was assessed with the I2 value.

RESULTS

Among 1280 unique articles identified, 7 studies (3 conference abstracts, 4 peer-reviewed journal articles) involving 609 VTE cases were included in the systematic review. Six studies were eligible for a meta-analysis; all involved patients with cancer. Blood group O was protective against VTE (odds ratio, 0.56; 95% confidence interval, 0.43-0.79). Findings were similar across sensitivity analyses.

CONCLUSIONS

This systematic review has documented that O blood group is protective against new-onset VTE in children with cancer. Larger studies across different ethnic backgrounds and disease categories are needed to confirm these findings.

Risk factors determining central venous access device-associated deep vein thrombosis resolution in children: a retrospective study

The risk factors associated with the probability of central venous access device (CVAD)-associated deep vein thrombosis (DVT) resolution have been hardly evaluated in children. Current guidelines suggest anticoagulation for a maximum of 3 months in patients with provoked DVT if the provoking factor is resolved. To know if the thrombus will resolve after anticoagulant therapy will help to choose whether to initiate and/or continue this treatment or not. We did a retrospective study of 85 pediatric patients (45 girls, 40 boys) with CVAD-associated DVT to examine the risk factors associated with lack of thrombus resolution in the first 6 months after diagnosis. Sixty-two children had their thrombosis resolved after a median of 50 days (p25-p75 25-97) since diagnosis. In multivariate analysis, variables significantly associated with no resolution were total occlusion (OR 12.50, 95% CI 2.99-52.14, p=.001), location in upper extremity, head, and neck veins (OR 17.70, 95% CI 1.64-191.43, p=.018); collateral circulation in the first 45 days after diagnosis (OR 33.55, 95% CI 2.42-464.71, p=.009); and having between 0 and 3 prothrombotic risk factors at diagnosis (OR 6.20, 95% CI 1.21-31.75, p=.029).Conclusion: CVAD-associated DVT resolution in children in the first 6 months since diagnosis was significantly lower if the thrombosis was occlusive, if it was located in the upper extremity, head, and neck veins; if collateral circulation was seen on ultrasound in the first 45 days; and/or when the patient showed less prothrombotic risk factors at diagnosis. What is Known: • The risk factors associated with central venous access device-associated deep vein thrombosis resolution have been hardly evaluated in children. • Current guidelines suggest anticoagulation for a maximum of 3 months in provoked vein thrombosis if the provoking factor is resolved. What is New: • Thrombus resolution was lower if it was occlusive, located in the upper extremity veins, if collateral circulation was seen, and with less prothrombotic risk factors at diagnosis. • To know if the thrombus will resolve after anticoagulation will help to choose whether to initiate and/or continue it or not.

A Real-time Risk-Prediction Model for Pediatric Venous Thromboembolic Events

BACKGROUND

Hospital-associated venous thromboembolism (HA-VTE) is an increasing cause of morbidity in pediatric populations, yet identification of high-risk patients remains challenging. General pediatric models have been derived from case-control studies, but few have been validated. We developed and validated a predictive model for pediatric HA-VTE using a large, retrospective cohort.

METHODS

The derivation cohort included 111 352 admissions to Monroe Carell Jr. Children's Hospital at Vanderbilt. Potential variables were identified a priori, and corresponding data were extracted. Logistic regression was used to estimate the association of potential risk factors with development of HA-VTE. Variable inclusion in the model was based on univariate analysis, availability in routine medical records, and clinician expertise. The model was validated by using a separate cohort with 44 138 admissions.

RESULTS

A total of 815 encounters were identified with HA-VTE in the derivation cohort. Variables strongly associated with HA-VTE include history of thrombosis (odds ratio [OR] 8.7; 95% confidence interval [CI] 6.6-11.3; P < .01), presence of a central line (OR 4.9; 95% CI 4.0-5.8; P < .01), and patients with cardiology conditions (OR 4.0; 95% CI 3.3-4.8; P < .01). Eleven variables were included, which yielded excellent discriminatory ability in both the derivation cohort (concordance statistic = 0.908) and the validation cohort (concordance statistic = 0.904).

