Are low-molecular-weight heparins safe and effective in children? A systematic review

Incidence of acute Deep Vein Thrombosis in pediatric and adolescent orthopedic trauma hospitalized patients and effect of rivaroxaban treatment

OBJECTIVE

Deep vein thrombosis (DVT) provoked by orthopedic trauma is increasing in pediatric hospitalized patients. The purpose of our study is to identify the prevalence of acute DVT in pediatric and adolescent orthopedic trauma hospitalized patients and focus on evaluating the anticoagulation strategies and the clinical outcomes after a confirmed acute DVT.

METHODS

Patients (age ≤18 years) with a confirmed acute DVT admitted for orthopedic trauma between September 2017 and December 2023 were included. Patients were classified into the non-anticoagulation (NA), the in-hospital anticoagulation (IHA), and the in-and-out-of-hospital anticoagulation (IOHA) groups based on their anticoagulation regimen. Efficacy outcomes were the venous thromboembolism (VTE) recurrence within 3 months and change in thrombus burden by repeat imaging at 2 weeks after discharge compared with baseline. Safety outcomes were major bleeding (MB) and clinically relevant non-major bleeding (CRNMB) within 3 months.

RESULTS

Of the 11,206 pediatric and adolescent orthopedic trauma inpatients, 94(median age,16 [15, 18] years) were diagnosed with acute DVT, with an incidence of 0.84 %, of which 8(8.5 %) received NA, 41(43.6 %) received IHA, and 45(47.9 %) received IOHA. After the diagnosis of DVT, of patients who received anticoagulation, 97.9 % were treated with rivaroxaban as an oral anticoagulant, and 71.7 % received an LMWH course of ≥5 days before starting rivaroxaban therapy. With a median anticoagulation course of 22(8, 37.3) days, the duration in the IOHA was significantly longer than the IHA (37 days vs. 8 days, p = 0.000). No patients experienced recurrent VTE and MB at 3 months, and 1 received IOHA had a CRNMB event (0 % vs. 0 % vs. 2.2 %, p = 1.000). Thrombus resolution was significantly higher in patients who received anticoagulation therapy (IOHA 91.1 % vs. IHA 80.5 % vs. NA 37.5 %, P = 0.002), and thrombus-no relevant change was significantly lower in patients who received the IOHA strategy compared with the other groups (4.4 % vs. 19.5 % vs. 62.5 %, P = 0.000).

CONCLUSIONS

A rivaroxaban-predominant IOHA strategy significantly reduced the thrombotic burden without increasing the risk of bleeding for the treatment of DVT in adolescents with orthopedic trauma. Duration of anticoagulation therapy <6 weeks appears appropriate for adolescent orthopedic trauma-related DVT.

Anticoagulation of pediatric patients with venous thromboembolism in 2023

Venous thromboembolism (VTE) is a rare and heterozygous disease in children. Management of VTE in children is complicated by age-related differences in epidemiology, recurrent VTE and bleeding risk, hemostatic proteins and pharmacokinetics of anticoagulants. Recently, the choice of anticoagulation has expanded to oral factor IIa and Xa inhibitors, which have been authorized for children for treatment of acute VTE and extended secondary prevention. These drugs have several properties that make them extremely suitable for use in children, including oral administration, antithrombin independence, less interactions with food and drugs and no need for monitoring. Unfortunately, the phase 3 studies had many exclusion criteria, and only a few term neonates and infants were included in these studies. Additional real-world data is needed to make evidence-based recommendations in these age and patient groups, as well.

Is the current therapeutic dosage of nadroparin adequate for neonates and infants under 8 months with thromboembolic disease? a population pharmacokinetic study from a national children's medical center

Objectives: Nadroparin, a low-molecular-weight-heparin is commonly used off-label in neonates and infants for thromboembolic events prevention. However, the recommended dosing regimen often fails to achieve therapeutic target ranges. This study aimed to develop a population pharmacokinetic (PK) model of nadroparin to determine an appropriate dosing regimen for neonates and infants less than 8 months. Methods: A retrospective chart review was conducted on patients treated with nadroparin at Children's Hospital of Fudan University between July 2021 and December 2023. A population PK model was developed using anti-Xa levels, and its predictive performance was evaluated internally. Monte Carlo simulations were performed to design an initial dosing schedule targeting anti-Xa levels between 0.5 and 1 IU/mL. Results: A total of 40 neonates and infants aged less than 8 months with gestational age ranging from 25 to 41 weeks treated with nadroparin were enrolled in the study for analysis. A one-compartment PK model with first order absorption and elimination was adequately fitted to the data. Creatinine clearance was identified as a significant factor contributing to inter-individual variability in clearance. The typical population parameter estimates of clearance, distribution volume and absorption rate in this population were 0.211 L/h, 1.55 L and 0.495 h-1, respectively. Our findings suggest that current therapeutic doses of nadroparin (150-200 IU/kg q12 h) may result in subtherapeutic exposure, thus higher doses might be required. Conclusion: The present study offers the first estimation of PK parameters for nadroparin in preterm or term neonates and infants less than 8 months utilizing the model. Our findings have potential implications for recommending initial personalized dosages, particularly among patient populations exhibiting similar characteristics.

Efficacy and Safety of Direct Oral Anticoagulants in Pediatric Venous Thromboembolism: A Systematic Review and Meta-Analysis

OBJECTIVES

To assess the efficacy and safety of direct oral anticoagulants (DOACs) in comparison to standard-of-care (SOC) anticoagulants in the management and prophylaxis of thromboembolic events in pediatric populations.

METHODS

A comprehensive search of electronic databases was conducted to identify relevant studies published between January 1, 2015, and December 18, 2022. A meta-analysis was undertaken to evaluate the effect of DOACs on clinically significant endpoints, employing trial-level data with harmonized endpoint definitions. The primary outcome was venous thromboembolism (VTE). Odds ratios (ORs) with 95% confidence intervals (CIs) were calculated. The study was registered with INPLASY (2022120065).

RESULTS

Three studies encompassing 934 subjects were included. The incidence of VTE was reduced in patients administered DOACs compared to those on SOC anticoagulants (OR 0.41 [95% CI 0.19-0.93], I² = 0%, P = 0.03). No significant differences were observed between the DOAC and SOC groups in all-cause mortality (OR 0.50 [95% CI 0.07-3.59], I² = 0%, P = 0.35) or serious adverse events (OR 0.75 [95% CI 0.50-1.12], I² = 0%, P = 0.16). The risk of major bleeding (OR 0.50 [95% CI 0.13-1.87], I² = 44%, P = 0.30) and clinically relevant non-major bleeding (OR 1.23 [95% CI 0.50-3.00], I² = 0%, P = 0.65) exhibited no significant differences between the groups.

CONCLUSIONS

DOACs are associated with a reduced risk of VTE in pediatric patients without increasing the risk of bleeding, all-cause mortality, or serious adverse events when compared to SOC anticoagulants. DOACs may be an alternative for the treatment and prevention of thromboembolic events in the pediatrics.

A high rate of post thrombotic complication in pediatric portal vein thrombosis

INTRODUCTION

Portal vein thrombosis (PVT) is a rare disease in children and may be complicated by portal hypertension (PH), hepatopulmonary syndrome (HPS) and portopulmonary hypertension (PPHTN) but their incidence and risk factors are unknown.

METHODS

An observational, retrospective cohort study of all consecutive children (≤18 years) with PVT treated at the Emma Children's Hospital Amsterdam University Medical Centers between January 1996 and January 2022 was conducted to identify the incidence and risk factors of these post thrombotic complications (PTC) in pediatric patients.

RESULTS

In total 43/ 703 thrombosis patients had PVT (boys 72.1 %; mean age 1.3 ± 0.5 years). Overall, 51 % of patients developed PH (n = 22), complicated by PPHTN in one of them. In 16 of 22 patients, PVT presented with portal hypertension. Clinically relevant bleeding due to portal hypertension occurred in 13 (59.1 %) patients with PH. The mean age at the first clinically relevant bleeding was 5.1 ± 5.9 years. Risk factors for the development of PH were lack of complete thrombus resolution (OR 24.3, 95 % CI 1.2-7.0; p = 0.008) and unprovoked VTE (OR, 35.4; 95 % CI 1.4-6.3; p = 0.012). Median time from PVT to PH was 137 days (range: 0 days to 5.04 years).

CONCLUSION

We demonstrated that half of the patients develop PH after PVT, with a lack of thrombus resolution and unprovoked VTE as independent risk factors. This high incidence underlines the importance of long-term standardized follow-up of patients after PVT and standard screening in patients at risk of PTC.