CONCLUSIONS

We created and validated a risk-prediction model that identifies pediatric patients at risk for HA-VTE development. We anticipate early identification of high-risk patients will increase prophylactic interventions and decrease the incidence of pediatric HA-VTE.

Venous Thromboembolism After Pelvic Osteotomy in Adolescent Patients: A Database Study Characterizing Rates and Current Practices

BACKGROUND

Current risks and practices in medical prophylaxis of venous thromboembolism (VTE) after major elective lower extremity surgeries such as pelvic osteotomies have not been well-defined in the pediatric population. The purpose of this study was to (1) evaluate population rates of VTE in adolescents undergoing pelvic osteotomies, and (2) characterize current practices on types of VTE prophylaxis being utilized after pelvic osteotomies.

METHODS

The study evaluated the Pediatric Health Information System database between October 1, 2015 and January 1, 2020 for patients between 10 and 18 years of age meeting selected ICD-10 procedure and diagnosis codes relating to pelvic osteotomies. The rate of VTE was calculated within 90 days of index procedure. Types of pharmacologic prophylaxis were characterized. Continuous variables were compared with 2-sample t tests; proportions and categorical variables were compared with Fisher exact or χ2 tests, all with 2-tailed significance <0.05.

RESULTS

Of 1480 included patients, 9 were diagnosed with VTE within 90 days of surgery (VTE rate: 0.61%). Four of 9 (44.4%) had received pharmacologic prophylaxis postoperatively. There were no differences in baseline demographics or length of stay between patients that did or did not develop VTE (P>0.05). Overall, 52.0% received at least one form of pharmacologic prophylaxis postoperatively. The most common pharmacologic prophylaxis used was aspirin (47.6%), of which 64.4% received 81 mg dosing. There was no difference in VTE rates in those with or without prophylaxis (0.52% vs. 0.70%, P=0.75). However, those prescribed prophylaxis were significantly older (15.2±2.3 vs. 13.6±2.4 y, P<0.0001) and had a higher proportion of females (71.8% vs. 54.6%, P<0.01).

CONCLUSIONS

The overall rate of VTE in pediatric patients after pelvic osteotomies is non-negligible. There is heterogeneity in the type of anticoagulant utilized; however, VTE prophylaxis is most commonly prescribed in older adolescents and female patients. Guidelines for medical prevention of deep venous thrombosis and pulmonary embolism in the pediatric population are warranted after hip preservation surgery.

LEVEL OF EVIDENCE

Level IV, case series.

Venous Thromboembolism in Pediatric Inflammatory Bowel Disease: A Case-Control Study

OBJECTIVES

Inflammatory bowel disease (IBD) is associated with increased risk of venous thromboembolism (VTE). Despite this recognized risk, there are limited data and no anticoagulation guidelines for hospitalized pediatric IBD patients. The objectives of this study were to characterize pediatric IBD patients with VTE and determine risk factors.

METHODS

This was a nested case-control study comparing hospitalized children with IBD diagnosed with VTE to those without VTE over a decade at a large referral center. Standard descriptive statistics were used to describe the VTE group. Multivariable conditional logistic regression was used to assess risk factors.

RESULTS

Twenty-three cases were identified. Central venous catheter (CVC) presence (odds ratio [OR] 77.9; 95% confidence interval [CI]: 6.9--880.6; P < 0.001) and steroid use (OR 12.7; 95% CI: 1.3--126.4; P = 0.012) were independent risk factors. Median age at VTE was 17 years (interquartile range [IQR] 13.5--18.2), and in 48%, VTE was the indication for admission. Median duration of anticoagulation was 3.8 months (IQR 2.3--7.6), and there were no major bleeding events for patients on anticoagulation. There were no patients with known sequelae from VTE, though 22% had severe VTE that required interventions.

CONCLUSIONS

Pediatric patients with IBD are at risk for VTE, although the absolute risk remains relatively low. The safety and efficacy of pharmacologic thromboprophylaxis needs to be further evaluated in this population with attention to risk factors, such as steroid use and presence of CVC.