Massive pulmonary embolism in Klippel-Trenaunay syndrome after leg raising: A case report

BACKGROUND

Klippel-Trenaunay syndrome (KTS) is a rare congenital disorder characterized by a combination of capillary malformations, soft-tissue or bone hypertrophy, and varicose veins or venous malformations. The syndrome predisposes patients to hypercoagulable states, including venous thromboembolism and pulmonary embolism (PE).

CASE SUMMARY

A 12-year-old girl with KTS was scheduled excision of verrucous hyperkeratosis in the left foot and posterior aspect of the left leg and left thigh and excision of a cutaneous hemangioma in the right buttock. After induction, the surgeon elevated the patient’s leg for sterilization, whereupon she experienced a massive PE and refractory cardiac arrest. Extracorporeal membrane oxygenation (ECMO) was performed after prolonged resuscitation, and she had a return of spontaneous circulation. After this episode, the patient was discharged without any neurologic complications.

CONCLUSION

The mechanism of PE, a lethal disease, involves a preexisting deep vein thrombosis that is mechanically dislodged by compression or changing positions and travels to the pulmonary artery. Therefore, patients predisposed to PE should be prescribed prophylactic anticoagulants. If the patient has unstable vital signs, resuscitation should be started immediately, and extracorporeal cardiopulmonary resuscitation should be considered in settings with existing ECMO protocols, expertise, and equipment. Awareness of PE in patients with KTS while leg raising for sterilization is critical.

50 Years of Pediatric Hemostasis: Knowledge, Diagnosis, and Treatment

Studies from the past 50 years have contributed to the expanding knowledge regarding developmental hemostasis. This is a dynamic process that begins in the fetal phase and is characterized by physiological variations in platelet counts and function, and concentrations of most coagulation factors and the native coagulation inhibitors in early life, as compared with adulthood. The developmental hemostasis studies since the 1980 to 1990s established the laboratory reference values for coagulation factors. It was only a decade or two later, that thromboelastography (TEG) or (rotational thromboelastometry [ROTEM]) as well as thrombin generation studies, provided special pediatric reference values along with the ability to evaluate clot formation and lysis. In addition, global whole blood-based clotting assays provided point of care guidance for proper transfusion support to children hospitalized in intensive care units or undergoing surgery. Although uncommon, thrombosis in children and neonates is gaining increasing recognition, typically as a secondary complication in sick children. Bleeding in children, and particularly intracerebral hemorrhage in newborns, still represent a therapeutic challenge. Notably, our review will outline the advancements in understanding developmental hemostasis and its manifestations, with respect to the pathophysiology of thrombosis and bleeding complications in young children. The changes of transfusion policy and approach to thrombophilia testing during the last decade will be mentioned. Subsequently, a brief summary of the data on anticoagulant treatments in pediatric patients will be presented. Finally, we will point out the 10 most cited articles in the field of pediatric and neonatal hemostasis.

Direct oral anticoagulants versus standard anticoagulation in children treated for acute venous thromboembolism

Direct oral anticoagulants (DOACs) are widely used to treat venous thromboembolism (VTE) in adults. Little attention is given to pediatric VTE (PVTE). The objective of this study is to study the efficacy and safety of DOACs in published PVTE randomized control trials (RCTs). PubMed, Embase, China National Knowledge Infrastructure, the Cochrane Library, SinoMed, and ClinicalTrials.gov were searched until 2021, to identify RCTs that enrolled patients with VTE <18 years of age who received DOACs versus standard anticoagulation. Outcomes were evaluated using the Mantel-Haenszel method of random-effects model. Our study evaluated seven RCTs that included 1139 cases of PVTE, which had a low risk of publication and assessment bias. Compared with standard anticoagulation, patients receiving DOACs presented a lower rate of recurrent VTE (relative risk [RR], 0.42 [confidence interval {CI}, 0.20 to 0.89]), similar mortality rate (RR, 0.50 [CI, 0.07 to 3.57]), major bleeding (RR, 0.46 [CI, 0.14 to 1.57]), and higher clinically relevant nonmajor bleeding (RR, 2.71 [CI, 1.05 to 7.02]) with low heterogeneity. Limiting to subgroups, dabigatran and rivaroxaban yielded similar findings, except for a higher incidence of nonmajor bleeding during rivaroxaban use. DOACs could be an alternative to standard anticoagulation in PVTE. Dabigatran and rivaroxaban have similar effects. IMPACT: In venous thromboembolism (VTE), direct oral anticoagulants (DOACs) are widely used as a substitution for standard anticoagulation in most situations for adults; however, little attention is paid to the pediatric population. For pediatric VTE, previous meta-analyses have emphasized the epidemiology, risk factors, and the use of traditional anticoagulants, and seldom reported the use of novel oral anticoagulants. This is the first meta-analysis of randomized controlled trials that focuses on the efficacy outcomes and safety endpoints of DOACs compared with standard anticoagulation in pediatric VTE.

Thromboprophylaxis for children hospitalized with COVID-19 and MIS-C

Background

Limited data exist about effective regimens for pharmacological thromboprophylaxis in children with acute coronavirus disease 2019 (COVID-19) and multisystem inflammatory syndrome in children (MIS-C).

Objectives

Study the outcomes of institutional thromboprophylaxis protocol for primary venous thromboembolism (VTE) prevention in children hospitalized with acute COVID-19/MIS-C.

Methods

This single-center retrospective cohort study included consecutive children (aged less than 21 years) with COVID-19/MIS-C who received tailored intensity thromboprophylaxis, primarily with low-molecular-weight heparin, from April 2020 through October 2021. Thromboprophylaxis was given to those with moderate to severe disease based on the World Health Organization scale and exposure to two or more VTE risk factors. Therapeutic intensity was considered for severe illness. Clinical recovery along with D-dimer improvement determined thromboprophylaxis duration. Outcomes were incident VTEs, bleeding, and mortality.

Results

Among 211 hospitalizations, 45 (21.3%) received thromboprophylaxis (COVID-19, 16; MIS-C, 29). Median age was 14.8 years (interquartile range [IQR], 8.9-16.1). Among 35 (77.8%) with severe illness, 27 (60.0%) required respiratory support, and 19 (42.2%) required an intensive care unit stay. Median hospitalization was 6 days (IQR, 5.0-10.5). Median thromboprophylaxis duration was 19 days (IQR, 6.0-31.0) with therapeutic intensity in 24 (53.3%) and prophylactic in 21 (46.7%). Outcomes were as follows: VTE, 1 (2.2%); death, 1 (2.2%, unrelated to bleeding/thrombosis); major/clinically relevant nonmajor bleeding, 0; and minor bleeding, 7 (15.5%). D-dimer was elevated in a majority at diagnosis (median, 2.3; IQR, 1.2-3.3 mg/ml fibrinogen-equivalent units) and was noninformative in assessing disease severity. D-dimer normalized at thromboprophylaxis discontinuation.

Conclusions

Our experience of using clinically directed thromboprophylaxis with tailored intensity approach for children hospitalized with COVID-19 and MIS-C favors its inclusion in current standard of care. The role of D-dimer in directing thromboprophylaxis management deserves further evaluation.

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.

Clinical and genetic features of Chinese pediatric patients with severe congenital protein C deficiency who first presented with purpura fulminans: A case series study and literature review

INTRODUCTION

Purpura fulminans (PF) is a hematological emergency that can be caused by severe congenital protein C (PC) deficiency. It has been rarely reported in the Chinese population. We aimed to characterize the clinical and genetic features of Chinese pediatric patients with severe congenital PC deficiency who first presented with PF.

MATERIALS AND METHODS

Twelve pediatric patients were diagnosed with severe congenital PC deficiency with PF, which was diagnosed based on our hospital records and previous reports from 1988 to July 2021 in China. We evaluated the clinical and genetic features of these patients.

RESULTS

Nine patients (9/12, 75%) had onsets that were observed within the first 48 h after birth. Six patients had a family history of thromboembolism. There was no consanguinity. Other symptoms were intracranial thrombosis or hemorrhage (4, 33.3%), ocular lesions (2, 16.7%), gastrointestinal hemorrhage (2, 16.7%) and kidney infarction before birth (1, 8.3%). All but one of the patients (one case not detected) had a plasma PC activity of <10%. The genetic study indicated that in the eight patients with inherited PC deficiency, two were homozygous, five were compound heterozygous and one was heterozygous for PC deficiency.

CONCLUSION

This is the first and largest case series of Chinese pediatric patients with severe congenital PC deficiency who first presented with PF. It has been shown that treatment with both fresh frozen plasma and anticoagulants is recommended when PC concentrate is not easily available, especially in developing countries.