Central venous catheters are an important factor in paediatric thrombosis

AIM

To establish the incidence and characteristics of paediatric thrombosis (PT) in a Canadian tertiary care centre during the era of low molecular weight heparin (LMWH).

METHODS

A retrospective observational case study of all patients <18 years of age evaluated for arterial and venous thrombosis from May 2008 to July 2018 at McMaster Children's Hospital was conducted through the electronic medical record.

RESULTS

The incidence of PT was 52.2 per 10 000 hospital admissions (n = 477/91 462). Provoked thrombosis was more prevalent (88.9%, n = 424/477) than unprovoked (2.9%, n = 14/477) or idiopathic thrombosis (4%, n = 19/477). Half of PT were in children <2 years (51.2%, n = 244/477). Central vascular catheterisation was a contributory factor in more than half of thrombotic events (56.2%, n = 268/477), while trauma (1.1%, n = 5/477), oral contraceptives (4%, n = 19/477), infection (4%, n = 19/477), surgery (6.9%, n = 33/477) and malignancy (8.4%, n = 40/477) were also risk factors. Arterial ischaemic stroke was diagnosed in 11.1% of cases (n = 53/477), while pulmonary embolism was identified in 7.1% (n = 34/477) and 1.7% of cases were fatal (n = 8/477). LMWH was the first-line therapeutic of choice (47.8%, n = 228/477), with 28.1% (n = 134/477) requiring no intervention.

CONCLUSION

These data reiterate the elevated thrombosis risk to which infants and children with central vascular access are exposed.

Risk Assessment and Outcome of Venous Thromboembolism in Pediatric Population in an Academic Care Center of a Low-Middle Income Country

Venous thromboembolism (VTE) is a recognized complication of hospital stay in young patients in many developed countries, but such an information is largely unavailable from a low middle-income country (LMIC). This study aimed at identifying the frequency, risk factors, treatment options and outcome of deep venous thrombosis/pulmonary embolism (DVT/PE) in pediatric population in a tertiary care center from a LMIC. International classification of disease, ninth revision (ICD-9) was used to identify VTE in patients aged 0-18 years during January 2011 to September 2019. In-house computerized system was used to collect data for demographics, clinical and laboratory details. SPSS version 19 was used to analyzed data. The study was approved by Institutional ethical review committee (3872-Pat-ERC-15). During the study period, 134617 pediatric patients were hospitalized, DVT/PE was observed in 77 unique patients (47 males and 30 females) with a median (IQR) age of 14 (5-16) years equivalent to 5.9 VTE events /10,000 hospital admissions. Malignancy, community acquired infections and autoimmune diseases were the predominant risk factors (75%) in adolescent age-group while surgery for congenital heart anomalies was the primary reason (71%) in infants. Overall, lower extremity thrombosis was the most frequent (51%) followed by pulmonary embolism (25%). and upper extremity thrombosis (24%). Enoxaparin and unfractionated heparin were mainly used to treat VTE and all-cause mortality was 13% in the cohort studied. We observed substantial VTE events in pediatric patients during their hospital stay in a tertiary care center of a low-middle income country.

Inferior Vena Cava Filter in Childhood Septic Deep Vein Thrombosis

Inferior vena cava (IVC) filter in venous thromboembolism (VTE) is an alternative to anticoagulation when the latter is contraindicated. The use of IVC filter in pediatrics continues to be rare and has not increased despite the ever-increasing rates of childhood VTE. Historically, septic VTE was regarded as a contraindication to IVC filter. Safety and efficacy of IVC filters in septic VTE have been reported in adult patients but not in pediatric patients. In this study, we reported a safe use of IVC filter in a critically ill 12-year-old patient with a large IVC thrombus and multiple pulmonary embolisms with favorable outcome.

Pediatric stroke associated with a sedentary lifestyle during the SARS-CoV-2 (COVID-19) pandemic: a case report on a 17-year-old

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic-associated quarantine has led to a more sedentary lifestyle in teenagers. This may increase the risk for venous thromboembolism and a subsequent source of an ischemic stroke through a patent foramen ovale (PFO). Here, we report a pediatric stroke case likely due to these factors.

Coagulation disorders in Duchenne muscular dystrophy? Results of a registry-based online survey

Different complications of hemostasis have been reported in patients with Duchenne Muscular Dystrophy (DMD). These comprise an increased rate of bleeding-symptoms during scoliosis surgery but also thromboembolic complications such as pulmonary embolism, cerebral infarction, deep vein thrombosis or cardiac thrombus.

For this cross-sectional study, personalized online survey-links were forwarded to 682 registered patients with a genetically confirmed diagnosis of DMD via the German-Austrian DMD patient registry (www.dmd-register.de). The questionnaire enquired data regarding the degree of mobility, disposition to hematoma, epistaxis and gum bleeding, occurrence of peri- and postsurgical hemorrhage, stroke, deep vein thrombosis, and cardiac thromboembolism. Further data on regular medication and age were recorded.

Three-hundred-fifty-one DMD-patients completed the questionnaire (response rate of 51.5%). Of those, 164 (46.7%) were ambulatory and 187 (53.3%) were non-ambulatory. Age distribution was homogeneous. Two participants had a history of thromboembolic events (0.6%). Correlations analysis revealed no coherence with the degree of mobility, age or regular medication. A bleeding tendency was reported by 76 participants (21.7%). No significant correlations with age or degree of mobility were found. We found no association with underlying genetic variants.

Results of this patient registry-based survey do not indicate a distinct DMD-specific risk for thromboembolic events that exceeds the risk by typical comorbidities of chronic immobility and cardiac insufficiency in advanced stages of the disease. The results of this survey suggest a mild bleeding tendency in this DMD cohort, whereas a selection bias cannot be excluded.

Prophylaxis for Pediatric Venous Thromboembolism: Current Status and Changes Across Pediatric Orthopaedic Society of North America From 2011

INTRODUCTION

Pediatric venous thromboembolism (VTE) is a concern for orthopaedic surgeons. We sought to query the Pediatric Orthopaedic Society of North America (POSNA) members on current VTE prophylaxis practice and compare those results with those of a previous survey (2011).

METHODS

A 35-question survey was emailed to all active and candidate POSNA members. The survey consisted of questions on personal and practice demographics; knowledge and implementation of various VTE prophylaxis protocols, mechanical and chemical VTE prophylaxis agents, and risk factors; and utilization of scenarios VTE prophylaxis agents for various clinical scenarios. One- and two-way frequency tables were constructed comparing results from the current survey and those of the 2011 survey.

RESULTS

Two hundred thirty-nine surveys were completed (18% respondent rate), with most respondents from an academic/university practice reporting one or two partners (>60%). Half were in practice ≥15 years, and >90% reported an almost exclusive pediatric practice. One-third of the respondents reported familiarity with their institution-defined VTE prophylaxis protocol, and 20% were aware of an institutionally driven age at which all patients receive VTE prophylaxis. The most frequently recognized risk factors to guide VTE prophylaxis were oral contraceptive use, positive family history, and obesity. Respondents indicated a similar frequency of use of a VTE prophylaxis agent (either mechanical or chemical) for spinal fusion, hip reconstruction, and trauma (60% to 65%), with lower frequency for neuromuscular surgery (34%) (P < 0.001). One hundred thirty-seven respondents had a patient sustain a deep vein thrombosis, and 66 had a patient sustain a pulmonary embolism. Compared with responses from 2011, only 20 more respondents reported familiarity with their institution VTE prophylaxis protocol (75 versus 55). In 2018, aspirin was used more frequently than in 2011 (52% versus 19%; P < 0.0001) and enoxaparin was used less frequently (20% versus 41%; P < 0.0001).

DISCUSSION

Over the past 7 years since the first POSNA survey on VTE prophylaxis, most POSNA members are still unaware of their institution specific VTE prophylaxis protocol. Most respondents agree that either mechanical or chemical VTE prophylaxis should be used for spinal fusion, hip reconstruction, and trauma. The use of aspirin as an agent of chemical VTE prophylaxis has increased since 2011.