Venous Thromboembolic Complications in Pediatric Gastrointestinal Diseases: Inflammatory Bowel Disease and Intestinal Failure

In children with gastrointestinal disorders such as inflammatory bowel disease (IBD) and intestinal failure (IF), the risk of venous thromboembolism (VTE) is increased. VTE may lead to pulmonary embolism, sepsis and central line infection, stroke and post-thrombotic syndrome. The purpose of this review is to summarize current knowledge and recent advances around VTE management in pediatric gastroenterology with a focus on IBD and IF. The VTE incidence in children with IBD is reported to be around 4-30 per 10,000 patient-years, with higher incidences for hospitalized children. While in general, IF is less common than IBD, the VTE incidence in children with IF is around 750 per 10,000 patient-years. The most common risk factors for development of VTE involve deviations leading to Virchow's triad (endothelial damage, stasis, and hypercoagulability) and include active inflammation, particularly with colonic involvement, presence of a central venous catheter, underlying thrombophilia, reduced mobility, surgery, and hospitalization. Classes of anticoagulants used for treatment of VTE are low molecular weight heparins and vitamin K antagonists. However, the use of direct oral anticoagulants for treatment or prevention of VTE has not been studied in this pediatric population yet. Pediatric gastroenterologists apply different VTE prevention and treatment strategies due to lack of literature and lack of consensus. We discuss the role of primary and secondary prophylactic use of anticoagulants, and provide tools and recommendations for screening, prevention and management for the specific pediatric populations.

Validation of risk assessment models for venous thromboembolism and bleeding in critically ill adolescents

OBJECTIVE

To determine the performance of risk assessment models that were developed for adults, in predicting venous thromboembolism (VTE) and bleeding in critically ill adolescents.

STUDY DESIGN

We conducted a retrospective cohort study of adolescents 12 to 17 years old admitted to the pediatric intensive care unit who received cardiopulmonary support but did not have VTE on admission nor received anticoagulation. Discrimination, using areas under the receiver operating characteristic (AUROC) and precision-recall (AUPRC) curves, and calibration, using Hosmer-Lemeshow test, of the Geneva, Padua, IMPROVE VTE and IMPROVE Bleed models were calculated.

RESULTS

Of 536 adolescents analyzed, 7 (1.3%) developed VTE and 13 (2.4%) bled. AUROCs of the Geneva, Padua and IMPROVE VTE models ranged from 0.46 to 0.59, with 95% confidence intervals (CI) including 0.5. AUPRCs ranged from 0.011 to 0.017, with 95% CIs including 0.013. Only IMPROVE VTE model had non-statistically significant Hosmer-Lemeshow test. IMPROVE Bleed model had AUROC and AUPRC of 0.75 and 0.062, with 95% CIs excluding 0.5 and 0.024, respectively. Hosmer-Lemeshow test was not statistically significant.

CONCLUSION

Despite similarities in coagulation between adolescents and adults, risk assessment models for VTE in adults should not be used for critically ill adolescents. The model for bleeding may be useful.

Prophylactic anticoagulation in children receiving home parenteral nutrition

BACKGROUND

Children with intestinal failure (IF) are at risk of loss of vascular access because of catheter-related venous thrombosis. Whether primary prophylactic anticoagulation is effective and safe in preventing catheter-related thrombosis is largely unknown. Our aim was to assess the incidences of catheter-related venous thrombosis and bleeding complications in children with IF receiving home parenteral nutrition (HPN) treated with primary prophylactic anticoagulation.

METHODS

All children, aged 0-18 years, treated with HPN at the Emma Children's Hospital/Amsterdam UMC were followed from January 2007 to July 2019. All patients were offered primary prophylactic anticoagulation from the start of HPN. The primary outcomes were catheter-related venous thrombosis and bleeding on prophylactic anticoagulation.

RESULTS

In total, 55 (76%) of 74 patients received primary prophylactic anticoagulation. The median age at the start of prophylaxis was 8.4 (interquartile range [IQR], 5.0-55.7) months. Patients were followed for a median of 31.2 (IQR, 10.7-53.5) months, with a total of 65,463 catheter days. The incidence of catheter-related thrombosis on prophylactic anticoagulation was 0.2 per 1000 catheter days. In total, the incidence of clinically relevant bleeding was 0.1 per 1000 catheter days. The median time to first event was 1268 (IQR, 149-2014) days for thrombosis and 389 (IQR, 227-2912) days for clinically relevant bleeding. Cumulative event-free survival after 5 years was 78% for thrombosis.