LEVEL OF EVIDENCE

Level IV. Type of evidence: therapeutic.

Development of a perioperative venous thromboembolism prophylaxis algorithm for pediatric orthopedic surgical patients

Venous thromboembolism (VTE) has been recognized as a rare but potentially serious complication in pediatric orthopedic patients. However, standardized guidelines for screening and management of at-risk patients do not exist. The aim of the study was to develop a VTE prophylaxis screening tool for postoperative orthopedic patients after conducting an institutional needs assessment survey. A needs assessment survey was conducted after institutional ethics board approval. Development of perioperative VTE prophylaxis algorithm for pediatric orthopedic surgical patients was planned after thorough literature review, consultation with national and international experts as well as using a modified nominal and consensus development conference (serial meetings) method for reaching a consensus. NAS as well as discussion with stakeholders indicated support for development of perioperative VTE prophylaxis algorithm for orthopedic patients. Using above methods, a VTE prophylaxis algorithm was developed and implemented at IWK Health Center. The present study involved development of a perioperative VTE prophylaxis algorithm for pediatric orthopedic surgical patients that could be easily and rapidly administered as a point of care assessment tool.

Comparative validation study of risk assessment models for pediatric hospital-acquired venous thromboembolism

BACKGROUND

Risk assessment models (RAMs) have been developed to identify children at high risk of hospital-acquired venous thromboembolism (HA-VTE). None have been externally validated nor compared.

OBJECTIVES

The objective was to compare performance of these RAMs by externally validating them using the Children's Hospital-Acquired Thrombosis (CHAT) Registry, ie, a multicenter database of children with radiographic-confirmed HA-VTE and corresponding controls.

PATIENTS/METHODS

Risk assessment models were included if the full logistic regression equation was available and all RAM variables were collected in the CHAT Registry. A random sample of 200 cases and 200 controls was selected. The performance of the RAMs was assessed for discrimination using area under the receiver operating characteristic curves (AUROC), and calibration using plots, slopes, and intercepts, and the Hosmer-Lemeshow test.

RESULTS

Three RAMs were included. Each had excellent discrimination with AUROC ≥ 0.85. However, calibration was generally poor, with calibration slopes significantly different from 1 (0.71, P < .001; 1.44, P = .002; 0.68, P < .001), intercepts significantly different from 0 (-1.64, P < .001; -0.62, P < .001; 0.78, P < .001), and Hosmer-Lemeshow test P < .001 for each. Exceptions included the Arlikar et al and Atchison et al RAMs for pediatric HA-VTE in non-intensive care unit (ICU) patients and ICU patients, respectively, despite derivation from ICU and non-ICU patients, respectively. In these subpopulations, both showed excellent discrimination and good calibration.

CONCLUSION

Given the lack of adequate calibration for evaluated RAMs, further investigation and refinement of RAMs for pediatric HA-VTE is needed prior to application of a RAM in a clinical setting or risk-stratified clinical trial of primary thromboprophylaxis against HA-VTE in children.

Venous Thromboembolism in Children and Young Adults in Korea: Analysis of the Korean Health Insurance Review and Assessment Service Database

BACKGROUND

Venous thromboembolism (VTE) is very rare in childhood. Nevertheless, its incidence has increased recently. This study aimed to identify risk factors for developing thrombosis in childhood cancers and other childhood diseases through the Korean Health Insurance Review and Assessment Service database.

METHODS

Data were extracted from the Korean Health Insurance Review and Assessment Service database. Children and young adults from 1 month to 29 years of age were eligible, and 21,747 cases of VTE between January 2008 and December 2016 were identified.

RESULTS

The VTE incidence was high in children younger than 1 year of age. After 1 year of age, its incidence decreased rapidly and gradually increased. The VTE incidence for children between 0 and 1 year of age was 10.23-fold higher than that for those between 1 and 5 years of age. Annual VTE incidence increased by year. The age-standardized annual incidence rates were 9.98 per 100,000 population in 2008 and 22.53 per 100,000 population in 2016. The age-standardized annual incidence rate increased 2.25-fold during the 8 years. The lower extremity was the most common site of venous thrombosis.