CONCLUSIONS

Our study shows a low rate of catheter-related venous thrombosis and a slightly elevated rate of clinically relevant bleeding in children receiving HPN and primary prophylactic anticoagulation.

The Incidence and Characteristics of Venous Thromboembolisms in Paediatric-Onset Inflammatory Bowel Disease: A Prospective International Cohort Study Based on the PIBD-SETQuality Safety Registry

BACKGROUND AND AIMS

Guidelines regarding thromboprophylaxis for venous thromboembolisms [VTEs] in children with inflammatory bowel disease [IBD] are based on limited paediatric evidence. We aimed to prospectively assess the incidence of VTEs in paediatric-onset IBD [PIBD], characterize PIBD patients with a VTE and identify potential IBD-related risk factors.

METHODS

From October 2016 to September 2020, paediatric gastroenterologists prospectively replied to the international Safety Registry, monthly indicating whether they had observed a VTE case in a patient <19 years with IBD. IBD details [type, Paris classification, clinical and biochemical disease activity, treatment] and VTE details [type, location, treatment, outcome] were collected. To estimate VTE incidence, participants annually reported the number of PIBD patients, data source and catchment area of their centre. A systematic literature review and meta-analysis was performed to calculate the VTE incidence in the general paediatric population.

RESULTS

Participation of 129 PIBD centres resulted in coverage of 24 802 PIBD patients. Twenty cases of VTE were identified [30% Crohn's disease]. The incidence of VTEs was 3.72 (95% confidence interval [CI] 2.27-5.74) per 10 000 person-years, 14-fold higher than in the general paediatric population (0.27 [95% CI 0.18-0.38], p < 0.001). Cerebral sinus venous thrombosis was most frequently reported [50%]. All but one patient had active IBD, 45% were using steroids and 45% were hospitalized. No patient received thromboprophylaxis, whereas according to current PIBD guidelines, this was recommended in 4/20 patients.

CONCLUSION

There is an increased risk of VTEs in the PIBD population compared to the general paediatric population. Awareness of VTE occurrence and prevention should be extended to all PIBD patients with active disease, especially those hospitalized.

Neonatal thrombosis: risk factors and principles of prophylaxis

Data analysis on the pathogenesis and risk factors of neonatal thrombosis was carried out. The main risk factor of any neonatal thrombosis is central catheter installment, but other maternal, fetal and neonatal factors should be taken into consideration. We discuss the epidemiology of neonatal thrombosis and the main features of the hemostasis system in newborns, the most significant risk factors, including genetic and acquired thrombophilia. We consider the von Willebrand factor activity and ADAMTS-13 (a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13) level in the development of neonatal thrombotic microangiopathy. Finally, we discuss the basic principles of prevented neonatal thrombosis by using low molecular weight heparins.

Efficacy of Early Prophylaxis Against Catheter-Associated Thrombosis in Critically Ill Children: A Bayesian Phase 2b Randomized Clinical Trial

OBJECTIVES

We obtained preliminary evidence on the efficacy of early prophylaxis on the risk of central venous catheter-associated deep venous thrombosis and its effect on thrombin generation in critically ill children.

DESIGN

Bayesian phase 2b randomized clinical trial.

SETTING

Seven PICUs.

PATIENTS

Children less than 18 years old with a newly inserted central venous catheter and at low risk of bleeding.

INTERVENTION

Enoxaparin adjusted to anti-Xa level of 0.2-0.5 international units/mL started at less than 24 hours after insertion of central venous catheter (enoxaparin arm) versus usual care without placebo (usual care arm).

MEASUREMENTS AND MAIN RESULTS

At the interim analysis, the proportion of central venous catheter-associated deep venous thrombosis on ultrasonography in the usual care arm, which was 54.2% of 24 children, was significantly higher than that previously reported. This resulted in misspecification of the preapproved Bayesian analysis, reversal of direction of treatment effect, and early termination of the randomized clinical trial. Nevertheless, with 30.4% of 23 children with central venous catheter-associated deep venous thrombosis on ultrasonography in the enoxaparin arm, risk ratio of central venous catheter-associated deep venous thrombosis was 0.55 (95% credible interval, 0.24-1.11). Including children without ultrasonography, clinically relevant central venous catheter-associated deep venous thrombosis developed in one of 27 children (3.7%) in the enoxaparin arm and seven of 24 (29.2%) in the usual care arm (p = 0.02). Clinically relevant bleeding developed in one child randomized to the enoxaparin arm. Response profile of endogenous thrombin potential, a measure of thrombin generation, was not statistically different between trial arms.