CONCLUSION

The incidence of VTE in a population younger than 30 years was 13.11 per 100,000 persons in Korea. We found a bimodal age distribution of the VTE incidence with peaks at infancy and again after 16 years. The incidence of portal vein thrombosis was high in infants, and infection and malignancy were the most common comorbidities in patients with VTE.

Promising biomarkers for the prediction of catheter-related venous thromboembolism in hospitalized children: An exploratory study

BACKGROUND

Pediatric venous thromboembolism (VTE) has increased over the past 10 years, with central venous catheters (CVC) being the strongest risk factor. Current tools are not sufficient to predict VTE risk. The utility of biomarkers in predicting CVC-related VTE has been minimally explored. Our objective is to determine the utility of microparticles (MPs), factor VIII (FVIII) activity, and thrombin generation (TG) in prospectively predicting VTE occurrence in hospitalized children with CVCs.

PROCEDURE

In this nested case-control pilot study, consecutive hospitalized children needing CVC placement (1 month to 21 years) were enrolled. Venous samples were collected prior to or within 24 h of CVC placement. MPs were measured using factor Xa initiated clot-based assay. FVIII was measured using a one-stage clot-based assay. TG was measured using calibrated automated thrombogram.

RESULTS

There were three CVC-related VTE events (7%) in our cohort of 42 subjects. Xa clotting time (XaCT) ratio was lower (0.68 ± 0.07 vs 0.95 ± 0.21, P = .4), while FVIII (461 ± 120 vs 267 ± 130, P = .02), peak thrombin (418 ± 89 vs 211 ± 101, P = .001), endogenous thrombin potential (ETP) (1828 ± 485 vs 1282 ± 394, P = .03), and velocity index (VI) (182 ± 28 vs 75 ± 53, P = .001) were higher in subjects with CVC-related VTE compared to those without CVC-related VTE. Sensitivity/specificity analysis revealed optimal cutoff values for XaCT ratio (0.75), FVIII (370), ETP (1680), peak (315), and VI (130), with receiver operating characteristic area under the curve values >0.9.

CONCLUSION

MPs, FVIII, and TG can potentially predict pediatric CVC-related VTE in a prospective fashion. Stratification according to VTE risk may aid in guiding preventative efforts in future studies.

Central Venous Line Associated Deep Vein Thrombosis in Hospitalized Children

An increase in the incidence of deep vein thrombosis (DVT) has been reported in pediatric patients over the past decade. The presence of central venous line (CVL) is a major contributing risk factor with conflicting data on the relative risk of DVT with various types of central lines. We aimed to assess the incidence of and identify potential risk factors for DVT overall and with different types of CVL individually. A retrospective chart review of pediatric patients with a CVL placed at Cleveland Clinic Children's from 2011 to 2016 was conducted. Data collected included demographics, potential risk factors, CVL characteristics and related thrombotic events. The study cohort consisted of 376 CVLs in 325 patients between 0 and 26 years of age. There were 1.6 thrombi per 10,000 line-days (95% confidence interval: 1.0, 2.5), and the overall incidence of DVT was 5.1%. The incidence of DVT was highest with tunneled catheters (5/16=31%) versus with peripherally inserted central catheters (4/111=3.6%) or with ports (10/249=4%, P<0.001), and whereas there were overarching significant risk factors for CVL-associated thrombi, these risk factors differed in significance when analyzed by the CVL type. The study supports the need for continued improvement in pediatric hospital practices for early identification of patients at a higher thrombosis risk.

Central venous lines in critically ill children: Thrombosis but not infection is site dependent

BACKGROUND

Central venous catheters (CVC) are vital to the management of critically ill children. Despite efforts to minimize complications, central line associated bloodstream infection (CLABSI) and venous thromboembolisms (VTE) still occur.

METHODS

We performed a retrospective review of a prospectively collected database for children admitted to the pediatric intensive care unit (PICU) between November 2013 and December 2016.

RESULTS

In total, 2714 CVC were in place, 979 of which were percutaneous CVC. During the study period, 21 CLABSI (1.6/1000 line days) were identified, of which, nearly half (n = 9, 42.9%) were associated with percutaneous CVC (2.6/1000 line days). Poisson regression analysis did not identify a single risk factor for CLABSI when adjusting for line type, anatomic location and laterality of placement, geographic location of placement, length of PICU admission, presence of gastrostomy tube, concurrent mechanical ventilation, age, weight, and height. Forty clinically significant VTE (2.9/1000 line days) were identified, with percutaneous CVC having the highest incidence (7.5/1000 line days, p < 0.001). Of percutaneous CVC, clinically significant VTE were more often associated with femoral vein cannulation (14.8/1000 line days) compared to internal jugular and subclavian vein (2.5 and 2.4/1000 line days, respectively, p < 0.001).

CONCLUSION

This data suggests that the femoral site may be an important risk factor that should be considered in prevention strategies for catheter-associated VTE in children.

LEVEL OF EVIDENCE

III.

Prophylactic Use of Enoxaparin in Adolescents During Bariatric Surgery-a Prospective Clinical Study

INTRODUCTION

Severe obesity predisposes youth to a higher risk of venous thromboembolism (VTE). This study evaluates a BMI-stratified prophylactic dosing regimen of enoxaparin in adolescents with severe obesity undergoing surgery.

METHODS

Adolescents aged 12-20 years received prophylactic enoxaparin at 40 mg SC (for a BMI < 50 kg/m²) and 60 mg SC (for a BMI ≥ 50 kg/m²) every 12 h until discharge. Blood samples were drawn at pre-dose, 1, 2, 4, 6, and 12 h. Plasma Anti-Factor Xa (Anti-FXa) activity was used as a surrogate marker for enoxaparin pharmacokinetics.

RESULTS

Ten female and two male obese adolescents (age range 14-19 years) had a mean BMI of 49.9 kg/m² (38.4-58 kg/m²). Four patients had a BMI of less than 50 kg/m² and received 40 mg enoxaparin, resulting in a mean dosage of 0.352 ± 0.070 mg/kg body weight. Eight patients were dosed with 60 mg enoxaparin every 12 h, resulting in a mean dosage of 0.395 ± 0.028 mg/kg. Peak plasma anti-FXa activity (C_max) ranged from 0.14 to 0.30 IU/mL, median C_max was 0.205 IU/mL. Median T_max was 5.67 h (range 3.78-7.52 h). Median AUC_i was 1.00 h IU/mL (range 0.42-1.67 h IU/mL). Ten out of 12 patients (83%) reached the primary endpoint with anti-FXa activity in the range for VTE prevention (0.1-0.3 IU/mL).

CONCLUSIONS

Our dosing scheme of 40 mg vs. 60 mg enoxaparin stratified according to BMI proved to be effective in reaching prophylactic anti-FXa activity in 83% of adolescent patients.

A Critical Evaluation of Enoxaparin Dose Adjustment Guidelines in Children

OBJECTIVES

The purposes of this study are to perform a large-scale evaluation of the standardized dosage adjustment nomogram recommended by the American College of Chest Physicians (CHEST) for the management of enoxaparin in hospitalized pediatric patients and to determine the necessity of routine and repeated anti-factor Xa (anti-Xa) levels.

METHODS

A retrospective cohort study was designed, and charts were reviewed in a single tertiary care institution for all patients who received enoxaparin between October 1, 2010, through September 30, 2016. Patients were included if they were receiving treatment doses of enoxaparin according to the pediatric CHEST guidelines, had a subtherapeutic or supratherapeutic anti-Xa level drawn at 3.5 to 6 hours after a dose, had a dose changed in an attempt to attain a therapeutic anti-Xa level, and had a second anti-Xa level drawn 3.5 to 6 hours after the dose change. Descriptive statistical methods were used to characterize the ability of dose adjustment via a nomogram to attain an anti-Xa of 0.5 to 1 unit/mL.