CONCLUSIONS

These findings suggest the efficacy and safety of early prophylaxis that should be validated in a pivotal randomized clinical trial.

Risk Factors of Thrombotic Complications and Antithrombotic Therapy in Paediatric Cardiosurgical Patients

The development of cardiosurgical care for paediatric and neonatal patients is undergoing the rapid growth. Complex, multi-stage reconstructive operations and the use of invasive monitoring are associated with high risk of venous and arterial thrombosis.

The cardiac surgery patient is inherently unique, since it requires controlled anticoagulation during cardiopulmonary bypass. Moreover, the most cardiovascular pediatric patients require antithrombotic measures over the perioperative period. In addition to medication support with the use of various groups of antithrombotic agents, vascular access management is justified in order to minimize the risk of thromboembolic complications, which can affect both the functional status, and common and inter-stage mortality.

The purpose of this review was to systematize the available data on risk factors contributing to the development of thrombotic complications in patients with congenital heart disease.

An information search was carried out using Internet resources (PubMed, Web of Science, eLibrary.ru); literature sources for period 2015–2020 were analysed. As a result of the analysis of the literature data age-dependent features of the haemostatic system, and associated with the defect pathophysiology, and undergone reconstructive interventions were described. The issues of pathophysiology of univentricular heart defects and risk factors associated with thrombosis were also covered.

Moreover, aspects of intraoperative anti-thrombotic support are discussed, as well as measures to prevent thromboembolic complications in this population.

Coordinated actions of haematologists, cardiologists, anaesthesiologists, intensivists, and cardiac surgeons will allow achieving a fine balance between risks of bleeding and thrombosis in the population of paediatric patients undergoing cardiovascular surgery. 

Effectiveness and Safety of Nadroparin Therapy in Preterm and Term Neonates with Venous Thromboembolism

INTRODUCTION

Optimal neonatal nadroparin dosages to treat venous thromboembolism (VTE) are unknown.

OBJECTIVE

To evaluate therapeutic nadroparin dosages to reach therapeutic target ranges (TTR: 0.5-1.0 International Unit (IU)/mL) and the effectiveness and safety of nadroparin in neonatal VTE.

METHODS

Retrospective study including neonates with VTE on nadroparin in a tertiary center between 2007 and 2018. Two groups were distinguished: neonates before (group 1) and after (group 2) switch to higher starting dosages in 2014.

RESULTS

Sixty-one neonates (44 preterm, 17 term) with 64 VTEs were included. TTR was reached in 32/64 (50%) VTEs (group 1: 35.7%; group 2: 61.1%). Median nadroparin dosage to reach TTR was 197 (97.9-330.3) IU/kg/12 h. No therapy-related deaths occurred. Recurrent VTE developed in 6 (9.8%) neonates. Complete clot resolution was observed in 31/41 (75.6%) VTEs. TTR was reached in 58.1% VTEs with complete clot resolution. No major bleeding occurred. Non-major clinically relevant bleedings occurred in 3/64 (4.7%) VTEs, consisting of large hematomas due to the use of subcutaneous catheters.

CONCLUSIONS

High nadroparin dosages are needed to reach TTR in neonates, which seem to be safe. Clot resolution may occur without reaching TTR. Subcutaneous catheters may cause important bleeding complications.

Dabigatran etexilate for the treatment of acute venous thromboembolism in children (DIVERSITY): a randomised, controlled, open-label, phase 2b/3, non-inferiority trial

BACKGROUND

Dabigatran etexilate is a direct oral anticoagulant with potential to overcome the limitations of standard of care in children with venous thromboembolism. The aims of this clinical trial were to study the appropriateness of a paediatric dabigatran dosing algorithm, and the efficacy and safety of dabigatran dosed according to that algorithm versus standard of care in treating children with venous thromboembolism.