RESULTS

A total of 467 patients were identified who received the appropriate initial dose and dosage adjustment and whose levels were drawn according to the CHEST guidelines. In patients who had an initial anti-Xa level of <0.35 units/mL and received the nomogram recommended dose increase of 25% ± 5%, 28 out of 96 patients (29.2%) reached therapeutic levels. Of 197 patients who had an initial anti-Xa level between 0.35 and 0.49 units/mL and who received the nomogram recommended dose increase of 10% ± 5%, 116 (58.9%) reached therapeutic levels. Of 50 patients with an initial anti-Xa level between 1.1 and 1.5 units/mL and who received the nomogram dose decrease of 20% ± 5%, 31 (62%) reached therapeutic levels.

CONCLUSIONS

The current dosage adjustment nomogram recommended by the CHEST guidelines does not reliably lead to therapeutic anti-Xa levels when used to adjust enoxaparin doses in pediatric patients.

Venous Thromboembolism in Female Adolescents: Patient Characteristics

STUDY OBJECTIVE

Our goal was to describe the period prevalence of venous thromboembolism (VTE) and characterize adolescent female patients diagnosed with VTE by describing their age, race, and number of comorbidities. Female adolescents with estrogen exposure were of particular interest because estrogen-containing contraceptives increase the risk of VTE.

DESIGN, SETTING, PARTICIPANTS, AND INTERVENTIONS

We queried the Pediatric Health Information System database for International Classification of Diseases, Ninth/Tenth Revision, Clinical Modification codes to identify female patients aged 12-18 years diagnosed with a VTE or pulmonary embolism from April 2006 to March 2016 in the United States. Patient demographic characteristics and comorbidities were also analyzed. We divided our study population into two five-year groups and calculated the change in period prevalence of VTE between those groups.

MAIN OUTCOME MEASURES

Primary diagnosis of VTE in the extremities, or pulmonary embolism.

RESULTS

The period prevalence of VTE increased from 2.3 female adolescents per 10,000 hospitalized children (group 1) to 3.3 per 10,000 (group 2), representing a statistically significant increase of 0.010% (P < .001). Caucasian and black individuals were most commonly affected. The number of girls affected increased steadily from ages 12 to 16 years and a large percentage (59.6%) had four or more comorbidities. In patients (n = 32) with estrogen exposure, more than 96% had one or more comorbidity in addition to estrogen exposure.

CONCLUSION

Pediatric health care providers should be aware that the period prevalence of VTEs in female adolescents is increasing. Those with a history of estrogen exposure rarely develop VTEs from estrogen alone and they typically have multiple comorbidities.

Incidence and risk factors associated with 30-day post-operative venous thromboembolism: A NSQIP-pediatric analysis

INTRO

Venous thromboembolism (VTE) is a rare event in children, but can cause significant morbidity and mortality. The majority of research on pediatric VTE has been in the trauma and critical care populations. The incidence of VTE after surgery in children is not well-established.

OBJECTIVE

The objective was to evaluate the incidence of VTE in the 30 days after surgery, as well as associated risk factors.

STUDY DESIGN

All cases in the National Surgical Quality Improvement Program Pediatric (NSQIPP) database from 2012 to 2015 were assessed for presence of post-operative VTE. Demographic, clinical, and peri-operative characteristics were collected. Descriptive statistics were performed, and multiple logistic regression models were created to estimate associated risk of VTE.

RESULTS

In a cohort of 267,299 surgical cases, the 30-day incidence of post-operative VTE was 12 per 10,000 cases (0.12%). VTE incidence followed a bi-modal distribution, highest in infants and adolescents (Figure). Malignancy, pre-operative illness, and greater anesthetic times were associated with increased risk of VTE.

DISCUSSION

The incidence of post-operative VTE in NSQIPP is similar to that seen in pediatric trauma and critical care populations. Risk factors are also consistent, including baseline illness, immobility, and prolonged anesthetic time.

CONCLUSION

Post-operative VTE in children occurs infrequently, yet certain individuals are at increased risk and thus guidelines for prophylaxis and treatment are needed.

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.

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.