METHODS

DIVERSITY is a randomised, controlled, open-label, parallel-group, phase 2b/3 non-inferiority trial done in 65 centres in 26 countries. Standard of care (low-molecular-weight heparins, unfractionated heparin, vitamin K antagonists or fondaparinux) was compared with a paediatric oral dabigatran dosing regimen (an age-adjusted and weight-adjusted nomogram) in children younger than 18 years with acute venous thromboembolism initially treated (5-21 days) with parenteral anticoagulation, requiring anticoagulation therapy for at least 3 months. Patients were randomised 1:2 (standard of care:dabigatran) and stratified by age (12 to <18 years, 2 to <12 years, and birth to <2 years) via interactive response technology. The primary composite efficacy endpoint (intention-to-treat analysis) was the proportion of children with complete thrombus resolution, and freedom from recurrent venous thromboembolism and venous thromboembolism-related death. A non-inferiority margin of absolute differences of 20% was used. Secondary endpoints included safety (determined by major bleeding events [time-to-event analysis on the treated set]), and pharmacokinetic-pharmacodynamic relationships (descriptive analyses). This trial is registered with ClinicalTrials.gov, NCT01895777 and is completed.

FINDINGS

328 children were enrolled between Feb 18, 2014, and Nov 14, 2019. 267 were randomly assigned (90 [34%] to standard of care and 177 [66%] to dabigatran) and included in the analyses. Median exposure to standard of care was 85·0 days (IQR 80·0-90·0) and to dabigatran was 84·5 days (78·0-89·0). Similar proportions of children treated with standard of care and dabigatran met the composite efficacy endpoint (38 [42%] of 90 vs 81 [46%] of 177; Mantel-Haenszel weighted difference, -0·04; 90% CI -0·14 to 0·07; p<0·0001 for non-inferiority). On-treatment bleeding events were reported in 22 (24%) of 90 children receiving standard of care and 38 (22%) of 176 children receiving dabigatran (hazard ratio [HR] 1·15, 95% CI 0·68 to 1·94; p=0·61); major bleeding events were similar between the groups (two [2%] of 90 and four [2%] of 176; HR 0·94, 95% CI 0·17 to 5·16; p=0·95). Pharmacokinetic-pharmacodynamic curves showed a linear relationship between total dabigatran plasma concentration and diluted thrombin time and ecarin clotting time, and a non-linear relationship with activated partial thromboplastin time; curves were similar to those for adults. Serious adverse events were reported for 18 (20%) of 90 children receiving standard of care and 22 (13%) of 176 children receiving dabigatran. The most common severe adverse events were vascular disorders (standard of care three [3%] of 90, dabigatran two [1%] of 176), and gastrointestinal disorders (standard of care two [2%] of 90 and dabigatran five [3%] of 176). One on-treatment death occurred in the standard of care group (retroperitoneal bleeding, not considered treatment related by the study investigators).

INTERPRETATION

An age-adjusted and weight-adjusted dabigatran dosing algorithm was appropriate in children aged birth to less than 18 years with venous thromboembolism. Dabigatran was non-inferior to standard of care in terms of efficacy, with similar pharmacokinetic-pharmacodynamic relationships as those seen in adults, and might be a suitable alternative to standard of care.

FUNDING

Boehringer Ingelheim.

FondaKIDS III: A long-term retrospective cohort study of fondaparinux for treatment of venous thromboembolism in children

BACKGROUND

The incidence of venous thromboembolism (VTE) and use of anticoagulation are rising in children, but treatment options remain limited. As a newer anticoagulant, fondaparinux may be a safe and effective alternative with the benefit of once-daily dosing, but there is relatively little data supporting its use.

PROCEDURE

This retrospective cohort study describes the long-term dosing, efficacy, and safety of fondaparinux for treatment of VTE in children at a single institution. The study included children <18 years old treated with fondaparinux for VTE between 2008 and 2018. Descriptive statistics were used to present the findings.

RESULTS

A total of 277 patients were identified and analyzed in this study. Seventy-six percent of patients reached therapeutic levels with 0 or 1 dose adjustments over a median treatment duration of 93 days. Of the patients included in the efficacy analysis, 91% of patients had improvement in their clot status, including 69% (160/233) with complete resolution and 22% (53/233) with partial resolution. Twenty-six patients (11%) had VTE recurrence, but only seven (3%) of the new thrombi developed while on fondaparinux. Major bleeding occurred in seven patients (2.5%), primarily in patients with underlying medical conditions with increased bleeding risk. Minor bleeding occurred in 53 patients (19%).

CONCLUSIONS

This study demonstrates the stable long-term pediatric dosing of fondaparinux with similar efficacy and safety when compared to other anticoagulants. Given its advantages, fondaparinux can be considered a reasonable alternative for treatment of VTE in children.

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.